Refactor feedkit boundaries ahead of v1

Remove global Postgres schema registration in favor of explicit schema-aware sink factory wiring, and update weatherfeeder to register the Postgres sink explicitly. Add optional per-source HTTP timeout and response body limit overrides while keeping feedkit defaults. Remove remaining legacy source/config compatibility surfaces, including singular kind support and old source registry/type aliases, and migrate weatherfeeder sources to plural `Kinds()` metadata. Clean up related docs, tests, and sample config to match the new Postgres, HTTP, and NATS configuration model.

README.md

@@ -1,255 +1,92 @@
 # feedkit
 
-**feedkit** provides the domain-agnostic core plumbing for *feed-processing daemons*.
+`feedkit` is a small Go toolkit for building feed-processing daemons.
 
-A feed daemon is a long-running process that:
-- polls one or more upstream providers (HTTP APIs, RSS feeds, etc.)
-- normalizes upstream data into a consistent internal representation
-- applies lightweight policy (dedupe, rate-limit, filtering)
-- emits events to one or more sinks (stdout, files, databases, brokers)
+It gives you the reusable plumbing around collection, processing, routing, and
+emission, while leaving domain concepts, schemas, and application wiring in
+your daemon. The intended shape is a family of sibling applications such as
+`weatherfeeder`, `newsfeeder`, or `earthquakefeeder` that all share the same
+infrastructure patterns without sharing domain logic.
 
-feedkit is designed to be reused by many concrete daemons (e.g. `weatherfeeder`,
-`newsfeeder`, `rssfeeder`) without embedding *any* domain-specific logic.
+## What It Does
 
----
+A daemon built on `feedkit` typically:
+- ingests upstream input by polling HTTP APIs or consuming streams
+- emits domain-agnostic `event.Event` values
+- optionally processes those events with stages like dedupe or normalization
+- routes events to one or more sinks such as stdout, NATS, or Postgres
+
+Conceptually, the pipeline is:
+
+`Collect -> Process -> Route -> Emit`
 
 ## Philosophy
 
-feedkit is **not a framework**.
+`feedkit` is intentionally not a framework.
 
-It does **not**:
-- define domain schemas
-- enforce allowed event kinds
-- hide control flow behind inversion-of-control magic
-- own your application lifecycle
+It does not try to own:
+- your domain payload schemas
+- your domain event kinds
+- your daemon lifecycle or `main.go`
+- your observability stack or deployment model
 
-Instead, it provides **small, composable primitives** that concrete daemons wire
-together explicitly. The goal is clarity, predictability, and long-term
-maintainability.
+Instead, it provides small composable packages that are easy to wire together in
+different daemons.
 
----
+## When To Use It
 
-## Conceptual pipeline
+`feedkit` is a good fit when you want:
+- multiple small ingestion daemons with shared infrastructure patterns
+- clear separation between raw upstream payloads and normalized canonical models
+- reusable routing and sink behavior across domains
+- strong config and event-envelope conventions without centralizing domain rules
 
-Collect → Normalize → Filter / Policy → Route → Persist / Emit
+It is a poor fit if you want a monolithic framework that dictates application
+structure end-to-end.
 
-In feedkit terms:
+## Built-In Capabilities
 
-| Stage      | Package(s)                           |
-|------------|--------------------------------------|
-| Collect    | `sources`, `scheduler`               |
-| Normalize  | *(today: domain code; planned: pipeline processor)* |
-| Policy     | `pipeline`                           |
-| Route      | `dispatch`                           |
-| Emit       | `sinks`                              |
-| Configure  | `config`                             |
+`feedkit` currently includes:
+- strict YAML config loading and validation
+- polling and streaming source abstractions
+- scheduler orchestration for configured sources
+- optional pipeline processors
+- built-in dedupe and normalization processors
+- route compilation and sink fanout
+- built-in sinks for `stdout`, `nats`, and `postgres`
 
----
+The Postgres sink is intentionally split between feedkit-owned infrastructure
+and daemon-owned schema mapping. `feedkit` manages connection setup, DDL,
+writes, and pruning; downstream applications define the schema and event mapper.
 
-## Public API overview
+## Typical Wiring
 
-### `config` — Configuration loading & validation  
-**Status:** 🟢 Stable
+At a high level, a daemon built on `feedkit` does this:
 
-- Loads YAML configuration
-- Strict decoding (`KnownFields(true)`)
-- Domain-agnostic validation only (shape, required fields, references)
-- Flexible `Params map[string]any` with typed helpers
+1. Load config.
+2. Register domain-specific source drivers.
+3. Register built-in and/or custom sinks.
+4. Build sources, sinks, and optional processor chain from config.
+5. Compile routes.
+6. Start the scheduler and dispatcher.
 
-Key types:
-- `config.Config`
-- `config.SourceConfig`
-- `config.SinkConfig`
-- `config.Load(path)`
+The package docs are the better source of truth for code-level details. In
+particular, each subpackage `doc.go` describes its external API surface and any
+optional helper APIs in `helpers.go`.
 
----
+## Package Layout
 
-### `event` — Domain-agnostic event envelope  
-**Status:** 🟢 Stable
+The major packages are:
+- `config`: config loading and validation
+- `event`: the domain-agnostic event envelope
+- `sources`: source interfaces and reusable source helpers
+- `scheduler`: source execution and cadence management
+- `processors`: processor interfaces and registry
+- `processors/dedupe`: built-in in-memory dedupe processor
+- `processors/normalize`: built-in normalization processor and helpers
+- `pipeline`: optional processor chain
+- `dispatch`: route compilation and fanout
+- `sinks`: sink interfaces, built-ins, and explicit Postgres factory helpers
 
-Defines the canonical event structure that moves through feedkit.
-
-Includes:
-- Stable ID
-- Kind (stringly-typed, domain-defined)
-- Source name
-- Timestamps (`EmittedAt`, optional `EffectiveAt`)
-- Optional `Schema` for payload versioning
-- Opaque `Payload`
-
-Key types:
-- `event.Event`
-- `event.Kind`
-- `event.ParseKind`
-- `event.Event.Validate`
-
-feedkit infrastructure never inspects `Payload`.
-
----
-
-### `sources` — Polling abstraction  
-**Status:** 🟢 Stable (interface); 🔵 evolving patterns
-
-Defines the contract implemented by domain-specific polling jobs.
-
-```go
-type Source interface {
-    Name() string
-    Kind() event.Kind
-    Poll(ctx context.Context) ([]event.Event, error)
-}
-```
-Includes a registry (sources.Registry) so daemons can register drivers
-(e.g. openweather_observation, rss_feed) without switch statements.
-
-Note: Today, most sources both fetch and normalize. A dedicated
-normalization hook is planned (see below).
-
-### `scheduler` — Time-based polling
-
-**Status:** 🟢 Stable
-
-Runs one goroutine per source on a configured interval with jitter.
-
-Features:
-- Per-source interval
-- Deterministic jitter (avoids thundering herd)
-- Immediate poll at startup
-- Context-aware shutdown
-
-Key types:
-- `scheduler.Scheduler`
-- `scheduler.Job`
-
-### `pipeline` — Event processing chain
-**Status:** 🟡 Partial (API stable, processors evolving)
-
-Allows events to be transformed, dropped, or rejected between collection
-and dispatch.
-
-```go
-type Processor interface {
-    Process(ctx context.Context, in event.Event) (*event.Event, error)
-}
-```
-
-Current state:
-- `pipeline.Pipeline` is fully implemented
-
-Placeholder files exist for:
-- `dedupe` (planned)
-- `ratelimit` (planned)
-
-This is the intended home for:
-- normalization
-- deduplication
-- rate limiting
-- lightweight policy enforcement
-
-### `dispatch` — Routing & fan-out
-**Status:** 🟢 Stable
-
-Routes events to sinks based on kind and isolates slow sinks.
-
-Features:
-- Compiled routing rules
-- Per-sink buffered queues
-- Bounded enqueue timeouts
-- Per-consume timeouts
-- Sink panic isolation
-- Context-aware shutdown
-
-Key types:
-- `dispatch.Dispatcher`
-- `dispatch.Route`
-- `dispatch.Fanout`
-
-### `sinks` — Output adapters
-***Status:*** 🟡 Mixed
-
-Defines where events go after processing.
-
-```go
-type Sink interface {
-    Name() string
-    Consume(ctx context.Context, e event.Event) error
-}
-```
-
-Registry-based construction allows daemons to opt into any sink drivers.
-
-Sink	Status
-stdout	🟢 Implemented
-file	🔴 Stub
-postgres	🔴 Stub
-rabbitmq	🔴 Stub
-
-All sinks are required to respect context cancellation.
-
-### Normalization (planned)
-**Status:** 🔵 Planned (API design in progress)
-
-Currently, most domain implementations normalize upstream data inside
-`sources.Source.Poll`, which leads to:
-- very large source files
-- mixed responsibilities (HTTP + mapping)
-- duplicated helper code
-
-The intended evolution is:
-- Sources emit raw events (e.g. `json.RawMessage`)
-- A dedicated normalization processor runs in the pipeline
-- Normalizers are selected by `Event.Schema`, `Kind`, or `Source`
-
-This keeps:
-- `feedkit` domain-agnostic
-- `sources` small and focused
-- normalization logic centralized and testable
-
-### Runner helper (planned)
-**Status:** 🔵 Planned (optional convenience)
-
-Most daemons wire together the same steps:
-- load config
-- build sources
-- build sinks
-- compile routes
-- start scheduler
-- start dispatcher
-
-A small, opt-in `Runner` helper may be added to reduce boilerplate while keeping the system explicit and debuggable.
-
-This is not intended to become a framework.
-
-## Stability summary
-Area	Status
-Event model	🟢 Stable
-Config API	🟢 Stable
-Scheduler	🟢 Stable
-Dispatcher	🟢 Stable
-Source interface	🟢 Stable
-Pipeline core	🟡 Partial
-Normalization	🔵 Planned
-Dedupe/Ratelimit	🔵 Planned
-Non-stdout sinks	🔴 Stub
-
-Legend:
-🟢 Stable — API considered solid
-🟡 Partial — usable, but incomplete
-🔵 Planned — design direction agreed, not yet implemented
-🔴 Stub — placeholder only
-
-## Non-goals
-`feedkit` intentionally does not:
-- define domain payload schemas
-- enforce domain-specific validation
-- manage persistence semantics beyond sink adapters
-- own observability, metrics, or tracing (left to daemons)
-
-Those concerns belong in concrete implementations.
-
-## See also
-- NAMING.md — repository and daemon naming conventions
-- event/doc.go — detailed event semantics
-- **Concrete example:** weatherfeeder (reference implementation)
-
----
+The root package docs in `doc.go` provide a concise package-by-package map for
+Go documentation consumers.

config/config.go

@@ -21,31 +21,79 @@ type Config struct {
 	Routes  []RouteConfig  `yaml:"routes"`
 }
 
-// SourceConfig describes one polling job.
+// SourceMode selects how a source receives upstream input.
+//
+// Empty mode means "auto": feedkit infers mode from the registered driver type.
+type SourceMode string
+
+const (
+	SourceModeAuto   SourceMode = ""
+	SourceModePoll   SourceMode = "poll"
+	SourceModeStream SourceMode = "stream"
+)
+
+// Normalize lowercases and trims the mode.
+func (m SourceMode) Normalize() SourceMode {
+	switch strings.ToLower(strings.TrimSpace(string(m))) {
+	case "":
+		return SourceModeAuto
+	case string(SourceModePoll):
+		return SourceModePoll
+	case string(SourceModeStream):
+		return SourceModeStream
+	default:
+		return SourceMode(strings.ToLower(strings.TrimSpace(string(m))))
+	}
+}
+
+// SourceConfig describes one input source.
 //
 // This is intentionally generic:
 //   - driver-specific knobs belong in Params.
-//   - "kind" is allowed (useful for safety checks / routing), but feedkit does not
-//     restrict the allowed values.
+//   - mode controls polling vs streaming behavior.
+//   - expected emitted kinds are optional and domain-defined.
 type SourceConfig struct {
 	Name   string `yaml:"name"`
 	Driver string `yaml:"driver"` // e.g. "openmeteo_observation", "rss_feed", etc.
 
-	Every Duration `yaml:"every"` // "15m", "1m", etc.
+	// Mode is optional:
+	//   - "poll": Every must be set (>0)
+	//   - "stream": Every must be omitted/zero
+	//   - empty: infer from driver registration type (poll vs stream)
+	Mode SourceMode `yaml:"mode"`
 
-	// Kind is optional and domain-defined. If set, it should be a non-empty string.
-	// Domains commonly use it to enforce "this source should only emit kind X".
-	Kind string `yaml:"kind"`
+	// Every is the poll cadence for poll-mode sources ("15m", "1m", etc.).
+	Every Duration `yaml:"every"`
+
+	// Kinds is optional and domain-defined.
+	// If set, it describes the expected emitted event kinds for this source.
+	Kinds []string `yaml:"kinds"`
 
 	// Params are driver-specific settings (URL, headers, station IDs, API keys, etc.).
 	// The driver implementation is responsible for reading/validating these.
 	Params map[string]any `yaml:"params"`
 }
 
+// ExpectedKinds returns normalized expected kinds from config.
+func (cfg SourceConfig) ExpectedKinds() []string {
+	out := make([]string, 0, len(cfg.Kinds))
+	for _, k := range cfg.Kinds {
+		k = strings.TrimSpace(k)
+		if k == "" {
+			continue
+		}
+		out = append(out, k)
+	}
+	if len(out) == 0 {
+		return nil
+	}
+	return out
+}
+
 // SinkConfig describes one output sink adapter.
 type SinkConfig struct {
 	Name   string         `yaml:"name"`
-	Driver string         `yaml:"driver"` // "stdout", "file", "postgres", "rabbitmq", ...
+	Driver string         `yaml:"driver"` // "stdout", "nats", "postgres", ...
 	Params map[string]any `yaml:"params"` // sink-specific settings
 }
 

config/config_test.go

@@ -0,0 +1,48 @@
+package config
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestSourceConfigExpectedKinds(t *testing.T) {
+	tests := []struct {
+		name string
+		cfg  SourceConfig
+		want []string
+	}{
+		{
+			name: "plural kinds normalized",
+			cfg: SourceConfig{
+				Kinds: []string{" observation ", "forecast"},
+			},
+			want: []string{"observation", "forecast"},
+		},
+		{
+			name: "empty kinds",
+			cfg:  SourceConfig{},
+			want: nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := tt.cfg.ExpectedKinds()
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Fatalf("ExpectedKinds() = %#v, want %#v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestSourceModeNormalize(t *testing.T) {
+	if got := SourceMode(" Poll ").Normalize(); got != SourceModePoll {
+		t.Fatalf("Normalize poll = %q, want %q", got, SourceModePoll)
+	}
+	if got := SourceMode("STREAM").Normalize(); got != SourceModeStream {
+		t.Fatalf("Normalize stream = %q, want %q", got, SourceModeStream)
+	}
+	if got := SourceMode("").Normalize(); got != SourceModeAuto {
+		t.Fatalf("Normalize auto = %q, want %q", got, SourceModeAuto)
+	}
+}

config/load.go

@@ -83,14 +83,34 @@ func (c *Config) Validate() error {
 				m.Add(fieldErr(path+".driver", "is required (e.g. openmeteo_observation, rss_feed, ...)"))
 			}
 
-			// Every
-			if s.Every.Duration <= 0 {
-				m.Add(fieldErr(path+".every", "must be a positive duration (e.g. 15m, 1m, 30s)"))
+			// Mode
+			mode := s.Mode.Normalize()
+			if s.Mode != SourceModeAuto && mode != SourceModePoll && mode != SourceModeStream {
+				m.Add(fieldErr(path+".mode", `must be one of: "poll", "stream" (or omit for auto)`))
 			}
 
-			// Kind (optional but if present must be non-empty after trimming)
-			if s.Kind != "" && strings.TrimSpace(s.Kind) == "" {
-				m.Add(fieldErr(path+".kind", "cannot be blank (omit it entirely, or provide a non-empty string)"))
+			// Every
+			if s.Every.Duration < 0 {
+				m.Add(fieldErr(path+".every", "is optional, but must be a positive duration (e.g. 15m, 1m, 30s) if provided"))
+			} else {
+				switch mode {
+				case SourceModePoll:
+					if s.Every.Duration <= 0 {
+						m.Add(fieldErr(path+".every", `is required when mode="poll" (e.g. 15m, 1m, 30s)`))
+					}
+				case SourceModeStream:
+					if s.Every.Duration > 0 {
+						m.Add(fieldErr(path+".every", `must be omitted when mode="stream"`))
+					}
+				}
+			}
+
+			// Kinds (optional)
+			for j, k := range s.Kinds {
+				kpath := fmt.Sprintf("%s.kinds[%d]", path, j)
+				if strings.TrimSpace(k) == "" {
+					m.Add(fieldErr(kpath, "kind cannot be empty"))
+				}
 			}
 
 			// Params can be nil; that's fine.
@@ -115,7 +135,7 @@ func (c *Config) Validate() error {
 			}
 
 			if strings.TrimSpace(s.Driver) == "" {
-				m.Add(fieldErr(path+".driver", "is required (stdout|file|postgres|rabbitmq|...)"))
+				m.Add(fieldErr(path+".driver", "is required (stdout|nats|postgres|...)"))
 			}
 
 			// Params can be nil; that's fine.

config/validate_test.go

@@ -46,3 +46,94 @@ func TestValidate_RouteKindsRejectsBlankEntries(t *testing.T) {
 		t.Fatalf("expected error to mention blank kind entry, got: %v", err)
 	}
 }
+
+func TestValidate_SourceModePollRequiresEvery(t *testing.T) {
+	cfg := &Config{
+		Sources: []SourceConfig{
+			{Name: "src1", Driver: "driver1", Mode: SourceModePoll},
+		},
+		Sinks: []SinkConfig{
+			{Name: "sink1", Driver: "stdout"},
+		},
+	}
+
+	err := cfg.Validate()
+	if err == nil {
+		t.Fatalf("expected error, got nil")
+	}
+	if !strings.Contains(err.Error(), `sources[0].every`) {
+		t.Fatalf("expected error to mention sources[0].every, got: %v", err)
+	}
+}
+
+func TestValidate_SourceModeStreamRejectsEvery(t *testing.T) {
+	cfg := &Config{
+		Sources: []SourceConfig{
+			{
+				Name:   "src1",
+				Driver: "driver1",
+				Mode:   SourceModeStream,
+				Every:  Duration{Duration: time.Minute},
+			},
+		},
+		Sinks: []SinkConfig{
+			{Name: "sink1", Driver: "stdout"},
+		},
+	}
+
+	err := cfg.Validate()
+	if err == nil {
+		t.Fatalf("expected error, got nil")
+	}
+	if !strings.Contains(err.Error(), `sources[0].every`) {
+		t.Fatalf("expected error to mention sources[0].every, got: %v", err)
+	}
+}
+
+func TestValidate_SourceModeRejectsUnknownValue(t *testing.T) {
+	cfg := &Config{
+		Sources: []SourceConfig{
+			{
+				Name:   "src1",
+				Driver: "driver1",
+				Mode:   SourceMode("batch"),
+				Every:  Duration{Duration: time.Minute},
+			},
+		},
+		Sinks: []SinkConfig{
+			{Name: "sink1", Driver: "stdout"},
+		},
+	}
+
+	err := cfg.Validate()
+	if err == nil {
+		t.Fatalf("expected error, got nil")
+	}
+	if !strings.Contains(err.Error(), `sources[0].mode`) {
+		t.Fatalf("expected error to mention sources[0].mode, got: %v", err)
+	}
+}
+
+func TestValidate_SourceKindsRejectBlankEntries(t *testing.T) {
+	cfg := &Config{
+		Sources: []SourceConfig{
+			{
+				Name:   "src1",
+				Driver: "driver1",
+				Every:  Duration{Duration: time.Minute},
+				Kinds:  []string{"observation", "   "},
+			},
+		},
+		Sinks: []SinkConfig{
+			{Name: "sink1", Driver: "stdout"},
+		},
+	}
+
+	err := cfg.Validate()
+	if err == nil {
+		t.Fatalf("expected error, got nil")
+	}
+	if !strings.Contains(err.Error(), `sources[0].kinds[1]`) {
+		t.Fatalf("expected error to mention sources[0].kinds[1], got: %v", err)
+	}
+}

doc.go

@@ -1,334 +1,56 @@
-// Package feedkit provides domain-agnostic plumbing for "feed processing daemons".
+// Package feedkit provides a high-level map of the feedkit package set.
 //
-// A feed daemon polls one or more upstream providers (HTTP APIs, RSS, etc.),
-// converts upstream items into a normalized internal representation, applies
-// lightweight policy (dedupe/rate-limit/filters), and emits events to one or
-// more sinks (stdout, files, Postgres, brokers, ...).
+// Most real applications do not import the root package directly. Instead, they
+// compose the subpackages that handle configuration, collection, processing,
+// routing, and sinks.
 //
-// feedkit is intentionally NOT a framework. It supplies small, composable
-// primitives that concrete daemons wire together in main.go (or via a small
-// optional Runner helper, see "Future additions").
+// The usual flow through feedkit is:
 //
-// Conceptual pipeline
+//	Collect -> Process -> Route -> Emit
 //
-//	Collect → Normalize → Filter/Policy → Persist/Emit → Signal
-//
-// In feedkit today, that maps to:
-//
-//	Collect:     sources.Source + scheduler.Scheduler
-//	Normalize:   (optional) normalize.Processor (or domain code inside Source.Poll)
-//	Policy:      pipeline.Pipeline (Processor chain; dedupe/ratelimit are planned)
-//	Emit:        dispatch.Dispatcher + dispatch.Fanout
-//	Sinks:       sinks.Sink (+ sinks.Registry to build from config)
-//	Config:      config.Load + config.Config validation
-//
-// Public packages (API surface)
+// That flow maps to packages like this:
 //
 //   - config
-//     YAML configuration types and loader/validator.
-//
-//   - config.Load(path) (*config.Config, error)
-//
-//   - config.Config: Sources, Sinks, Routes
-//
-//   - config.SourceConfig / SinkConfig include Params map[string]any
-//     with convenience helpers like:
-//
-//   - ParamString / ParamStringDefault
-//
-//   - ParamBool / ParamBoolDefault
-//
-//   - ParamInt / ParamIntDefault
-//
-//   - ParamDuration / ParamDurationDefault
-//
-//   - ParamStringSlice
+//     Loads and validates daemon config. This package owns domain-agnostic
+//     config shape and consistency checks.
 //
 //   - event
-//     Domain-agnostic event envelope moved through the system.
-//
-//   - event.Event includes ID, Kind, Source, timestamps, Schema, Payload
-//
-//   - event.Kind is stringly typed; event.ParseKind normalizes/validates.
+//     Defines the event.Event envelope shared across sources, processors,
+//     dispatch, and sinks.
 //
 //   - sources
-//     Extension point for domain-specific polling jobs.
-//
-//   - sources.Source interface: Name(), Kind(), Poll(ctx)
-//
-//   - sources.Registry lets daemons register driver factories and build
-//     sources from config.SourceConfig.
+//     Defines polling and streaming source interfaces, the source registry, and
+//     reusable source helpers.
 //
 //   - scheduler
-//     Runs sources on a cadence and publishes emitted events onto a channel.
+//     Runs configured sources on a cadence or as long-lived stream workers.
 //
-//   - scheduler.Scheduler{Jobs, Out, Logf}.Run(ctx)
+//   - processors
+//     Defines the generic processor interface and registry used to build
+//     ordered processor chains.
 //
-//   - scheduler.Job: {Source, Every, Jitter}
+//   - processors/dedupe
+//     Built-in in-memory dedupe processor keyed by Event.ID.
+//
+//   - processors/normalize
+//     Built-in normalization processor plus helper APIs for raw-to-canonical
+//     event mapping.
 //
 //   - pipeline
-//     Optional processing chain between scheduler and dispatch.
-//
-//   - pipeline.Pipeline{Processors}.Process(ctx, event)
-//
-//   - pipeline.Processor can mutate, drop (return nil), or error.
-//
-//   - dedupe/ratelimit processors are placeholders (planned).
-//
-//   - normalize
-//     Optional normalization hook for splitting "fetch" from "transform".
-//
-//     Many domains (like weather) ingest multiple upstream providers whose payloads
-//     differ. A common evolution is to keep sources small and focused on polling,
-//     and move mapping/normalization into a dedicated stage.
-//
-//     feedkit provides this as an OPTIONAL pipeline processor:
-//
-//   - normalize.Normalizer: domain-implemented mapping logic
-//
-//   - normalize.Registry: holds normalizers and selects one by Match()
-//
-//   - normalize.Processor: adapts Registry into a pipeline.Processor
-//
-//     Normalization is NOT required:
-//
-//   - If you do all normalization inside Source.Poll, you can ignore this package.
-//
-//   - If normalize.Processor is not installed in your pipeline, nothing changes.
-//
-//   - If normalize.Processor is installed but no Normalizer matches an event,
-//     the event passes through unchanged.
-//
-//     The key types:
-//
-//     type Normalizer interface {
-//     // Match returns true if this normalizer should handle the event.
-//     // Matching is intentionally flexible: match on Schema, Kind, Source,
-//     // or any combination.
-//     Match(e event.Event) bool
-//
-//     // Normalize converts the incoming event into a new (or modified) event.
-//     //
-//     // Return values:
-//     //   - (out, nil) where out != nil: emit the normalized event
-//     //   - (nil, nil): drop the event (policy drop)
-//     //   - (nil, err): fail the pipeline
-//     Normalize(ctx context.Context, in event.Event) (*event.Event, error)
-//     }
-//
-//     type Registry struct { ... }
-//
-//     func (r *Registry) Register(n Normalizer)
-//
-//     // Normalize finds the first matching normalizer (in registration order) and applies it.
-//     // If none match, it returns the input event unchanged.
-//     func (r *Registry) Normalize(ctx context.Context, in event.Event) (*event.Event, error)
-//
-//     // Processor implements pipeline.Processor and calls into the Registry.
-//     // Optional behavior:
-//     //   - If Registry is nil, Processor is a no-op pass-through.
-//     //   - If RequireMatch is false (default), non-matching events pass through.
-//     //   - If RequireMatch is true, non-matching events are treated as errors.
-//     type Processor struct {
-//     Registry     *Registry
-//     RequireMatch bool
-//     }
-//
-//     "First match wins":
-//     Registry applies the first Normalizer whose Match() returns true.
-//     This is intentional: normalization is usually a single mapping step from a
-//     raw schema into a canonical schema. If you want multiple sequential transforms,
-//     model them as multiple pipeline processors.
-//
-//     Recommended convention: match by Event.Schema
-//     ------------------------------------------------
-//     Schema gives you a versionable selector that doesn't depend on source names.
-//
-//     A common pattern is:
-//
-//   - sources emit "raw" events with Schema like:
-//     "raw.openweather.current.v1"
-//     "raw.openmeteo.current.v1"
-//     "raw.nws.observation.v1"
-//
-//   - normalizers transform them into canonical domain schemas like:
-//     "weather.observation.v1"
-//     "weather.forecast.v1"
-//     "weather.alert.v1"
-//
-//     What is a "raw event"?
-//     ------------------------------------------------
-//     feedkit does not prescribe the raw payload representation.
-//     A raw payload is typically one of:
-//
-//   - json.RawMessage (recommended for JSON APIs)
-//
-//   - []byte (raw bytes)
-//
-//   - map[string]any (already-decoded but untyped JSON)
-//
-//     The only hard requirement enforced by feedkit is Event.Validate():
-//
-//   - ID, Kind, Source, EmittedAt must be set
-//
-//   - Payload must be non-nil
-//
-//     If you use raw events, you still must provide Event.Kind.
-//     Typical approaches:
-//
-//   - set Kind to the intended canonical kind (e.g. "observation") even before normalization
-//
-//   - or set Kind to a domain-defined "raw_*" kind and normalize it later
-//
-//     The simplest approach is: set Kind to the final kind early, and use Schema
-//     to describe the raw-vs-normalized payload shape.
-//
-//     Wiring example (daemon main.go)
-//     ------------------------------------------------
-//     Install normalize.Processor at the front of your pipeline:
-//
-//     normReg := &normalize.Registry{}
-//
-//     normReg.Register(normalize.Func{
-//     Name: "openweather current -> weather.observation.v1",
-//     MatchFn: func(e event.Event) bool {
-//     return e.Schema == "raw.openweather.current.v1"
-//     },
-//     NormalizeFn: func(ctx context.Context, in event.Event) (*event.Event, error) {
-//     // 1) interpret in.Payload (json.RawMessage / []byte / map)
-//     // 2) build canonical domain payload
-//     // 3) return updated event
-//
-//     out := in
-//     out.Schema = "weather.observation.v1"
-//     // Optionally adjust Kind, EffectiveAt, etc.
-//     out.Payload = /* canonical weather observation struct */
-//     return &out, nil
-//     },
-//     })
-//
-//     p := &pipeline.Pipeline{
-//     Processors: []pipeline.Processor{
-//     normalize.Processor{Registry: normReg}, // optional stage
-//     // dedupe.New(...), ratelimit.New(...), ...
-//     },
-//     }
-//
-//     If the event does not match any normalizer, it passes through unmodified.
-//
-//   - sinks
-//     Extension point for output adapters.
-//
-//   - sinks.Sink interface: Name(), Consume(ctx, event)
-//
-//   - sinks.Registry to register driver factories and build sinks from config
-//
-//   - sinks.RegisterBuiltins registers feedkit-provided sink drivers
-//     (stdout/file/postgres/rabbitmq; some are currently stubs).
+//     Applies an ordered processor chain between collection and dispatch.
 //
 //   - dispatch
-//     Routes processed events to sinks, and isolates slow sinks via per-sink queues.
+//     Compiles routes and fans events out to sinks with per-sink isolation.
 //
-//   - dispatch.Dispatcher{In, Pipeline, Sinks, Routes, ...}.Run(ctx, logf)
+//   - sinks
+//     Defines sink interfaces, the sink registry, schema-free built-in sinks,
+//     and explicit Postgres factory helpers.
 //
-//   - dispatch.Fanout: one buffered queue + worker goroutine per sink
+// feedkit is intentionally domain-agnostic. Domain schemas, domain event kinds,
+// upstream-specific parsing, and daemon lifecycle remain the responsibility of
+// each concrete application.
 //
-//   - dispatch.CompileRoutes(*config.Config) compiles cfg.Routes into []dispatch.Route.
-//     If routes: is omitted, it defaults to "all sinks receive all kinds". If a route
-//     omits kinds: (or sets it empty), that route matches all kinds.
-//
-//   - logging
-//     Shared logger type used across feedkit packages.
-//
-//   - logging.Logf is a printf-style logger signature.
-//
-// Typical wiring (what a daemon does in main.go)
-//
-//  1. Load config (domain code may add domain-specific validation).
-//  2. Register and build sources from config.Sources using sources.Registry.
-//  3. Register and build sinks from config.Sinks using sinks.Registry.
-//  4. Compile routes (typically via dispatch.CompileRoutes).
-//  5. Create an event bus channel.
-//  6. Start scheduler (sources → bus).
-//  7. Start dispatcher (bus → pipeline → routes → sinks).
-//
-// A sketch:
-//
-//	cfg, _ := config.Load("config.yml")
-//
-//	// Build sources (domain registers its drivers).
-//	srcReg := sources.NewRegistry()
-//	// domain: srcReg.Register("openweather_observation", newOpenWeatherSource)
-//	// ...
-//
-//	var jobs []scheduler.Job
-//	for _, sc := range cfg.Sources {
-//	    src, _ := srcReg.Build(sc)
-//	    jobs = append(jobs, scheduler.Job{Source: src, Every: sc.Every.Duration})
-//	}
-//
-//	// Build sinks (feedkit can register builtins).
-//	sinkReg := sinks.NewRegistry()
-//	sinks.RegisterBuiltins(sinkReg)
-//	builtSinks := map[string]sinks.Sink{}
-//	for _, sk := range cfg.Sinks {
-//	    s, _ := sinkReg.Build(sk)
-//	    builtSinks[sk.Name] = s
-//	}
-//
-//	// Compile routes.
-//	routes, _ := dispatch.CompileRoutes(cfg)
-//
-//	// Event bus.
-//	bus := make(chan event.Event, 256)
-//
-//	// Optional normalization registry + pipeline.
-//	normReg := &normalize.Registry{}
-//	// domain registers normalizers into normReg...
-//
-//	p := &pipeline.Pipeline{
-//	    Processors: []pipeline.Processor{
-//	        normalize.Processor{Registry: normReg}, // optional
-//	        // dedupe/ratelimit/etc...
-//	    },
-//	}
-//
-//	// Scheduler.
-//	s := &scheduler.Scheduler{Jobs: jobs, Out: bus, Logf: logf}
-//
-//	// Dispatcher.
-//	d := &dispatch.Dispatcher{
-//	    In:       bus,
-//	    Pipeline: p,
-//	    Sinks:    builtSinks,
-//	    Routes:   routes,
-//	}
-//
-//	go s.Run(ctx)
-//	return d.Run(ctx, logf)
-//
-// Conventions (recommended, not required)
-//
-//   - Event.ID should be stable for dedupe/storage (often "<provider>:<upstream-id>").
-//   - Event.Kind should be lowercase ("observation", "alert", "article", ...).
-//   - Event.Schema should identify the payload shape/version
-//     (e.g. "weather.observation.v1").
-//
-// # Context and cancellation
-//
-// All blocking or I/O work should honor ctx.Done():
-//   - sources.Source.Poll should pass ctx to HTTP calls, etc.
-//   - sinks.Sink.Consume should honor ctx (Fanout timeouts only help if sinks cooperate).
-//   - normalizers should honor ctx if they do expensive work (rare; usually pure transforms).
-//
-// Future additions (likely)
-//
-//   - A small Runner helper that performs the standard wiring (load config,
-//     build sources/sinks/routes, run scheduler+dispatcher, handle shutdown).
-//
-// # Non-goals
-//
-// feedkit does not define domain payload schemas, does not enforce domain kinds,
-// and does not embed domain-specific validation rules. Those live in each
-// concrete daemon/module (weatherfeeder, newsfeeder, ...).
+// For repository-level overview and usage narrative, see README.md. For
+// code-level details, each subpackage doc.go is the source of truth for that
+// package's public API surface and optional helpers.
 package feedkit

go.mod

@@ -2,4 +2,16 @@ module gitea.maximumdirect.net/ejr/feedkit
 
 go 1.22
 
-require gopkg.in/yaml.v3 v3.0.1
+require (
+	github.com/lib/pq v1.10.9
+	github.com/nats-io/nats.go v1.34.0
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require (
+	github.com/klauspost/compress v1.17.2 // indirect
+	github.com/nats-io/nkeys v0.4.7 // indirect
+	github.com/nats-io/nuid v1.0.1 // indirect
+	golang.org/x/crypto v0.18.0 // indirect
+	golang.org/x/sys v0.16.0 // indirect
+)

go.sum

@@ -1,3 +1,18 @@
+github.com/klauspost/compress v1.17.2 h1:RlWWUY/Dr4fL8qk9YG7DTZ7PDgME2V4csBXA8L/ixi4=
+github.com/klauspost/compress v1.17.2/go.mod h1:ntbaceVETuRiXiv4DpjP66DpAtAGkEQskQzEyD//IeE=
+github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=
+github.com/lib/pq v1.10.9/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
+github.com/nats-io/nats.go v1.34.0 h1:fnxnPCNiwIG5w08rlMcEKTUw4AV/nKyGCOJE8TdhSPk=
+github.com/nats-io/nats.go v1.34.0/go.mod h1:Ubdu4Nh9exXdSz0RVWRFBbRfrbSxOYd26oF0wkWclB8=
+github.com/nats-io/nkeys v0.4.7 h1:RwNJbbIdYCoClSDNY7QVKZlyb/wfT6ugvFCiKy6vDvI=
+github.com/nats-io/nkeys v0.4.7/go.mod h1:kqXRgRDPlGy7nGaEDMuYzmiJCIAAWDK0IMBtDmGD0nc=
+github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
+github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
+golang.org/x/crypto v0.18.0 h1:PGVlW0xEltQnzFZ55hkuX5+KLyrMYhHld1YHO4AKcdc=
+golang.org/x/crypto v0.18.0/go.mod h1:R0j02AL6hcrfOiy9T4ZYp/rcWeMxM3L6QYxlOuEG1mg=
+golang.org/x/sys v0.16.0 h1:xWw16ngr6ZMtmxDyKyIgsE93KNKz5HKmMa3b8ALHidU=
+golang.org/x/sys v0.16.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

normalize/doc.go

@@ -1,17 +0,0 @@
-// Package normalize provides an OPTIONAL normalization hook for feedkit pipelines.
-//
-// Motivation:
-// Many daemons have sources that:
-//  1. fetch raw upstream data (often JSON), and
-//  2. transform it into a domain's normalized payload format.
-//
-// Doing both steps inside Source.Poll works, but tends to make sources large and
-// encourages duplication (unit conversions, common mapping helpers, etc.).
-//
-// This package lets a source emit a "raw" event (e.g., Schema="raw.openweather.current.v1",
-// Payload=json.RawMessage), and then a normalization processor can convert it into a
-// normalized event (e.g., Schema="weather.observation.v1", Payload=WeatherObservation{}).
-//
-// Key property: normalization is optional.
-// If no registered Normalizer matches an event, it passes through unchanged.
-package normalize

normalize/registry.go

@@ -1,140 +0,0 @@
-package normalize
-
-import (
-	"context"
-	"fmt"
-	"sync"
-
-	"gitea.maximumdirect.net/ejr/feedkit/event"
-)
-
-// Registry holds a set of Normalizers and selects one for a given event.
-//
-// Selection rule (simple + predictable):
-//   - iterate in registration order
-//   - the FIRST Normalizer whose Match(e) returns true is used
-//
-// If none match, the event passes through unchanged.
-//
-// Why "first match wins"?
-// Normalization is usually a single mapping step from a raw schema/version into
-// a normalized schema/version. If you want multiple transformation steps,
-// model them as multiple pipeline processors (which feedkit already supports).
-type Registry struct {
-	mu sync.RWMutex
-	ns []Normalizer
-}
-
-// Register adds a normalizer to the registry.
-//
-// Register panics if n is nil; this is a programmer error and should fail fast.
-func (r *Registry) Register(n Normalizer) {
-	if n == nil {
-		panic("normalize.Registry.Register: normalizer cannot be nil")
-	}
-	r.mu.Lock()
-	defer r.mu.Unlock()
-	r.ns = append(r.ns, n)
-}
-
-// Normalize finds the first matching Normalizer and applies it.
-//
-// If no normalizer matches, it returns the input event unchanged.
-//
-// If a normalizer returns (nil, nil), the event is dropped.
-func (r *Registry) Normalize(ctx context.Context, in event.Event) (*event.Event, error) {
-	if r == nil {
-		// Nil registry is a valid "feature off" state.
-		out := in
-		return &out, nil
-	}
-
-	r.mu.RLock()
-	ns := append([]Normalizer(nil), r.ns...) // copy for safe iteration outside lock
-	r.mu.RUnlock()
-
-	for _, n := range ns {
-		if n == nil {
-			// Shouldn't happen (Register panics), but guard anyway.
-			continue
-		}
-		if !n.Match(in) {
-			continue
-		}
-
-		out, err := n.Normalize(ctx, in)
-		if err != nil {
-			return nil, fmt.Errorf("normalize: normalizer failed: %w", err)
-		}
-		// out may be nil to signal "drop".
-		return out, nil
-	}
-
-	// No match: pass through unchanged.
-	out := in
-	return &out, nil
-}
-
-// Processor adapts a Registry into a pipeline Processor.
-//
-// It implements:
-//
-//	Process(ctx context.Context, in event.Event) (*event.Event, error)
-//
-// which matches feedkit/pipeline.Processor.
-//
-// Optionality:
-//   - If Registry is nil, Processor becomes a no-op pass-through.
-//   - If Registry has no matching normalizer for an event, that event passes through unchanged.
-type Processor struct {
-	Registry *Registry
-
-	// If true, events that do not match any normalizer cause an error.
-	// Default is false (pass-through), which is the behavior you asked for.
-	RequireMatch bool
-}
-
-// Process implements the pipeline.Processor interface.
-func (p Processor) Process(ctx context.Context, in event.Event) (*event.Event, error) {
-	// "Feature off": no registry means no normalization.
-	if p.Registry == nil {
-		out := in
-		return &out, nil
-	}
-
-	out, err := p.Registry.Normalize(ctx, in)
-	if err != nil {
-		return nil, err
-	}
-
-	if out == nil {
-		// Dropped by normalization policy.
-		return nil, nil
-	}
-
-	if p.RequireMatch {
-		// Detect "no-op pass-through due to no match" by checking whether a match existed.
-		// We do this with a cheap second pass to avoid changing Normalize()'s signature.
-		// (This is rare to enable; correctness/clarity > micro-optimization.)
-		if !p.Registry.hasMatch(in) {
-			return nil, fmt.Errorf("normalize: no normalizer matched event (id=%s kind=%s source=%s schema=%q)",
-				in.ID, in.Kind, in.Source, in.Schema)
-		}
-	}
-
-	return out, nil
-}
-
-func (r *Registry) hasMatch(in event.Event) bool {
-	if r == nil {
-		return false
-	}
-	r.mu.RLock()
-	defer r.mu.RUnlock()
-	for _, n := range r.ns {
-		if n != nil && n.Match(in) {
-			return true
-		}
-	}
-	return false
-}

pipeline/dedupe.go

@@ -1,5 +0,0 @@
-package pipeline
-
-// Placeholder for dedupe processor:
-// - key by Event.ID or computed key
-// - in-memory store first; later optional Postgres-backed

pipeline/pipeline.go

@@ -5,15 +5,11 @@ import (
 	"fmt"
 
 	"gitea.maximumdirect.net/ejr/feedkit/event"
+	"gitea.maximumdirect.net/ejr/feedkit/processors"
 )
 
-// Processor can mutate/drop events (dedupe, rate-limit, normalization tweaks).
-type Processor interface {
-	Process(ctx context.Context, in event.Event) (out *event.Event, err error)
-}
-
 type Pipeline struct {
-	Processors []Processor
+	Processors []processors.Processor
 }
 
 func (p *Pipeline) Process(ctx context.Context, e event.Event) (*event.Event, error) {

pipeline/pipeline_test.go

@@ -0,0 +1,115 @@
+package pipeline
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+	"gitea.maximumdirect.net/ejr/feedkit/processors"
+)
+
+type procFunc func(context.Context, event.Event) (*event.Event, error)
+
+func (f procFunc) Process(ctx context.Context, in event.Event) (*event.Event, error) {
+	return f(ctx, in)
+}
+
+func TestPipelineProcessSequentialOrder(t *testing.T) {
+	var gotOrder []string
+
+	p := &Pipeline{
+		Processors: []processors.Processor{
+			procFunc(func(_ context.Context, in event.Event) (*event.Event, error) {
+				gotOrder = append(gotOrder, "first")
+				out := in
+				out.Schema = "stage.one.v1"
+				return &out, nil
+			}),
+			procFunc(func(_ context.Context, in event.Event) (*event.Event, error) {
+				gotOrder = append(gotOrder, "second")
+				if in.Schema != "stage.one.v1" {
+					return nil, fmt.Errorf("expected schema from first stage, got %q", in.Schema)
+				}
+				out := in
+				out.Schema = "stage.two.v1"
+				return &out, nil
+			}),
+		},
+	}
+
+	out, err := p.Process(context.Background(), validEvent())
+	if err != nil {
+		t.Fatalf("Process error: %v", err)
+	}
+	if out == nil {
+		t.Fatalf("expected output event, got nil")
+	}
+	if out.Schema != "stage.two.v1" {
+		t.Fatalf("unexpected output schema: %q", out.Schema)
+	}
+	if strings.Join(gotOrder, ",") != "first,second" {
+		t.Fatalf("unexpected processor order: %v", gotOrder)
+	}
+}
+
+func TestPipelineProcessInvalidInput(t *testing.T) {
+	p := &Pipeline{}
+	_, err := p.Process(context.Background(), event.Event{})
+	if err == nil {
+		t.Fatalf("expected input validation error")
+	}
+	if !strings.Contains(err.Error(), "invalid input event") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestPipelineProcessDrop(t *testing.T) {
+	p := &Pipeline{
+		Processors: []processors.Processor{
+			procFunc(func(context.Context, event.Event) (*event.Event, error) {
+				return nil, nil
+			}),
+		},
+	}
+
+	out, err := p.Process(context.Background(), validEvent())
+	if err != nil {
+		t.Fatalf("Process error: %v", err)
+	}
+	if out != nil {
+		t.Fatalf("expected nil output for dropped event, got %#v", out)
+	}
+}
+
+func TestPipelineProcessInvalidOutput(t *testing.T) {
+	p := &Pipeline{
+		Processors: []processors.Processor{
+			procFunc(func(_ context.Context, in event.Event) (*event.Event, error) {
+				out := in
+				out.Payload = nil
+				return &out, nil
+			}),
+		},
+	}
+
+	_, err := p.Process(context.Background(), validEvent())
+	if err == nil {
+		t.Fatalf("expected output validation error")
+	}
+	if !strings.Contains(err.Error(), "invalid output event") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func validEvent() event.Event {
+	return event.Event{
+		ID:        "evt-1",
+		Kind:      event.Kind("observation"),
+		Source:    "source-1",
+		EmittedAt: time.Now().UTC(),
+		Payload:   map[string]any{"ok": true},
+	}
+}

pipeline/ratelimit.go

@@ -1,5 +0,0 @@
-package pipeline
-
-// Placeholder for rate limit processor:
-// - per source/kind sink routing limits
-// - cooldown windows

processors/dedupe/doc.go

@@ -0,0 +1,28 @@
+// Package dedupe provides a default in-memory LRU deduplication processor.
+//
+// The processor keys strictly by event.Event.ID:
+//   - first-seen IDs pass through
+//   - repeated IDs are dropped
+//
+// The in-memory seen-ID set is bounded by a required maxEntries capacity.
+// When capacity is exceeded, the least recently used ID is evicted.
+//
+// Typical registry wiring:
+//
+// ```go
+// reg := processors.NewRegistry()
+// reg.Register("dedupe", dedupe.Factory(10_000))
+//
+//	reg.Register("normalize", func() (processors.Processor, error) {
+//	    return normalize.NewProcessor(myNormalizers, false), nil
+//	})
+//
+// chain, err := reg.BuildChain([]string{"dedupe", "normalize"})
+//
+//	if err != nil {
+//	    // handle wiring error
+//	}
+//
+// p := &pipeline.Pipeline{Processors: chain}
+// ```
+package dedupe

processors/dedupe/processor.go

@@ -0,0 +1,89 @@
+package dedupe
+
+import (
+	"container/list"
+	"context"
+	"fmt"
+	"strings"
+	"sync"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+	"gitea.maximumdirect.net/ejr/feedkit/processors"
+)
+
+// Processor drops duplicate events by Event.ID using an in-memory LRU.
+type Processor struct {
+	maxEntries int
+
+	mu    sync.Mutex
+	order *list.List               // most-recent at front, least-recent at back
+	byID  map[string]*list.Element // id -> list element (element.Value is string id)
+}
+
+var _ processors.Processor = (*Processor)(nil)
+
+// NewProcessor constructs a dedupe processor with a required max entry count.
+func NewProcessor(maxEntries int) (*Processor, error) {
+	if maxEntries <= 0 {
+		return nil, fmt.Errorf("dedupe: maxEntries must be > 0, got %d", maxEntries)
+	}
+
+	return &Processor{
+		maxEntries: maxEntries,
+		order:      list.New(),
+		byID:       make(map[string]*list.Element, maxEntries),
+	}, nil
+}
+
+// Factory returns a processors.Factory that constructs Processor instances.
+func Factory(maxEntries int) processors.Factory {
+	return func() (processors.Processor, error) {
+		return NewProcessor(maxEntries)
+	}
+}
+
+// Process implements processors.Processor.
+func (p *Processor) Process(_ context.Context, in event.Event) (*event.Event, error) {
+	if p == nil {
+		return nil, fmt.Errorf("dedupe: processor is nil")
+	}
+	if p.maxEntries <= 0 {
+		return nil, fmt.Errorf("dedupe: processor maxEntries must be > 0")
+	}
+
+	id := strings.TrimSpace(in.ID)
+	if id == "" {
+		return nil, fmt.Errorf("dedupe: event ID is required")
+	}
+
+	p.mu.Lock()
+
+	if p.order == nil || p.byID == nil {
+		p.mu.Unlock()
+		return nil, fmt.Errorf("dedupe: processor is not initialized")
+	}
+
+	if elem, exists := p.byID[id]; exists {
+		p.order.MoveToFront(elem)
+		p.mu.Unlock()
+		return nil, nil
+	}
+
+	elem := p.order.PushFront(id)
+	p.byID[id] = elem
+
+	if p.order.Len() > p.maxEntries {
+		oldest := p.order.Back()
+		if oldest != nil {
+			p.order.Remove(oldest)
+			if oldestID, ok := oldest.Value.(string); ok {
+				delete(p.byID, oldestID)
+			}
+		}
+	}
+
+	p.mu.Unlock()
+
+	out := in
+	return &out, nil
+}

processors/dedupe/processor_test.go

@@ -0,0 +1,163 @@
+package dedupe
+
+import (
+	"context"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+	"gitea.maximumdirect.net/ejr/feedkit/processors"
+)
+
+func TestNewProcessorValidation(t *testing.T) {
+	t.Run("rejects non-positive maxEntries", func(t *testing.T) {
+		for _, maxEntries := range []int{0, -1} {
+			p, err := NewProcessor(maxEntries)
+			if err == nil {
+				t.Fatalf("expected error for maxEntries=%d, got nil", maxEntries)
+			}
+			if p != nil {
+				t.Fatalf("expected nil processor for maxEntries=%d", maxEntries)
+			}
+			if !strings.Contains(err.Error(), "maxEntries") {
+				t.Fatalf("unexpected error: %v", err)
+			}
+		}
+	})
+
+	t.Run("accepts positive maxEntries", func(t *testing.T) {
+		p, err := NewProcessor(1)
+		if err != nil {
+			t.Fatalf("NewProcessor error: %v", err)
+		}
+		if p == nil {
+			t.Fatalf("expected processor, got nil")
+		}
+	})
+}
+
+func TestProcessorFirstSeenAndDuplicate(t *testing.T) {
+	p, err := NewProcessor(8)
+	if err != nil {
+		t.Fatalf("NewProcessor error: %v", err)
+	}
+
+	ctx := context.Background()
+	first := testEvent("evt-1")
+
+	out, err := p.Process(ctx, first)
+	if err != nil {
+		t.Fatalf("Process first error: %v", err)
+	}
+	if out == nil {
+		t.Fatalf("expected first event to pass through")
+	}
+	if out.ID != first.ID {
+		t.Fatalf("expected unchanged ID %q, got %q", first.ID, out.ID)
+	}
+
+	out, err = p.Process(ctx, first)
+	if err != nil {
+		t.Fatalf("Process duplicate error: %v", err)
+	}
+	if out != nil {
+		t.Fatalf("expected duplicate to be dropped, got %#v", out)
+	}
+
+	out, err = p.Process(ctx, testEvent("evt-2"))
+	if err != nil {
+		t.Fatalf("Process second unique error: %v", err)
+	}
+	if out == nil {
+		t.Fatalf("expected second unique event to pass through")
+	}
+}
+
+func TestProcessorLRUEvictionAndPromotion(t *testing.T) {
+	p, err := NewProcessor(2)
+	if err != nil {
+		t.Fatalf("NewProcessor error: %v", err)
+	}
+
+	ctx := context.Background()
+
+	mustPass(t, p, ctx, "a")
+	mustPass(t, p, ctx, "b")
+	mustDrop(t, p, ctx, "a") // promote "a" so "b" becomes least-recently-used
+	mustPass(t, p, ctx, "c") // evicts "b"
+	mustDrop(t, p, ctx, "a") // "a" should still be tracked after promotion
+	mustPass(t, p, ctx, "b") // "b" was evicted, so now it passes again
+}
+
+func TestProcessorRejectsBlankID(t *testing.T) {
+	p, err := NewProcessor(4)
+	if err != nil {
+		t.Fatalf("NewProcessor error: %v", err)
+	}
+
+	in := testEvent("   ")
+	out, err := p.Process(context.Background(), in)
+	if err == nil {
+		t.Fatalf("expected error for blank ID")
+	}
+	if out != nil {
+		t.Fatalf("expected nil output on error, got %#v", out)
+	}
+	if !strings.Contains(err.Error(), "event ID is required") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestFactoryWithRegistry(t *testing.T) {
+	r := processors.NewRegistry()
+	r.Register("dedupe", Factory(3))
+
+	p, err := r.Build("dedupe")
+	if err != nil {
+		t.Fatalf("Build error: %v", err)
+	}
+	if p == nil {
+		t.Fatalf("expected processor, got nil")
+	}
+
+	out, err := p.Process(context.Background(), testEvent("evt-factory-1"))
+	if err != nil {
+		t.Fatalf("Process error: %v", err)
+	}
+	if out == nil {
+		t.Fatalf("expected first event to pass through")
+	}
+}
+
+func mustPass(t *testing.T, p *Processor, ctx context.Context, id string) {
+	t.Helper()
+	out, err := p.Process(ctx, testEvent(id))
+	if err != nil {
+		t.Fatalf("expected pass for id=%q, got error: %v", id, err)
+	}
+	if out == nil {
+		t.Fatalf("expected pass for id=%q, got drop", id)
+	}
+}
+
+func mustDrop(t *testing.T, p *Processor, ctx context.Context, id string) {
+	t.Helper()
+	out, err := p.Process(ctx, testEvent(id))
+	if err != nil {
+		t.Fatalf("expected drop for id=%q, got error: %v", id, err)
+	}
+	if out != nil {
+		t.Fatalf("expected drop for id=%q, got output", id)
+	}
+}
+
+func testEvent(id string) event.Event {
+	return event.Event{
+		ID:        id,
+		Kind:      event.Kind("observation"),
+		Source:    "source-1",
+		EmittedAt: time.Now().UTC(),
+		Payload:   map[string]any{"ok": true},
+	}
+}

processors/doc.go

@@ -0,0 +1,24 @@
+// Package processors defines feedkit's generic processor abstraction and registry.
+//
+// Processors are optional pipeline stages that can transform, drop, or reject
+// events before dispatch to sinks.
+//
+// Registry provides name-based construction so daemons can assemble processor
+// chains without embedding switch statements in wiring code.
+//
+// Example:
+//
+//	reg := processors.NewRegistry()
+//	reg.Register("dedupe", dedupe.Factory(10_000))
+//	reg.Register("normalize", func() (processors.Processor, error) {
+//	    // import "gitea.maximumdirect.net/ejr/feedkit/processors/normalize"
+//	    return normalize.NewProcessor(myNormalizers, false), nil
+//	})
+//
+//	chain, err := reg.BuildChain([]string{"dedupe", "normalize"})
+//	if err != nil {
+//	    // handle wiring error
+//	}
+//
+//	p := &pipeline.Pipeline{Processors: chain}
+package processors

processors/normalize/doc.go

@@ -0,0 +1,19 @@
+// Package normalize provides the feedkit normalization processor and related
+// helper APIs for raw-to-canonical event mapping.
+//
+// External API surface:
+//   - Processor: concrete processors.Processor implementation
+//   - Normalizer / Func: normalization interface and ergonomic function adapter
+//
+// Optional helpers from helpers.go:
+//   - PayloadJSONBytes: extract supported JSON-shaped payloads into bytes
+//   - DecodeJSONPayload: decode an event payload into a typed struct
+//   - FinalizeEvent: copy the input event envelope onto a normalized output
+//
+// Typical usage:
+// sources emit raw events (often with json.RawMessage payloads), then a
+// normalize.Processor converts matching raw schemas into canonical payloads.
+//
+// Key property: normalization is optional.
+// If no Normalizer matches an event, Processor passes it through unchanged by default.
+package normalize

processors/normalize/helpers.go

@@ -0,0 +1,84 @@
+package normalize
+
+import (
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+// PayloadJSONBytes extracts a JSON payload into bytes suitable for json.Unmarshal.
+//
+// Supported payload shapes:
+//   - json.RawMessage
+//   - []byte
+//   - string
+//   - map[string]any
+func PayloadJSONBytes(e event.Event) ([]byte, error) {
+	if e.Payload == nil {
+		return nil, fmt.Errorf("payload is nil")
+	}
+
+	switch v := e.Payload.(type) {
+	case json.RawMessage:
+		if len(v) == 0 {
+			return nil, fmt.Errorf("payload is empty json.RawMessage")
+		}
+		return []byte(v), nil
+	case []byte:
+		if len(v) == 0 {
+			return nil, fmt.Errorf("payload is empty []byte")
+		}
+		return v, nil
+	case string:
+		if v == "" {
+			return nil, fmt.Errorf("payload is empty string")
+		}
+		return []byte(v), nil
+	case map[string]any:
+		b, err := json.Marshal(v)
+		if err != nil {
+			return nil, fmt.Errorf("marshal map payload: %w", err)
+		}
+		return b, nil
+	default:
+		return nil, fmt.Errorf("unsupported payload type %T", e.Payload)
+	}
+}
+
+// DecodeJSONPayload extracts the event payload as bytes and unmarshals it into T.
+func DecodeJSONPayload[T any](in event.Event) (T, error) {
+	var zero T
+
+	b, err := PayloadJSONBytes(in)
+	if err != nil {
+		return zero, fmt.Errorf("extract payload: %w", err)
+	}
+
+	var parsed T
+	if err := json.Unmarshal(b, &parsed); err != nil {
+		return zero, fmt.Errorf("decode raw payload: %w", err)
+	}
+
+	return parsed, nil
+}
+
+// FinalizeEvent builds the output event envelope by copying the input and applying
+// the new schema/payload, plus optional EffectiveAt.
+func FinalizeEvent(in event.Event, outSchema string, outPayload any, effectiveAt time.Time) (*event.Event, error) {
+	out := in
+	out.Schema = outSchema
+	out.Payload = outPayload
+
+	if !effectiveAt.IsZero() {
+		t := effectiveAt.UTC()
+		out.EffectiveAt = &t
+	}
+
+	if err := out.Validate(); err != nil {
+		return nil, err
+	}
+
+	return &out, nil
+}

processors/normalize/helpers_test.go

@@ -0,0 +1,118 @@
+package normalize
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+func TestPayloadJSONBytesSupportedShapes(t *testing.T) {
+	cases := []struct {
+		name    string
+		payload any
+		want    string
+	}{
+		{name: "rawmessage", payload: json.RawMessage(`{"a":1}`), want: `{"a":1}`},
+		{name: "bytes", payload: []byte(`{"a":2}`), want: `{"a":2}`},
+		{name: "string", payload: `{"a":3}`, want: `{"a":3}`},
+		{name: "map", payload: map[string]any{"a": 4}, want: `{"a":4}`},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := PayloadJSONBytes(event.Event{Payload: tc.payload})
+			if err != nil {
+				t.Fatalf("PayloadJSONBytes() unexpected error: %v", err)
+			}
+			if string(got) != tc.want {
+				t.Fatalf("PayloadJSONBytes() = %s, want %s", string(got), tc.want)
+			}
+		})
+	}
+}
+
+func TestPayloadJSONBytesRejectsInvalidPayloads(t *testing.T) {
+	cases := []struct {
+		name    string
+		payload any
+		want    string
+	}{
+		{name: "nil", payload: nil, want: "payload is nil"},
+		{name: "empty rawmessage", payload: json.RawMessage{}, want: "payload is empty json.RawMessage"},
+		{name: "empty bytes", payload: []byte{}, want: "payload is empty []byte"},
+		{name: "empty string", payload: "", want: "payload is empty string"},
+		{name: "unsupported", payload: 123, want: "unsupported payload type"},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err := PayloadJSONBytes(event.Event{Payload: tc.payload})
+			if err == nil {
+				t.Fatalf("PayloadJSONBytes() expected error")
+			}
+			if !strings.Contains(err.Error(), tc.want) {
+				t.Fatalf("PayloadJSONBytes() error = %q, want substring %q", err, tc.want)
+			}
+		})
+	}
+}
+
+func TestDecodeJSONPayload(t *testing.T) {
+	type payload struct {
+		Name string `json:"name"`
+	}
+
+	got, err := DecodeJSONPayload[payload](event.Event{
+		Payload: json.RawMessage(`{"name":"alice"}`),
+	})
+	if err != nil {
+		t.Fatalf("DecodeJSONPayload() unexpected error: %v", err)
+	}
+	if got.Name != "alice" {
+		t.Fatalf("DecodeJSONPayload() = %#v, want name alice", got)
+	}
+}
+
+func TestFinalizeEventPreservesEnvelopeAndEffectiveAtBehavior(t *testing.T) {
+	existingEffectiveAt := time.Date(2026, 3, 28, 11, 0, 0, 0, time.UTC)
+	in := event.Event{
+		ID:          "evt-1",
+		Kind:        event.Kind("observation"),
+		Source:      "source-a",
+		EmittedAt:   time.Date(2026, 3, 28, 12, 0, 0, 0, time.UTC),
+		EffectiveAt: &existingEffectiveAt,
+		Schema:      "raw.example.v1",
+		Payload:     map[string]any{"old": true},
+	}
+
+	out, err := FinalizeEvent(in, "example.v1", map[string]any{"value": 1.234567}, time.Time{})
+	if err != nil {
+		t.Fatalf("FinalizeEvent() unexpected error: %v", err)
+	}
+	if out.ID != in.ID || out.Kind != in.Kind || out.Source != in.Source || out.EmittedAt != in.EmittedAt {
+		t.Fatalf("FinalizeEvent() changed preserved envelope fields: %#v", out)
+	}
+	if out.EffectiveAt == nil || !out.EffectiveAt.Equal(existingEffectiveAt) {
+		t.Fatalf("FinalizeEvent() effectiveAt = %#v, want preserved existing value", out.EffectiveAt)
+	}
+
+	nextEffectiveAt := time.Date(2026, 3, 28, 13, 0, 0, 0, time.FixedZone("x", -4*3600))
+	out, err = FinalizeEvent(in, "example.v1", map[string]any{"value": 1.234567}, nextEffectiveAt)
+	if err != nil {
+		t.Fatalf("FinalizeEvent() unexpected overwrite error: %v", err)
+	}
+	if out.EffectiveAt == nil || !out.EffectiveAt.Equal(nextEffectiveAt.UTC()) {
+		t.Fatalf("FinalizeEvent() effectiveAt = %#v, want %s", out.EffectiveAt, nextEffectiveAt.UTC())
+	}
+
+	payloadMap, ok := out.Payload.(map[string]any)
+	if !ok {
+		t.Fatalf("FinalizeEvent() payload type = %T, want map[string]any", out.Payload)
+	}
+	if payloadMap["value"] != 1.234567 {
+		t.Fatalf("FinalizeEvent() payload value = %#v, want unrounded 1.234567", payloadMap["value"])
+	}
+}

processors/normalize/processor.go

@@ -0,0 +1,57 @@
+package normalize
+
+import (
+	"context"
+	"fmt"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+// Processor applies ordered normalization rules to pipeline events.
+//
+// Selection rule:
+//   - iterate in Normalizers order
+//   - the first Normalizer whose Match returns true is applied
+//
+// If no normalizer matches, the default behavior is pass-through.
+type Processor struct {
+	Normalizers []Normalizer
+
+	// If true, events that do not match any normalizer cause an error.
+	// Default is false (pass-through).
+	RequireMatch bool
+}
+
+// NewProcessor constructs a normalization processor from an ordered normalizer list.
+func NewProcessor(normalizers []Normalizer, requireMatch bool) Processor {
+	return Processor{
+		Normalizers:  append([]Normalizer(nil), normalizers...),
+		RequireMatch: requireMatch,
+	}
+}
+
+// Process implements processors.Processor.
+func (p Processor) Process(ctx context.Context, in event.Event) (*event.Event, error) {
+	for _, n := range p.Normalizers {
+		if n == nil {
+			continue
+		}
+		if !n.Match(in) {
+			continue
+		}
+
+		out, err := n.Normalize(ctx, in)
+		if err != nil {
+			return nil, fmt.Errorf("normalize: normalizer failed: %w", err)
+		}
+		return out, nil
+	}
+
+	if p.RequireMatch {
+		return nil, fmt.Errorf("normalize: no normalizer matched event (id=%s kind=%s source=%s schema=%q)",
+			in.ID, in.Kind, in.Source, in.Schema)
+	}
+
+	out := in
+	return &out, nil
+}

processors/normalize/processor_test.go

@@ -0,0 +1,139 @@
+package normalize
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+func TestProcessorFirstMatchWins(t *testing.T) {
+	var firstCalls, secondCalls int
+
+	p := NewProcessor([]Normalizer{
+		Func{
+			MatchFn: func(event.Event) bool { return true },
+			NormalizeFn: func(_ context.Context, in event.Event) (*event.Event, error) {
+				firstCalls++
+				out := in
+				out.Schema = "normalized.first.v1"
+				return &out, nil
+			},
+		},
+		Func{
+			MatchFn: func(event.Event) bool { return true },
+			NormalizeFn: func(_ context.Context, in event.Event) (*event.Event, error) {
+				secondCalls++
+				out := in
+				out.Schema = "normalized.second.v1"
+				return &out, nil
+			},
+		},
+	}, false)
+
+	out, err := p.Process(context.Background(), testEvent())
+	if err != nil {
+		t.Fatalf("Process error: %v", err)
+	}
+	if out == nil {
+		t.Fatalf("expected output event, got nil")
+	}
+	if out.Schema != "normalized.first.v1" {
+		t.Fatalf("unexpected schema: %q", out.Schema)
+	}
+	if firstCalls != 1 {
+		t.Fatalf("expected first normalizer called once, got %d", firstCalls)
+	}
+	if secondCalls != 0 {
+		t.Fatalf("expected second normalizer skipped, got %d calls", secondCalls)
+	}
+}
+
+func TestProcessorNoMatchPassThroughAndRequireMatch(t *testing.T) {
+	in := testEvent()
+	in.Schema = "raw.schema.v1"
+
+	passThrough := NewProcessor([]Normalizer{
+		Func{
+			MatchFn: func(event.Event) bool { return false },
+			NormalizeFn: func(_ context.Context, in event.Event) (*event.Event, error) {
+				out := in
+				out.Schema = "should.not.run"
+				return &out, nil
+			},
+		},
+	}, false)
+
+	out, err := passThrough.Process(context.Background(), in)
+	if err != nil {
+		t.Fatalf("pass-through Process error: %v", err)
+	}
+	if out == nil {
+		t.Fatalf("expected pass-through output event, got nil")
+	}
+	if out.Schema != "raw.schema.v1" {
+		t.Fatalf("expected unchanged schema, got %q", out.Schema)
+	}
+
+	required := NewProcessor(nil, true)
+	_, err = required.Process(context.Background(), in)
+	if err == nil {
+		t.Fatalf("expected require-match error")
+	}
+	if !strings.Contains(err.Error(), "no normalizer matched") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestProcessorDropAndErrorPropagation(t *testing.T) {
+	t.Run("drop", func(t *testing.T) {
+		p := NewProcessor([]Normalizer{
+			Func{
+				MatchFn: func(event.Event) bool { return true },
+				NormalizeFn: func(context.Context, event.Event) (*event.Event, error) {
+					return nil, nil
+				},
+			},
+		}, false)
+
+		out, err := p.Process(context.Background(), testEvent())
+		if err != nil {
+			t.Fatalf("Process error: %v", err)
+		}
+		if out != nil {
+			t.Fatalf("expected nil output for dropped event, got %#v", out)
+		}
+	})
+
+	t.Run("error", func(t *testing.T) {
+		p := NewProcessor([]Normalizer{
+			Func{
+				MatchFn: func(event.Event) bool { return true },
+				NormalizeFn: func(context.Context, event.Event) (*event.Event, error) {
+					return nil, errors.New("map failed")
+				},
+			},
+		}, false)
+
+		_, err := p.Process(context.Background(), testEvent())
+		if err == nil {
+			t.Fatalf("expected error")
+		}
+		if !strings.Contains(err.Error(), "normalizer failed") {
+			t.Fatalf("unexpected error: %v", err)
+		}
+	})
+}
+
+func testEvent() event.Event {
+	return event.Event{
+		ID:        "evt-normalize-1",
+		Kind:      event.Kind("observation"),
+		Source:    "source-1",
+		EmittedAt: time.Now().UTC(),
+		Payload:   map[string]any{"x": 1},
+	}
+}

processors/processor.go

@@ -0,0 +1,15 @@
+package processors
+
+import (
+	"context"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+// Processor can mutate/drop events (dedupe, rate-limit, normalization tweaks).
+type Processor interface {
+	Process(ctx context.Context, in event.Event) (out *event.Event, err error)
+}
+
+// Factory constructs a configured Processor instance.
+type Factory func() (Processor, error)

processors/registry.go

@@ -0,0 +1,71 @@
+package processors
+
+import (
+	"fmt"
+	"strings"
+)
+
+type Registry struct {
+	byDriver map[string]Factory
+}
+
+func NewRegistry() *Registry {
+	return &Registry{byDriver: map[string]Factory{}}
+}
+
+// Register associates a processor driver name with a factory.
+//
+// Register panics for empty driver names, nil factories, and duplicates.
+func (r *Registry) Register(driver string, f Factory) {
+	if r == nil {
+		panic("processors.Registry.Register: registry cannot be nil")
+	}
+	driver = strings.TrimSpace(driver)
+	if driver == "" {
+		panic("processors.Registry.Register: driver cannot be empty")
+	}
+	if f == nil {
+		panic(fmt.Sprintf("processors.Registry.Register: factory cannot be nil (driver=%q)", driver))
+	}
+	if r.byDriver == nil {
+		r.byDriver = map[string]Factory{}
+	}
+	if _, exists := r.byDriver[driver]; exists {
+		panic(fmt.Sprintf("processors.Registry.Register: driver %q already registered", driver))
+	}
+	r.byDriver[driver] = f
+}
+
+// Build constructs a Processor by driver name.
+func (r *Registry) Build(driver string) (Processor, error) {
+	if r == nil {
+		return nil, fmt.Errorf("processors registry is nil")
+	}
+	driver = strings.TrimSpace(driver)
+	f, ok := r.byDriver[driver]
+	if !ok {
+		return nil, fmt.Errorf("unknown processor driver: %q", driver)
+	}
+
+	p, err := f()
+	if err != nil {
+		return nil, fmt.Errorf("build processor %q: %w", driver, err)
+	}
+	if p == nil {
+		return nil, fmt.Errorf("build processor %q: factory returned nil processor", driver)
+	}
+	return p, nil
+}
+
+// BuildChain constructs an ordered processor chain from a driver list.
+func (r *Registry) BuildChain(drivers []string) ([]Processor, error) {
+	out := make([]Processor, 0, len(drivers))
+	for i, driver := range drivers {
+		p, err := r.Build(driver)
+		if err != nil {
+			return nil, fmt.Errorf("build processor chain[%d] (%q): %w", i, strings.TrimSpace(driver), err)
+		}
+		out = append(out, p)
+	}
+	return out, nil
+}

processors/registry_test.go

@@ -0,0 +1,100 @@
+package processors
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+type testProcessor struct {
+	name string
+}
+
+func (p testProcessor) Process(context.Context, event.Event) (*event.Event, error) {
+	return nil, nil
+}
+
+func TestRegistryRegisterValidation(t *testing.T) {
+	t.Run("empty driver panics", func(t *testing.T) {
+		r := NewRegistry()
+		assertPanics(t, func() {
+			r.Register("   ", func() (Processor, error) { return testProcessor{name: "x"}, nil })
+		})
+	})
+
+	t.Run("nil factory panics", func(t *testing.T) {
+		r := NewRegistry()
+		assertPanics(t, func() {
+			r.Register("normalize", nil)
+		})
+	})
+
+	t.Run("duplicate driver panics", func(t *testing.T) {
+		r := NewRegistry()
+		r.Register("normalize", func() (Processor, error) { return testProcessor{name: "a"}, nil })
+		assertPanics(t, func() {
+			r.Register("normalize", func() (Processor, error) { return testProcessor{name: "b"}, nil })
+		})
+	})
+}
+
+func TestRegistryBuildUnknownDriver(t *testing.T) {
+	r := NewRegistry()
+	_, err := r.Build("does_not_exist")
+	if err == nil {
+		t.Fatalf("expected error for unknown driver")
+	}
+	if !strings.Contains(err.Error(), "unknown processor driver") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestRegistryBuildChainPreservesOrder(t *testing.T) {
+	r := NewRegistry()
+	r.Register("first", func() (Processor, error) { return testProcessor{name: "first"}, nil })
+	r.Register("second", func() (Processor, error) { return testProcessor{name: "second"}, nil })
+
+	chain, err := r.BuildChain([]string{"first", "second"})
+	if err != nil {
+		t.Fatalf("BuildChain error: %v", err)
+	}
+	if len(chain) != 2 {
+		t.Fatalf("expected 2 processors, got %d", len(chain))
+	}
+
+	p0, ok := chain[0].(testProcessor)
+	if !ok || p0.name != "first" {
+		t.Fatalf("unexpected chain[0]: %#v", chain[0])
+	}
+	p1, ok := chain[1].(testProcessor)
+	if !ok || p1.name != "second" {
+		t.Fatalf("unexpected chain[1]: %#v", chain[1])
+	}
+}
+
+func TestRegistryBuildChainIndexedFailure(t *testing.T) {
+	r := NewRegistry()
+	r.Register("ok", func() (Processor, error) { return testProcessor{name: "ok"}, nil })
+	r.Register("broken", func() (Processor, error) { return nil, errors.New("boom") })
+
+	_, err := r.BuildChain([]string{"ok", "broken"})
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+	if !strings.Contains(err.Error(), "chain[1]") {
+		t.Fatalf("expected indexed error, got: %v", err)
+	}
+}
+
+func assertPanics(t *testing.T, fn func()) {
+	t.Helper()
+	defer func() {
+		if recover() == nil {
+			t.Fatalf("expected panic")
+		}
+	}()
+	fn()
+}

scheduler/scheduler.go

@@ -17,15 +17,27 @@ import (
 // one function everywhere without type mismatch friction.
 type Logger = logging.Logf
 
+// Job describes one scheduler task.
+//
+// A Job may be backed by either:
+//   - a polling source (sources.PollSource): uses Every + jitter and calls Poll()
+//   - a stream source (sources.StreamSource): ignores Every and calls Run()
+//
+// Jitter behavior:
+//   - For polling sources: Jitter is applied at startup and before each poll tick.
+//   - For stream sources: Jitter is applied once at startup only (optional; useful to avoid
+//     reconnect storms when many instances start together).
 type Job struct {
-	Source sources.Source
+	Source sources.Input
 	Every  time.Duration
 
 	// Jitter is the maximum additional delay added before each poll.
 	// Example: if Every=15m and Jitter=30s, each poll will occur at:
 	//   tick time + random(0..30s)
 	//
-	// If Jitter == 0, we compute a default jitter based on Every.
+	// If Jitter == 0 for polling sources, we compute a default jitter based on Every.
+	//
+	// For stream sources, Jitter is treated as *startup jitter only*.
 	Jitter time.Duration
 }
 
@@ -35,8 +47,9 @@ type Scheduler struct {
 	Logf Logger
 }
 
-// Run starts one polling goroutine per job.
-// Each job runs on its own interval and emits 0..N events per poll.
+// Run starts one goroutine per job.
+// Poll jobs run on their own interval and emit 0..N events per poll.
+// Stream jobs run continuously and emit events as they arrive.
 func (s *Scheduler) Run(ctx context.Context) error {
 	if s.Out == nil {
 		return fmt.Errorf("scheduler.Run: Out channel is nil")
@@ -59,17 +72,48 @@ func (s *Scheduler) runJob(ctx context.Context, job Job) {
 		s.logf("scheduler: job has nil source")
 		return
 	}
-	if job.Every <= 0 {
-		s.logf("scheduler: job %s has invalid interval", job.Source.Name())
+
+	// Stream sources: event-driven.
+	if ss, ok := job.Source.(sources.StreamSource); ok {
+		s.runStream(ctx, job, ss)
 		return
 	}
 
+	// Poll sources: time-based.
+	ps, ok := job.Source.(sources.PollSource)
+	if !ok {
+		s.logf("scheduler: source %T (%s) implements neither Poll() nor Run()", job.Source, job.Source.Name())
+		return
+	}
+	if job.Every <= 0 {
+		s.logf("scheduler: polling job %q missing/invalid interval (sources[].every)", ps.Name())
+		return
+	}
+
+	s.runPoller(ctx, job, ps)
+}
+
+func (s *Scheduler) runStream(ctx context.Context, job Job, src sources.StreamSource) {
+	// Optional startup jitter: helps avoid reconnect storms if many daemons start at once.
+	if job.Jitter > 0 {
+		rng := seededRNG(src.Name())
+		if !sleepJitter(ctx, rng, job.Jitter) {
+			return
+		}
+	}
+
+	// Stream sources should block until ctx cancel or fatal error.
+	if err := src.Run(ctx, s.Out); err != nil && ctx.Err() == nil {
+		s.logf("scheduler: stream source %q exited with error: %v", src.Name(), err)
+	}
+}
+
+func (s *Scheduler) runPoller(ctx context.Context, job Job, src sources.PollSource) {
 	// Compute jitter: either configured per job, or a sensible default.
 	jitter := effectiveJitter(job.Every, job.Jitter)
 
 	// Each worker gets its own RNG (safe + no lock contention).
-	seed := time.Now().UnixNano() ^ int64(hashStringFNV32a(job.Source.Name()))
-	rng := rand.New(rand.NewSource(seed))
+	rng := seededRNG(src.Name())
 
 	// Optional startup jitter: avoids all jobs firing at the exact moment the daemon starts.
 	if !sleepJitter(ctx, rng, jitter) {
@@ -77,7 +121,7 @@ func (s *Scheduler) runJob(ctx context.Context, job Job) {
 	}
 
 	// Immediate poll at startup (after startup jitter).
-	s.pollOnce(ctx, job)
+	s.pollOnce(ctx, src)
 
 	t := time.NewTicker(job.Every)
 	defer t.Stop()
@@ -89,7 +133,7 @@ func (s *Scheduler) runJob(ctx context.Context, job Job) {
 			if !sleepJitter(ctx, rng, jitter) {
 				return
 			}
-			s.pollOnce(ctx, job)
+			s.pollOnce(ctx, src)
 
 		case <-ctx.Done():
 			return
@@ -97,10 +141,10 @@ func (s *Scheduler) runJob(ctx context.Context, job Job) {
 	}
 }
 
-func (s *Scheduler) pollOnce(ctx context.Context, job Job) {
-	events, err := job.Source.Poll(ctx)
+func (s *Scheduler) pollOnce(ctx context.Context, src sources.PollSource) {
+	events, err := src.Poll(ctx)
 	if err != nil {
-		s.logf("scheduler: poll failed (%s): %v", job.Source.Name(), err)
+		s.logf("scheduler: poll failed (%s): %v", src.Name(), err)
 		return
 	}
 
@@ -120,6 +164,13 @@ func (s *Scheduler) logf(format string, args ...any) {
 	s.Logf(format, args...)
 }
 
+// ---- helpers ----
+
+func seededRNG(name string) *rand.Rand {
+	seed := time.Now().UnixNano() ^ int64(hashStringFNV32a(name))
+	return rand.New(rand.NewSource(seed))
+}
+
 // effectiveJitter chooses a jitter value.
 // - If configuredMax > 0, use it (but clamp).
 // - Else default to min(every/10, 30s).

scheduler/worker.go

@@ -1,7 +0,0 @@
-package scheduler
-
-// Placeholder for per-source worker logic:
-// - ticker loop
-// - jitter
-// - backoff on errors
-// - emits events into scheduler.Out

sinks/builtins.go

@@ -1,11 +1,6 @@
 package sinks
 
-import (
-	"fmt"
-	"strings"
-
-	"gitea.maximumdirect.net/ejr/feedkit/config"
-)
+import "gitea.maximumdirect.net/ejr/feedkit/config"
 
 // RegisterBuiltins registers sink drivers included in this binary.
 //
@@ -17,39 +12,8 @@ func RegisterBuiltins(r *Registry) {
 		return NewStdoutSink(cfg.Name), nil
 	})
 
-	// File sink: writes/archives events somewhere on disk.
-	r.Register("file", func(cfg config.SinkConfig) (Sink, error) {
-		return NewFileSinkFromConfig(cfg)
-	})
-
-	// Postgres sink: persists events durably.
-	r.Register("postgres", func(cfg config.SinkConfig) (Sink, error) {
-		return NewPostgresSinkFromConfig(cfg)
-	})
-
-	// RabbitMQ sink: publishes events to a broker for downstream consumers.
-	r.Register("rabbitmq", func(cfg config.SinkConfig) (Sink, error) {
-		return NewRabbitMQSinkFromConfig(cfg)
+	// NATS sink: publishes events to a broker for downstream consumers.
+	r.Register("nats", func(cfg config.SinkConfig) (Sink, error) {
+		return NewNATSSinkFromConfig(cfg)
 	})
 }
-
-// ---- helpers for validating sink params ----
-//
-// These helpers live in sinks (not config) on purpose:
-// - config is domain-agnostic and should not embed driver-specific validation helpers.
-// - sinks are adapters; validating their own params here keeps the logic near the driver.
-
-func requireStringParam(cfg config.SinkConfig, key string) (string, error) {
-	v, ok := cfg.Params[key]
-	if !ok {
-		return "", fmt.Errorf("sink %q: params.%s is required", cfg.Name, key)
-	}
-	s, ok := v.(string)
-	if !ok {
-		return "", fmt.Errorf("sink %q: params.%s must be a string", cfg.Name, key)
-	}
-	if strings.TrimSpace(s) == "" {
-		return "", fmt.Errorf("sink %q: params.%s cannot be empty", cfg.Name, key)
-	}
-	return s, nil
-}

sinks/doc.go

@@ -0,0 +1,101 @@
+// Package sinks defines the feedkit sink interface, sink driver registry, and
+// built-in infrastructure sinks.
+//
+// External API surface:
+//   - Sink: adapter interface that consumes event.Event values
+//   - Registry / NewRegistry: named sink factory registry
+//   - RegisterBuiltins: registers the schema-free built-in sink drivers
+//
+// Built-in sink implementations:
+//   - stdout
+//   - nats
+//   - postgres
+//
+// Optional helpers from helpers.go:
+//   - PostgresFactory: returns a sink factory for the built-in Postgres sink
+//     using a provided downstream schema
+//
+// # NATS built-in overview
+//
+// The NATS sink publishes each event as JSON to a configured subject.
+//
+// Required params:
+//   - url: NATS server URL (for example, nats://localhost:4222)
+//   - subject: NATS subject to publish to
+//
+// Example config:
+//
+//	sinks:
+//	  - name: nats_main
+//	    driver: nats
+//	    params:
+//	      url: nats://localhost:4222
+//	      subject: feedkit.events
+//
+// # Postgres built-in overview
+//
+// The postgres sink is intentionally split between downstream daemon ownership
+// and feedkit ownership:
+//   - downstream code registers table schema + event mapping functions
+//   - feedkit manages DB connection, create-if-missing DDL, transactional
+//     inserts, optional automatic retention pruning, and manual prune helpers
+//
+// Example config:
+//
+//	sinks:
+//	  - name: pg_main
+//	    driver: postgres
+//	    params:
+//	      uri: postgres://localhost:5432/feedkit?sslmode=disable
+//	      username: feedkit_user
+//	      password: feedkit_pass
+//	      prune: 3d # optional: prune rows older than now-3d on each write tx
+//
+// params.prune supports:
+//   - Go duration strings (72h, 90m, 30s, ...)
+//   - day/week suffixes (3d, 2w)
+//
+// If params.prune is omitted, automatic pruning is disabled.
+//
+// Example downstream wiring:
+//
+//	sinkReg := sinks.NewRegistry()
+//	sinks.RegisterBuiltins(sinkReg)
+//	sinkReg.Register("postgres", sinks.PostgresFactory(sinks.PostgresSchema{
+//	    Tables: []sinks.PostgresTable{
+//	        {
+//	            Name: "events",
+//	            Columns: []sinks.PostgresColumn{
+//	                {Name: "event_id", Type: "TEXT", Nullable: false},
+//	                {Name: "emitted_at", Type: "TIMESTAMPTZ", Nullable: false},
+//	                {Name: "payload_json", Type: "JSONB", Nullable: false},
+//	            },
+//	            PrimaryKey:  []string{"event_id"},
+//	            PruneColumn: "emitted_at", // required for retention pruning
+//	        },
+//	    },
+//	    MapEvent: func(ctx context.Context, e event.Event) ([]sinks.PostgresWrite, error) {
+//	        b, err := json.Marshal(e.Payload)
+//	        if err != nil {
+//	            return nil, err
+//	        }
+//	        return []sinks.PostgresWrite{
+//	            {
+//	                Table: "events",
+//	                Values: map[string]any{
+//	                    "event_id":     e.ID,
+//	                    "emitted_at":   e.EmittedAt,
+//	                    "payload_json": string(b),
+//	                },
+//	            },
+//	        }, nil
+//	    },
+//	}))
+//
+// Manual pruning via type assertion (administrative helpers):
+//
+//	if p, ok := sink.(sinks.PostgresPruner); ok {
+//	    _, _ = p.PruneKeepLatest(ctx, "events", 10000)
+//	    _, _ = p.PruneOlderThan(ctx, "events", time.Now().UTC().AddDate(0, -1, 0))
+//	}
+package sinks

sinks/file.go

@@ -1,30 +0,0 @@
-package sinks
-
-import (
-	"context"
-	"fmt"
-
-	"gitea.maximumdirect.net/ejr/feedkit/config"
-	"gitea.maximumdirect.net/ejr/feedkit/event"
-)
-
-type FileSink struct {
-	name string
-	path string
-}
-
-func NewFileSinkFromConfig(cfg config.SinkConfig) (Sink, error) {
-	path, err := requireStringParam(cfg, "path")
-	if err != nil {
-		return nil, err
-	}
-	return &FileSink{name: cfg.Name, path: path}, nil
-}
-
-func (s *FileSink) Name() string { return s.name }
-
-func (s *FileSink) Consume(ctx context.Context, e event.Event) error {
-	_ = ctx
-	_ = e
-	return fmt.Errorf("file sink: TODO implement (path=%s)", s.path)
-}

sinks/helpers.go

@@ -0,0 +1,35 @@
+package sinks
+
+import (
+	"fmt"
+	"strings"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+)
+
+// requireStringParam returns a non-empty string sink param.
+//
+// This helper is intentionally local to sinks rather than config so
+// driver-specific validation stays close to the adapters that use it.
+func requireStringParam(cfg config.SinkConfig, key string) (string, error) {
+	v, ok := cfg.Params[key]
+	if !ok {
+		return "", fmt.Errorf("sink %q: params.%s is required", cfg.Name, key)
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("sink %q: params.%s must be a string", cfg.Name, key)
+	}
+	if strings.TrimSpace(s) == "" {
+		return "", fmt.Errorf("sink %q: params.%s cannot be empty", cfg.Name, key)
+	}
+	return s, nil
+}
+
+// PostgresFactory returns a sink factory that builds the built-in Postgres sink
+// using the provided downstream schema definition.
+func PostgresFactory(schema PostgresSchema) Factory {
+	return func(cfg config.SinkConfig) (Sink, error) {
+		return NewPostgresSinkFromConfig(cfg, schema)
+	}
+}

sinks/helpers_test.go

@@ -0,0 +1,46 @@
+package sinks
+
+import (
+	"context"
+	"testing"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+func TestPostgresFactoryReturnsWorkingFactory(t *testing.T) {
+	factory := PostgresFactory(testPostgresSchema())
+	if factory == nil {
+		t.Fatalf("PostgresFactory() returned nil")
+	}
+	if _, err := factory(config.SinkConfig{}); err == nil {
+		t.Fatalf("factory(config) expected parameter validation error")
+	}
+}
+
+func testPostgresSchema() PostgresSchema {
+	return PostgresSchema{
+		Tables: []PostgresTable{
+			{
+				Name: "events",
+				Columns: []PostgresColumn{
+					{Name: "event_id", Type: "TEXT", Nullable: false},
+					{Name: "emitted_at", Type: "TIMESTAMPTZ", Nullable: false},
+				},
+				PrimaryKey:  []string{"event_id"},
+				PruneColumn: "emitted_at",
+			},
+		},
+		MapEvent: func(_ context.Context, e event.Event) ([]PostgresWrite, error) {
+			return []PostgresWrite{
+				{
+					Table: "events",
+					Values: map[string]any{
+						"event_id":   e.ID,
+						"emitted_at": e.EmittedAt,
+					},
+				},
+			}, nil
+		},
+	}
+}

sinks/nats.go

@@ -0,0 +1,97 @@
+package sinks
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"sync"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+	"github.com/nats-io/nats.go"
+)
+
+type NATSSink struct {
+	name    string
+	url     string
+	subject string
+
+	mu   sync.Mutex
+	conn *nats.Conn
+}
+
+func NewNATSSinkFromConfig(cfg config.SinkConfig) (Sink, error) {
+	url, err := requireStringParam(cfg, "url")
+	if err != nil {
+		return nil, err
+	}
+	subject, err := requireStringParam(cfg, "subject")
+	if err != nil {
+		return nil, err
+	}
+	return &NATSSink{name: cfg.Name, url: url, subject: subject}, nil
+}
+
+func (r *NATSSink) Name() string { return r.name }
+
+func (r *NATSSink) Consume(ctx context.Context, e event.Event) error {
+	// Boundary validation: if something upstream violated invariants,
+	// surface it loudly rather than printing partial nonsense.
+	if err := e.Validate(); err != nil {
+		return fmt.Errorf("NATS sink: invalid event: %w", err)
+	}
+
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+
+	conn, err := r.connect(ctx)
+	if err != nil {
+		return fmt.Errorf("NATS sink: connect: %w", err)
+	}
+
+	b, err := json.Marshal(e)
+	if err != nil {
+		return fmt.Errorf("NATS sink: marshal event: %w", err)
+	}
+
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	if err := conn.Publish(r.subject, b); err != nil {
+		return fmt.Errorf("NATS sink: publish: %w", err)
+	}
+	return nil
+}
+
+func (r *NATSSink) connect(ctx context.Context) (*nats.Conn, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if r.conn != nil && r.conn.Status() != nats.CLOSED {
+		return r.conn, nil
+	}
+
+	opts := []nats.Option{
+		nats.Name(fmt.Sprintf("feedkit sink %s", r.name)),
+	}
+	if deadline, ok := ctx.Deadline(); ok {
+		timeout := time.Until(deadline)
+		if timeout <= 0 {
+			return nil, ctx.Err()
+		}
+		opts = append(opts, nats.Timeout(timeout))
+	}
+
+	conn, err := nats.Connect(r.url, opts...)
+	if err != nil {
+		return nil, err
+	}
+	r.conn = conn
+	return conn, nil
+}

sinks/nats_test.go

@@ -0,0 +1,47 @@
+package sinks
+
+import (
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+)
+
+func TestNewNATSSinkFromConfigRequiresSubject(t *testing.T) {
+	sink, err := NewNATSSinkFromConfig(config.SinkConfig{
+		Name:   "nats-main",
+		Driver: "nats",
+		Params: map[string]any{
+			"url":     "nats://localhost:4222",
+			"subject": "feedkit.events",
+		},
+	})
+	if err != nil {
+		t.Fatalf("NewNATSSinkFromConfig() error = %v", err)
+	}
+
+	natsSink, ok := sink.(*NATSSink)
+	if !ok {
+		t.Fatalf("sink type = %T, want *NATSSink", sink)
+	}
+	if natsSink.subject != "feedkit.events" {
+		t.Fatalf("subject = %q, want feedkit.events", natsSink.subject)
+	}
+}
+
+func TestNewNATSSinkFromConfigRejectsLegacyExchange(t *testing.T) {
+	_, err := NewNATSSinkFromConfig(config.SinkConfig{
+		Name:   "nats-main",
+		Driver: "nats",
+		Params: map[string]any{
+			"url":      "nats://localhost:4222",
+			"exchange": "feedkit.events",
+		},
+	})
+	if err == nil {
+		t.Fatalf("NewNATSSinkFromConfig() expected error")
+	}
+	if !strings.Contains(err.Error(), "params.subject is required") {
+		t.Fatalf("error = %q, want params.subject is required", err)
+	}
+}

sinks/postgres.go

@@ -2,36 +2,460 @@ package sinks
 
 import (
 	"context"
+	"database/sql"
 	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
 
 	"gitea.maximumdirect.net/ejr/feedkit/config"
 	"gitea.maximumdirect.net/ejr/feedkit/event"
+	_ "github.com/lib/pq"
 )
 
-type PostgresSink struct {
-	name string
-	dsn  string
+const postgresInitTimeout = 5 * time.Second
+
+type postgresTx interface {
+	ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
+	Commit() error
+	Rollback() error
 }
 
-func NewPostgresSinkFromConfig(cfg config.SinkConfig) (Sink, error) {
-	dsn, err := requireStringParam(cfg, "dsn")
+type postgresExecer interface {
+	ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
+}
+
+type postgresDB interface {
+	PingContext(ctx context.Context) error
+	BeginTx(ctx context.Context, opts *sql.TxOptions) (postgresTx, error)
+	ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
+	Close() error
+}
+
+type sqlDBWrapper struct {
+	db *sql.DB
+}
+
+func (w *sqlDBWrapper) PingContext(ctx context.Context) error {
+	return w.db.PingContext(ctx)
+}
+
+func (w *sqlDBWrapper) BeginTx(ctx context.Context, opts *sql.TxOptions) (postgresTx, error) {
+	tx, err := w.db.BeginTx(ctx, opts)
 	if err != nil {
 		return nil, err
 	}
-	return &PostgresSink{name: cfg.Name, dsn: dsn}, nil
+	return &sqlTxWrapper{tx: tx}, nil
+}
+
+func (w *sqlDBWrapper) ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error) {
+	return w.db.ExecContext(ctx, query, args...)
+}
+
+func (w *sqlDBWrapper) Close() error {
+	return w.db.Close()
+}
+
+type sqlTxWrapper struct {
+	tx *sql.Tx
+}
+
+func (w *sqlTxWrapper) ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error) {
+	return w.tx.ExecContext(ctx, query, args...)
+}
+
+func (w *sqlTxWrapper) Commit() error {
+	return w.tx.Commit()
+}
+
+func (w *sqlTxWrapper) Rollback() error {
+	return w.tx.Rollback()
+}
+
+var openPostgresDB = func(dsn string) (postgresDB, error) {
+	db, err := sql.Open("postgres", dsn)
+	if err != nil {
+		return nil, err
+	}
+	return &sqlDBWrapper{db: db}, nil
+}
+
+type PostgresSink struct {
+	name        string
+	db          postgresDB
+	schema      postgresSchemaCompiled
+	pruneWindow time.Duration
+}
+
+func NewPostgresSinkFromConfig(cfg config.SinkConfig, schemaDef PostgresSchema) (Sink, error) {
+	uri, err := requireStringParam(cfg, "uri")
+	if err != nil {
+		return nil, err
+	}
+	username, err := requireStringParam(cfg, "username")
+	if err != nil {
+		return nil, err
+	}
+	password, err := requireStringParam(cfg, "password")
+	if err != nil {
+		return nil, err
+	}
+	pruneWindow, err := parsePostgresPruneWindow(cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	schema, err := compilePostgresSchema(schemaDef)
+	if err != nil {
+		return nil, fmt.Errorf("postgres sink %q: compile schema: %w", cfg.Name, err)
+	}
+
+	dsn, err := buildPostgresDSN(uri, username, password)
+	if err != nil {
+		return nil, fmt.Errorf("postgres sink %q: build dsn: %w", cfg.Name, err)
+	}
+
+	db, err := openPostgresDB(dsn)
+	if err != nil {
+		return nil, fmt.Errorf("postgres sink %q: open db: %w", cfg.Name, err)
+	}
+
+	s := &PostgresSink{name: cfg.Name, db: db, schema: schema, pruneWindow: pruneWindow}
+	if err := s.initialize(); err != nil {
+		_ = db.Close()
+		return nil, err
+	}
+
+	return s, nil
 }
 
 func (p *PostgresSink) Name() string { return p.name }
 
 func (p *PostgresSink) Consume(ctx context.Context, e event.Event) error {
-	_ = ctx
-
 	// Boundary validation: if something upstream violated invariants,
-	// surface it loudly rather than printing partial nonsense.
+	// surface it loudly rather than writing corrupt rows.
 	if err := e.Validate(); err != nil {
 		return fmt.Errorf("postgres sink: invalid event: %w", err)
 	}
 
-	// TODO implement Postgres transaction
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+
+	writes, err := p.schema.mapEvent(ctx, e)
+	if err != nil {
+		return fmt.Errorf("postgres sink: map event: %w", err)
+	}
+	if len(writes) == 0 {
+		return nil
+	}
+
+	tx, err := p.db.BeginTx(ctx, nil)
+	if err != nil {
+		return fmt.Errorf("postgres sink: begin tx: %w", err)
+	}
+
+	committed := false
+	defer func() {
+		if !committed {
+			_ = tx.Rollback()
+		}
+	}()
+
+	for _, w := range writes {
+		tbl, err := p.schema.validateWrite(w)
+		if err != nil {
+			return fmt.Errorf("postgres sink: %w", err)
+		}
+
+		query, args, err := buildInsertSQL(tbl, w)
+		if err != nil {
+			return fmt.Errorf("postgres sink: build insert for table %q: %w", tbl.name, err)
+		}
+		if _, err := tx.ExecContext(ctx, query, args...); err != nil {
+			return fmt.Errorf("postgres sink: insert into %q: %w", tbl.name, err)
+		}
+	}
+	if p.pruneWindow > 0 {
+		cutoff := time.Now().UTC().Add(-p.pruneWindow)
+		for _, tableName := range p.schema.tableOrder {
+			tbl := p.schema.tables[tableName]
+			if _, err := execPruneOlderThan(ctx, tx, tbl, cutoff); err != nil {
+				return fmt.Errorf("postgres sink: %w", err)
+			}
+		}
+	}
+
+	if err := tx.Commit(); err != nil {
+		return fmt.Errorf("postgres sink: commit tx: %w", err)
+	}
+	committed = true
+
 	return nil
 }
+
+func (p *PostgresSink) PruneKeepLatest(ctx context.Context, table string, keep int) (int64, error) {
+	if keep < 0 {
+		return 0, fmt.Errorf("postgres sink: keep must be >= 0")
+	}
+	tbl, err := p.lookupTable(table)
+	if err != nil {
+		return 0, err
+	}
+
+	query := fmt.Sprintf(
+		`DELETE FROM %s WHERE ctid IN (
+	SELECT ctid FROM %s
+	ORDER BY %s DESC
+	OFFSET $1
+)`,
+		quotePostgresIdent(tbl.name),
+		quotePostgresIdent(tbl.name),
+		quotePostgresIdent(tbl.pruneColumn),
+	)
+
+	res, err := p.db.ExecContext(ctx, query, keep)
+	if err != nil {
+		return 0, fmt.Errorf("postgres sink: prune keep latest table %q: %w", tbl.name, err)
+	}
+	rows, err := res.RowsAffected()
+	if err != nil {
+		return 0, fmt.Errorf("postgres sink: prune keep latest table %q rows affected: %w", tbl.name, err)
+	}
+	return rows, nil
+}
+
+func (p *PostgresSink) PruneOlderThan(ctx context.Context, table string, cutoff time.Time) (int64, error) {
+	tbl, err := p.lookupTable(table)
+	if err != nil {
+		return 0, err
+	}
+
+	rows, err := execPruneOlderThan(ctx, p.db, tbl, cutoff)
+	if err != nil {
+		return 0, fmt.Errorf("postgres sink: %w", err)
+	}
+	return rows, nil
+}
+
+func (p *PostgresSink) PruneAllKeepLatest(ctx context.Context, keep int) (map[string]int64, error) {
+	counts := make(map[string]int64, len(p.schema.tableOrder))
+	for _, table := range p.schema.tableOrder {
+		n, err := p.PruneKeepLatest(ctx, table, keep)
+		if err != nil {
+			return counts, err
+		}
+		counts[table] = n
+	}
+	return counts, nil
+}
+
+func (p *PostgresSink) PruneAllOlderThan(ctx context.Context, cutoff time.Time) (map[string]int64, error) {
+	counts := make(map[string]int64, len(p.schema.tableOrder))
+	for _, table := range p.schema.tableOrder {
+		n, err := p.PruneOlderThan(ctx, table, cutoff)
+		if err != nil {
+			return counts, err
+		}
+		counts[table] = n
+	}
+	return counts, nil
+}
+
+func (p *PostgresSink) initialize() error {
+	ctx, cancel := context.WithTimeout(context.Background(), postgresInitTimeout)
+	defer cancel()
+
+	if err := p.db.PingContext(ctx); err != nil {
+		return fmt.Errorf("postgres sink %q: ping db: %w", p.name, err)
+	}
+
+	for _, tableName := range p.schema.tableOrder {
+		tbl := p.schema.tables[tableName]
+
+		createTableSQL := buildCreateTableSQL(tbl)
+		if _, err := p.db.ExecContext(ctx, createTableSQL); err != nil {
+			return fmt.Errorf("postgres sink %q: ensure table %q: %w", p.name, tbl.name, err)
+		}
+
+		for _, idx := range tbl.indexes {
+			createIndexSQL := buildCreateIndexSQL(tbl.name, idx)
+			if _, err := p.db.ExecContext(ctx, createIndexSQL); err != nil {
+				return fmt.Errorf("postgres sink %q: ensure index %q on %q: %w", p.name, idx.Name, tbl.name, err)
+			}
+		}
+	}
+
+	return nil
+}
+
+func (p *PostgresSink) lookupTable(table string) (postgresTableCompiled, error) {
+	table = strings.TrimSpace(table)
+	if table == "" {
+		return postgresTableCompiled{}, fmt.Errorf("postgres sink: table cannot be empty")
+	}
+	tbl, ok := p.schema.tables[table]
+	if !ok {
+		return postgresTableCompiled{}, fmt.Errorf("postgres sink: unknown table %q", table)
+	}
+	return tbl, nil
+}
+
+func buildPostgresDSN(uri, username, password string) (string, error) {
+	u, err := url.Parse(strings.TrimSpace(uri))
+	if err != nil {
+		return "", fmt.Errorf("invalid uri: %w", err)
+	}
+	if u.Scheme == "" {
+		return "", fmt.Errorf("invalid uri: missing scheme")
+	}
+	if u.Host == "" {
+		return "", fmt.Errorf("invalid uri: missing host")
+	}
+	u.User = url.UserPassword(username, password)
+	return u.String(), nil
+}
+
+func parsePostgresPruneWindow(cfg config.SinkConfig) (time.Duration, error) {
+	raw, ok := cfg.Params["prune"]
+	if !ok || raw == nil {
+		return 0, nil
+	}
+
+	s, ok := raw.(string)
+	if !ok {
+		return 0, fmt.Errorf("sink %q: params.prune must be a string duration (e.g. 72h, 3d, 2w)", cfg.Name)
+	}
+
+	d, err := parsePostgresPruneDuration(s)
+	if err != nil {
+		return 0, fmt.Errorf("sink %q: params.prune %q is invalid: %w", cfg.Name, s, err)
+	}
+	return d, nil
+}
+
+func parsePostgresPruneDuration(raw string) (time.Duration, error) {
+	s := strings.TrimSpace(raw)
+	if s == "" {
+		return 0, fmt.Errorf("must not be empty")
+	}
+
+	lower := strings.ToLower(s)
+	if strings.HasSuffix(lower, "d") || strings.HasSuffix(lower, "w") {
+		unit := lower[len(lower)-1]
+		n, err := strconv.Atoi(strings.TrimSpace(lower[:len(lower)-1]))
+		if err != nil {
+			return 0, fmt.Errorf("must use a positive integer before %q", string(unit))
+		}
+		if n <= 0 {
+			return 0, fmt.Errorf("must be > 0")
+		}
+		if unit == 'd' {
+			return time.Duration(n) * 24 * time.Hour, nil
+		}
+		return time.Duration(n) * 7 * 24 * time.Hour, nil
+	}
+
+	d, err := time.ParseDuration(s)
+	if err != nil {
+		return 0, fmt.Errorf("must be a Go duration or use d/w suffixes")
+	}
+	if d <= 0 {
+		return 0, fmt.Errorf("must be > 0")
+	}
+	return d, nil
+}
+
+func buildPruneOlderThanSQL(tbl postgresTableCompiled) string {
+	return fmt.Sprintf(
+		`DELETE FROM %s WHERE %s < $1`,
+		quotePostgresIdent(tbl.name),
+		quotePostgresIdent(tbl.pruneColumn),
+	)
+}
+
+func execPruneOlderThan(ctx context.Context, execer postgresExecer, tbl postgresTableCompiled, cutoff time.Time) (int64, error) {
+	query := buildPruneOlderThanSQL(tbl)
+	res, err := execer.ExecContext(ctx, query, cutoff)
+	if err != nil {
+		return 0, fmt.Errorf("prune older than table %q: %w", tbl.name, err)
+	}
+	rows, err := res.RowsAffected()
+	if err != nil {
+		return 0, fmt.Errorf("prune older than table %q rows affected: %w", tbl.name, err)
+	}
+	return rows, nil
+}
+
+func buildCreateTableSQL(tbl postgresTableCompiled) string {
+	defs := make([]string, 0, len(tbl.columnOrder)+1)
+	for _, colName := range tbl.columnOrder {
+		col := tbl.columns[colName]
+		def := fmt.Sprintf("%s %s", quotePostgresIdent(col.Name), col.Type)
+		if !col.Nullable {
+			def += " NOT NULL"
+		}
+		defs = append(defs, def)
+	}
+	if len(tbl.primaryKey) > 0 {
+		defs = append(defs, fmt.Sprintf("PRIMARY KEY (%s)", joinQuotedIdents(tbl.primaryKey)))
+	}
+
+	return fmt.Sprintf(
+		"CREATE TABLE IF NOT EXISTS %s (%s)",
+		quotePostgresIdent(tbl.name),
+		strings.Join(defs, ", "),
+	)
+}
+
+func buildCreateIndexSQL(tableName string, idx PostgresIndex) string {
+	unique := ""
+	if idx.Unique {
+		unique = "UNIQUE "
+	}
+
+	return fmt.Sprintf(
+		"CREATE %sINDEX IF NOT EXISTS %s ON %s (%s)",
+		unique,
+		quotePostgresIdent(idx.Name),
+		quotePostgresIdent(tableName),
+		joinQuotedIdents(idx.Columns),
+	)
+}
+
+func buildInsertSQL(tbl postgresTableCompiled, w PostgresWrite) (string, []any, error) {
+	cols := make([]string, 0, len(tbl.columnOrder))
+	args := make([]any, 0, len(tbl.columnOrder))
+	placeholders := make([]string, 0, len(tbl.columnOrder))
+
+	for i, colName := range tbl.columnOrder {
+		v, ok := w.Values[colName]
+		if !ok {
+			return "", nil, fmt.Errorf("missing value for column %q", colName)
+		}
+		cols = append(cols, quotePostgresIdent(colName))
+		args = append(args, v)
+		placeholders = append(placeholders, "$"+strconv.Itoa(i+1))
+	}
+
+	q := fmt.Sprintf(
+		"INSERT INTO %s (%s) VALUES (%s)",
+		quotePostgresIdent(tbl.name),
+		strings.Join(cols, ", "),
+		strings.Join(placeholders, ", "),
+	)
+	return q, args, nil
+}
+
+func joinQuotedIdents(idents []string) string {
+	quoted := make([]string, 0, len(idents))
+	for _, s := range idents {
+		quoted = append(quoted, quotePostgresIdent(s))
+	}
+	return strings.Join(quoted, ", ")
+}
+
+func quotePostgresIdent(s string) string {
+	return `"` + strings.ReplaceAll(s, `"`, `""`) + `"`
+}

sinks/postgres_schema.go

@@ -0,0 +1,239 @@
+package sinks
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+// PostgresMapFunc maps one event into zero or more table writes.
+//
+// Returning zero writes means "this event is not mapped for this sink" and is
+// treated as a non-error no-op.
+type PostgresMapFunc func(ctx context.Context, e event.Event) ([]PostgresWrite, error)
+
+// PostgresSchema describes the downstream-provided relational model and mapper
+// for one configured postgres sink.
+type PostgresSchema struct {
+	Tables   []PostgresTable
+	MapEvent PostgresMapFunc
+}
+
+type PostgresWrite struct {
+	Table  string
+	Values map[string]any
+}
+
+type PostgresTable struct {
+	Name        string
+	Columns     []PostgresColumn
+	PrimaryKey  []string
+	PruneColumn string
+	Indexes     []PostgresIndex
+}
+
+type PostgresColumn struct {
+	Name     string
+	Type     string
+	Nullable bool
+}
+
+type PostgresIndex struct {
+	Name    string
+	Columns []string
+	Unique  bool
+}
+
+// PostgresPruner is an optional interface exposed by PostgresSink so downstream
+// applications can call retention helpers via type assertion.
+type PostgresPruner interface {
+	PruneKeepLatest(ctx context.Context, table string, keep int) (int64, error)
+	PruneOlderThan(ctx context.Context, table string, cutoff time.Time) (int64, error)
+	PruneAllKeepLatest(ctx context.Context, keep int) (map[string]int64, error)
+	PruneAllOlderThan(ctx context.Context, cutoff time.Time) (map[string]int64, error)
+}
+
+type postgresSchemaCompiled struct {
+	tableOrder []string
+	tables     map[string]postgresTableCompiled
+	mapEvent   PostgresMapFunc
+}
+
+type postgresTableCompiled struct {
+	name        string
+	columns     map[string]PostgresColumn
+	columnOrder []string
+	primaryKey  []string
+	pruneColumn string
+	indexes     []PostgresIndex
+}
+
+func compilePostgresSchema(schema PostgresSchema) (postgresSchemaCompiled, error) {
+	if schema.MapEvent == nil {
+		return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: map function is required")
+	}
+	if len(schema.Tables) == 0 {
+		return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: at least one table is required")
+	}
+
+	compiled := postgresSchemaCompiled{
+		tableOrder: make([]string, 0, len(schema.Tables)),
+		tables:     make(map[string]postgresTableCompiled, len(schema.Tables)),
+		mapEvent:   schema.MapEvent,
+	}
+
+	seenTables := map[string]bool{}
+	seenIndexes := map[string]bool{}
+
+	for i, tbl := range schema.Tables {
+		tableName := strings.TrimSpace(tbl.Name)
+		if tableName == "" {
+			return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: tables[%d].name is required", i)
+		}
+		if seenTables[tableName] {
+			return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: duplicate table name %q", tableName)
+		}
+		seenTables[tableName] = true
+
+		if len(tbl.Columns) == 0 {
+			return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: table %q must define at least one column", tableName)
+		}
+
+		colOrder := make([]string, 0, len(tbl.Columns))
+		colMap := make(map[string]PostgresColumn, len(tbl.Columns))
+		for j, col := range tbl.Columns {
+			colName := strings.TrimSpace(col.Name)
+			if colName == "" {
+				return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: table %q columns[%d].name is required", tableName, j)
+			}
+			if _, exists := colMap[colName]; exists {
+				return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: table %q duplicate column %q", tableName, colName)
+			}
+			if strings.TrimSpace(col.Type) == "" {
+				return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: table %q column %q type is required", tableName, colName)
+			}
+			colOrder = append(colOrder, colName)
+			colMap[colName] = PostgresColumn{
+				Name:     colName,
+				Type:     strings.TrimSpace(col.Type),
+				Nullable: col.Nullable,
+			}
+		}
+
+		pk, err := validatePostgresColumnSet(tableName, "primary key", tbl.PrimaryKey, colMap)
+		if err != nil {
+			return postgresSchemaCompiled{}, err
+		}
+
+		pruneCol := strings.TrimSpace(tbl.PruneColumn)
+		if pruneCol == "" {
+			return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: table %q prune column is required", tableName)
+		}
+		if _, ok := colMap[pruneCol]; !ok {
+			return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: table %q prune column %q not found in columns", tableName, pruneCol)
+		}
+
+		indexes := make([]PostgresIndex, 0, len(tbl.Indexes))
+		for j, idx := range tbl.Indexes {
+			idxName := strings.TrimSpace(idx.Name)
+			if idxName == "" {
+				return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: table %q indexes[%d].name is required", tableName, j)
+			}
+			if len(idx.Columns) == 0 {
+				return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: table %q index %q must include at least one column", tableName, idxName)
+			}
+			if seenIndexes[idxName] {
+				return postgresSchemaCompiled{}, fmt.Errorf("postgres schema: duplicate index name %q", idxName)
+			}
+			seenIndexes[idxName] = true
+
+			idxCols, err := validatePostgresColumnSet(tableName, fmt.Sprintf("index %q columns", idxName), idx.Columns, colMap)
+			if err != nil {
+				return postgresSchemaCompiled{}, err
+			}
+
+			indexes = append(indexes, PostgresIndex{
+				Name:    idxName,
+				Columns: idxCols,
+				Unique:  idx.Unique,
+			})
+		}
+
+		compiled.tableOrder = append(compiled.tableOrder, tableName)
+		compiled.tables[tableName] = postgresTableCompiled{
+			name:        tableName,
+			columns:     colMap,
+			columnOrder: colOrder,
+			primaryKey:  pk,
+			pruneColumn: pruneCol,
+			indexes:     indexes,
+		}
+	}
+
+	return compiled, nil
+}
+
+func validatePostgresColumnSet(tableName, label string, cols []string, colMap map[string]PostgresColumn) ([]string, error) {
+	if len(cols) == 0 {
+		return nil, nil
+	}
+	out := make([]string, 0, len(cols))
+	seen := map[string]bool{}
+	for _, c := range cols {
+		name := strings.TrimSpace(c)
+		if name == "" {
+			return nil, fmt.Errorf("postgres schema: table %q %s contains empty column name", tableName, label)
+		}
+		if seen[name] {
+			return nil, fmt.Errorf("postgres schema: table %q %s contains duplicate column %q", tableName, label, name)
+		}
+		if _, ok := colMap[name]; !ok {
+			return nil, fmt.Errorf("postgres schema: table %q %s references unknown column %q", tableName, label, name)
+		}
+		seen[name] = true
+		out = append(out, name)
+	}
+	return out, nil
+}
+
+func (s postgresSchemaCompiled) validateWrite(w PostgresWrite) (postgresTableCompiled, error) {
+	tableName := strings.TrimSpace(w.Table)
+	if tableName == "" {
+		return postgresTableCompiled{}, fmt.Errorf("write table is required")
+	}
+	t, ok := s.tables[tableName]
+	if !ok {
+		return postgresTableCompiled{}, fmt.Errorf("table %q is not defined in postgres schema", tableName)
+	}
+
+	if len(w.Values) == 0 {
+		return postgresTableCompiled{}, fmt.Errorf("write for table %q must include values", tableName)
+	}
+
+	for k := range w.Values {
+		if _, ok := t.columns[k]; !ok {
+			return postgresTableCompiled{}, fmt.Errorf("write for table %q includes unknown column %q", tableName, k)
+		}
+	}
+
+	if len(w.Values) != len(t.columnOrder) {
+		return postgresTableCompiled{}, fmt.Errorf("write for table %q must include all declared columns", tableName)
+	}
+
+	for _, col := range t.columnOrder {
+		v, ok := w.Values[col]
+		if !ok {
+			return postgresTableCompiled{}, fmt.Errorf("write for table %q is missing column %q", tableName, col)
+		}
+		if v == nil {
+			if c := t.columns[col]; !c.Nullable {
+				return postgresTableCompiled{}, fmt.Errorf("write for table %q has nil value for non-null column %q", tableName, col)
+			}
+		}
+	}
+
+	return t, nil
+}

sinks/postgres_test.go

@@ -0,0 +1,741 @@
+package sinks
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"net/url"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+type fakeResult struct {
+	rows int64
+}
+
+func (r fakeResult) LastInsertId() (int64, error) { return 0, errors.New("unsupported") }
+func (r fakeResult) RowsAffected() (int64, error) { return r.rows, nil }
+
+type execCall struct {
+	query string
+	args  []any
+}
+
+type fakeTx struct {
+	execCalls     []execCall
+	execErr       error
+	execErrOnCall int
+	execRows      int64
+	commitErr     error
+	rollbackErr   error
+	commitCalls   int
+	rollbackCalls int
+}
+
+func (t *fakeTx) ExecContext(_ context.Context, query string, args ...any) (sql.Result, error) {
+	t.execCalls = append(t.execCalls, execCall{query: query, args: append([]any(nil), args...)})
+	if t.execErr != nil && t.execErrOnCall == len(t.execCalls) {
+		return nil, t.execErr
+	}
+	return fakeResult{rows: t.execRows}, nil
+}
+
+func (t *fakeTx) Commit() error {
+	t.commitCalls++
+	return t.commitErr
+}
+
+func (t *fakeTx) Rollback() error {
+	t.rollbackCalls++
+	return t.rollbackErr
+}
+
+type fakeDB struct {
+	pingErr       error
+	beginErr      error
+	execErr       error
+	execErrOnCall int
+	execRows      int64
+	pingCalls     int
+	beginCalls    int
+	execCalls     []execCall
+	closeCalls    int
+	tx            *fakeTx
+}
+
+func (d *fakeDB) PingContext(_ context.Context) error {
+	d.pingCalls++
+	return d.pingErr
+}
+
+func (d *fakeDB) BeginTx(_ context.Context, _ *sql.TxOptions) (postgresTx, error) {
+	d.beginCalls++
+	if d.beginErr != nil {
+		return nil, d.beginErr
+	}
+	if d.tx == nil {
+		d.tx = &fakeTx{}
+	}
+	return d.tx, nil
+}
+
+func (d *fakeDB) ExecContext(_ context.Context, query string, args ...any) (sql.Result, error) {
+	d.execCalls = append(d.execCalls, execCall{query: query, args: append([]any(nil), args...)})
+	if d.execErr != nil && d.execErrOnCall == len(d.execCalls) {
+		return nil, d.execErr
+	}
+	return fakeResult{rows: d.execRows}, nil
+}
+
+func (d *fakeDB) Close() error {
+	d.closeCalls++
+	return nil
+}
+
+func withPostgresTestState(t *testing.T) {
+	t.Helper()
+
+	oldOpen := openPostgresDB
+	t.Cleanup(func() {
+		openPostgresDB = oldOpen
+	})
+}
+
+func validTestEvent() event.Event {
+	now := time.Now().UTC()
+	return event.Event{
+		ID:        "evt-1",
+		Kind:      event.Kind("observation"),
+		Source:    "source-1",
+		EmittedAt: now,
+		Payload: map[string]any{
+			"x": 1,
+		},
+	}
+}
+
+func schemaOneTable(mapFn PostgresMapFunc) PostgresSchema {
+	return PostgresSchema{
+		Tables: []PostgresTable{
+			{
+				Name: "events",
+				Columns: []PostgresColumn{
+					{Name: "event_id", Type: "TEXT", Nullable: false},
+					{Name: "emitted_at", Type: "TIMESTAMPTZ", Nullable: false},
+					{Name: "payload_json", Type: "JSONB", Nullable: false},
+				},
+				PrimaryKey:  []string{"event_id"},
+				PruneColumn: "emitted_at",
+				Indexes: []PostgresIndex{
+					{Name: "idx_events_emitted_at", Columns: []string{"emitted_at"}},
+				},
+			},
+		},
+		MapEvent: mapFn,
+	}
+}
+
+func schemaTwoTables(mapFn PostgresMapFunc) PostgresSchema {
+	return PostgresSchema{
+		Tables: []PostgresTable{
+			{
+				Name: "events",
+				Columns: []PostgresColumn{
+					{Name: "event_id", Type: "TEXT", Nullable: false},
+					{Name: "emitted_at", Type: "TIMESTAMPTZ", Nullable: false},
+				},
+				PrimaryKey:  []string{"event_id"},
+				PruneColumn: "emitted_at",
+			},
+			{
+				Name: "event_payloads",
+				Columns: []PostgresColumn{
+					{Name: "event_id", Type: "TEXT", Nullable: false},
+					{Name: "payload_json", Type: "JSONB", Nullable: false},
+					{Name: "emitted_at", Type: "TIMESTAMPTZ", Nullable: false},
+				},
+				PrimaryKey:  []string{"event_id"},
+				PruneColumn: "emitted_at",
+			},
+		},
+		MapEvent: mapFn,
+	}
+}
+
+func mustCompileSchema(t *testing.T, s PostgresSchema) postgresSchemaCompiled {
+	t.Helper()
+	compiled, err := compilePostgresSchema(s)
+	if err != nil {
+		t.Fatalf("compile schema: %v", err)
+	}
+	return compiled
+}
+
+func TestCompilePostgresSchemaRejectsInvalidSchema(t *testing.T) {
+	_, err := compilePostgresSchema(PostgresSchema{
+		Tables: []PostgresTable{
+			{
+				Name: "events",
+				Columns: []PostgresColumn{
+					{Name: "id", Type: "TEXT", Nullable: false},
+				},
+				PruneColumn: "missing_col",
+			},
+		},
+		MapEvent: func(_ context.Context, _ event.Event) ([]PostgresWrite, error) { return nil, nil },
+	})
+	if err == nil {
+		t.Fatalf("expected invalid schema error")
+	}
+	if !strings.Contains(err.Error(), "prune column") {
+		t.Fatalf("unexpected schema validation error: %v", err)
+	}
+
+	_, err = compilePostgresSchema(PostgresSchema{
+		Tables: []PostgresTable{
+			{
+				Name: "events",
+				Columns: []PostgresColumn{
+					{Name: "id", Type: "TEXT", Nullable: false},
+					{Name: "emitted_at", Type: "TIMESTAMPTZ", Nullable: false},
+				},
+				PruneColumn: "emitted_at",
+				Indexes: []PostgresIndex{
+					{Name: "idx_events_empty", Columns: nil},
+				},
+			},
+		},
+		MapEvent: func(_ context.Context, _ event.Event) ([]PostgresWrite, error) { return nil, nil },
+	})
+	if err == nil {
+		t.Fatalf("expected invalid index schema error")
+	}
+	if !strings.Contains(err.Error(), "at least one column") {
+		t.Fatalf("unexpected index validation error: %v", err)
+	}
+}
+
+func TestPostgresFactoryBuildsMultipleSinksWithSameSchema(t *testing.T) {
+	withPostgresTestState(t)
+
+	dbs := []*fakeDB{{}, {}}
+	var gotDSNs []string
+	openPostgresDB = func(dsn string) (postgresDB, error) {
+		gotDSNs = append(gotDSNs, dsn)
+		db := dbs[len(gotDSNs)-1]
+		return db, nil
+	}
+
+	factory := PostgresFactory(schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) {
+		return nil, nil
+	}))
+
+	for _, name := range []string{"pg_a", "pg_b"} {
+		sink, err := factory(config.SinkConfig{
+			Name:   name,
+			Driver: "postgres",
+			Params: map[string]any{
+				"uri":      "postgres://localhost/db",
+				"username": "user",
+				"password": "pass",
+			},
+		})
+		if err != nil {
+			t.Fatalf("factory(%q) error = %v", name, err)
+		}
+		if sink == nil {
+			t.Fatalf("factory(%q) returned nil sink", name)
+		}
+	}
+
+	if len(gotDSNs) != 2 {
+		t.Fatalf("len(gotDSNs) = %d, want 2", len(gotDSNs))
+	}
+	for i, db := range dbs {
+		if db.pingCalls != 1 {
+			t.Fatalf("db[%d] pingCalls = %d, want 1", i, db.pingCalls)
+		}
+	}
+}
+
+func TestNewPostgresSinkFromConfigMissingParams(t *testing.T) {
+	withPostgresTestState(t)
+
+	tests := []struct {
+		name   string
+		params map[string]any
+		want   string
+	}{
+		{name: "missing uri", params: map[string]any{"username": "u", "password": "p"}, want: "params.uri"},
+		{name: "missing username", params: map[string]any{"uri": "postgres://localhost/db", "password": "p"}, want: "params.username"},
+		{name: "missing password", params: map[string]any{"uri": "postgres://localhost/db", "username": "u"}, want: "params.password"},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err := NewPostgresSinkFromConfig(config.SinkConfig{
+				Name:   "pg",
+				Driver: "postgres",
+				Params: tc.params,
+			}, schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) { return nil, nil }))
+			if err == nil {
+				t.Fatalf("expected error")
+			}
+			if !strings.Contains(err.Error(), tc.want) {
+				t.Fatalf("expected %q in error, got: %v", tc.want, err)
+			}
+		})
+	}
+}
+
+func TestNewPostgresSinkFromConfigRejectsInvalidSchema(t *testing.T) {
+	withPostgresTestState(t)
+
+	_, err := NewPostgresSinkFromConfig(config.SinkConfig{
+		Name:   "pg",
+		Driver: "postgres",
+		Params: map[string]any{
+			"uri":      "postgres://localhost/db",
+			"username": "user",
+			"password": "pass",
+		},
+	}, PostgresSchema{
+		Tables: []PostgresTable{
+			{
+				Name: "events",
+				Columns: []PostgresColumn{
+					{Name: "id", Type: "TEXT", Nullable: false},
+				},
+				PruneColumn: "missing_col",
+			},
+		},
+		MapEvent: func(_ context.Context, _ event.Event) ([]PostgresWrite, error) { return nil, nil },
+	})
+	if err == nil {
+		t.Fatalf("expected invalid schema error")
+	}
+	if !strings.Contains(err.Error(), "compile schema") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestNewPostgresSinkFromConfigEagerInit(t *testing.T) {
+	withPostgresTestState(t)
+
+	db := &fakeDB{}
+	var gotDSN string
+	openPostgresDB = func(dsn string) (postgresDB, error) {
+		gotDSN = dsn
+		return db, nil
+	}
+
+	s, err := NewPostgresSinkFromConfig(config.SinkConfig{
+		Name:   "pg",
+		Driver: "postgres",
+		Params: map[string]any{
+			"uri":      "postgres://db.example.local:5432/feedkit?sslmode=disable",
+			"username": "app_user",
+			"password": "app_pass",
+		},
+	}, schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) { return nil, nil }))
+	if err != nil {
+		t.Fatalf("new postgres sink: %v", err)
+	}
+	if s == nil {
+		t.Fatalf("expected sink")
+	}
+
+	if db.pingCalls != 1 {
+		t.Fatalf("expected one ping, got %d", db.pingCalls)
+	}
+	if len(db.execCalls) != 2 {
+		t.Fatalf("expected 2 init exec calls (table + index), got %d", len(db.execCalls))
+	}
+	if !strings.Contains(db.execCalls[0].query, `CREATE TABLE IF NOT EXISTS "events"`) {
+		t.Fatalf("unexpected create table query: %s", db.execCalls[0].query)
+	}
+	if !strings.Contains(db.execCalls[1].query, `CREATE INDEX IF NOT EXISTS "idx_events_emitted_at"`) {
+		t.Fatalf("unexpected create index query: %s", db.execCalls[1].query)
+	}
+
+	u, err := url.Parse(gotDSN)
+	if err != nil {
+		t.Fatalf("parse dsn: %v", err)
+	}
+	if u.User == nil || u.User.Username() != "app_user" {
+		t.Fatalf("dsn missing username: %q", gotDSN)
+	}
+	pass, ok := u.User.Password()
+	if !ok || pass != "app_pass" {
+		t.Fatalf("dsn missing password: %q", gotDSN)
+	}
+}
+
+func TestNewPostgresSinkFromConfigInitFailureClosesDB(t *testing.T) {
+	withPostgresTestState(t)
+
+	db := &fakeDB{execErrOnCall: 1, execErr: errors.New("ddl failed")}
+	openPostgresDB = func(_ string) (postgresDB, error) {
+		return db, nil
+	}
+
+	_, err := NewPostgresSinkFromConfig(config.SinkConfig{
+		Name:   "pg",
+		Driver: "postgres",
+		Params: map[string]any{
+			"uri":      "postgres://localhost/db",
+			"username": "user",
+			"password": "pass",
+		},
+	}, schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) { return nil, nil }))
+	if err == nil {
+		t.Fatalf("expected init error")
+	}
+	if db.closeCalls != 1 {
+		t.Fatalf("expected db close on init failure")
+	}
+}
+
+func TestNewPostgresSinkFromConfigPruneParamAccepted(t *testing.T) {
+	tests := []struct {
+		name string
+		in   string
+		want time.Duration
+	}{
+		{name: "go duration", in: "72h", want: 72 * time.Hour},
+		{name: "days suffix", in: "3d", want: 72 * time.Hour},
+		{name: "weeks suffix", in: "2w", want: 14 * 24 * time.Hour},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			withPostgresTestState(t)
+
+			openPostgresDB = func(_ string) (postgresDB, error) {
+				return &fakeDB{}, nil
+			}
+
+			s, err := NewPostgresSinkFromConfig(config.SinkConfig{
+				Name:   "pg",
+				Driver: "postgres",
+				Params: map[string]any{
+					"uri":      "postgres://localhost/db",
+					"username": "user",
+					"password": "pass",
+					"prune":    tc.in,
+				},
+			}, schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) { return nil, nil }))
+			if err != nil {
+				t.Fatalf("new postgres sink: %v", err)
+			}
+
+			pg, ok := s.(*PostgresSink)
+			if !ok {
+				t.Fatalf("expected *PostgresSink, got %T", s)
+			}
+			if pg.pruneWindow != tc.want {
+				t.Fatalf("prune window = %s, want %s", pg.pruneWindow, tc.want)
+			}
+		})
+	}
+}
+
+func TestNewPostgresSinkFromConfigPruneParamRejected(t *testing.T) {
+	withPostgresTestState(t)
+
+	tests := []struct {
+		name string
+		in   any
+	}{
+		{name: "empty", in: ""},
+		{name: "zero", in: "0"},
+		{name: "negative", in: "-1h"},
+		{name: "malformed", in: "abc"},
+		{name: "fractional day", in: "1.5d"},
+		{name: "wrong type", in: 5},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err := NewPostgresSinkFromConfig(config.SinkConfig{
+				Name:   "pg",
+				Driver: "postgres",
+				Params: map[string]any{
+					"uri":      "postgres://localhost/db",
+					"username": "user",
+					"password": "pass",
+					"prune":    tc.in,
+				},
+			}, schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) { return nil, nil }))
+			if err == nil {
+				t.Fatalf("expected error")
+			}
+			if !strings.Contains(err.Error(), "params.prune") {
+				t.Fatalf("expected params.prune error, got %v", err)
+			}
+		})
+	}
+}
+
+func TestPostgresSinkConsumeInvalidEvent(t *testing.T) {
+	db := &fakeDB{}
+	called := 0
+	sink := &PostgresSink{
+		name: "pg",
+		db:   db,
+		schema: mustCompileSchema(t, schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) {
+			called++
+			return nil, nil
+		})),
+	}
+
+	err := sink.Consume(context.Background(), event.Event{})
+	if err == nil {
+		t.Fatalf("expected invalid event error")
+	}
+	if !strings.Contains(err.Error(), "invalid event") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if called != 0 {
+		t.Fatalf("expected mapper not called for invalid events")
+	}
+}
+
+func TestPostgresSinkConsumeUnmappedEventIsNoOp(t *testing.T) {
+	db := &fakeDB{}
+	sink := &PostgresSink{
+		name: "pg",
+		db:   db,
+		schema: mustCompileSchema(t, schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) {
+			return nil, nil
+		})),
+	}
+
+	if err := sink.Consume(context.Background(), validTestEvent()); err != nil {
+		t.Fatalf("consume: %v", err)
+	}
+	if db.beginCalls != 0 {
+		t.Fatalf("expected no transaction for unmapped events")
+	}
+}
+
+func TestPostgresSinkConsumeOneEventWritesMultipleTablesAtomically(t *testing.T) {
+	tx := &fakeTx{}
+	db := &fakeDB{tx: tx}
+	sink := &PostgresSink{
+		name: "pg",
+		db:   db,
+		schema: mustCompileSchema(t, schemaTwoTables(func(_ context.Context, e event.Event) ([]PostgresWrite, error) {
+			return []PostgresWrite{
+				{Table: "events", Values: map[string]any{"event_id": e.ID, "emitted_at": e.EmittedAt}},
+				{Table: "event_payloads", Values: map[string]any{"event_id": e.ID, "payload_json": `{}`, "emitted_at": e.EmittedAt}},
+			}, nil
+		})),
+	}
+
+	if err := sink.Consume(context.Background(), validTestEvent()); err != nil {
+		t.Fatalf("consume: %v", err)
+	}
+	if db.beginCalls != 1 {
+		t.Fatalf("expected one transaction begin, got %d", db.beginCalls)
+	}
+	if len(tx.execCalls) != 2 {
+		t.Fatalf("expected 2 insert statements, got %d", len(tx.execCalls))
+	}
+	if tx.commitCalls != 1 {
+		t.Fatalf("expected one commit, got %d", tx.commitCalls)
+	}
+	if tx.rollbackCalls != 0 {
+		t.Fatalf("expected zero rollbacks, got %d", tx.rollbackCalls)
+	}
+}
+
+func TestPostgresSinkConsumeInsertFailureRollsBack(t *testing.T) {
+	tx := &fakeTx{execErrOnCall: 2, execErr: errors.New("duplicate key")}
+	db := &fakeDB{tx: tx}
+	sink := &PostgresSink{
+		name: "pg",
+		db:   db,
+		schema: mustCompileSchema(t, schemaTwoTables(func(_ context.Context, e event.Event) ([]PostgresWrite, error) {
+			return []PostgresWrite{
+				{Table: "events", Values: map[string]any{"event_id": e.ID, "emitted_at": e.EmittedAt}},
+				{Table: "event_payloads", Values: map[string]any{"event_id": e.ID, "payload_json": `{}`, "emitted_at": e.EmittedAt}},
+			}, nil
+		})),
+	}
+
+	err := sink.Consume(context.Background(), validTestEvent())
+	if err == nil {
+		t.Fatalf("expected insert error")
+	}
+	if !strings.Contains(err.Error(), "insert into") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if tx.commitCalls != 0 {
+		t.Fatalf("expected no commit")
+	}
+	if tx.rollbackCalls != 1 {
+		t.Fatalf("expected rollback, got %d", tx.rollbackCalls)
+	}
+}
+
+func TestPostgresSinkConsumeAutoPruneRunsInSameTransaction(t *testing.T) {
+	tx := &fakeTx{}
+	db := &fakeDB{tx: tx}
+	sink := &PostgresSink{
+		name: "pg",
+		db:   db,
+		schema: mustCompileSchema(t, schemaTwoTables(func(_ context.Context, e event.Event) ([]PostgresWrite, error) {
+			return []PostgresWrite{
+				{Table: "events", Values: map[string]any{"event_id": e.ID, "emitted_at": e.EmittedAt}},
+				{Table: "event_payloads", Values: map[string]any{"event_id": e.ID, "payload_json": `{}`, "emitted_at": e.EmittedAt}},
+			}, nil
+		})),
+		pruneWindow: 24 * time.Hour,
+	}
+
+	if err := sink.Consume(context.Background(), validTestEvent()); err != nil {
+		t.Fatalf("consume: %v", err)
+	}
+	if len(tx.execCalls) != 4 {
+		t.Fatalf("expected 4 tx statements (2 inserts + 2 prunes), got %d", len(tx.execCalls))
+	}
+	if !strings.Contains(tx.execCalls[2].query, `DELETE FROM "events"`) {
+		t.Fatalf("expected prune delete for events, got %s", tx.execCalls[2].query)
+	}
+	if !strings.Contains(tx.execCalls[3].query, `DELETE FROM "event_payloads"`) {
+		t.Fatalf("expected prune delete for event_payloads, got %s", tx.execCalls[3].query)
+	}
+	if tx.commitCalls != 1 {
+		t.Fatalf("expected one commit, got %d", tx.commitCalls)
+	}
+	if tx.rollbackCalls != 0 {
+		t.Fatalf("expected zero rollbacks, got %d", tx.rollbackCalls)
+	}
+}
+
+func TestPostgresSinkConsumeAutoPruneFailureRollsBack(t *testing.T) {
+	tx := &fakeTx{execErrOnCall: 3, execErr: errors.New("prune failed")}
+	db := &fakeDB{tx: tx}
+	sink := &PostgresSink{
+		name: "pg",
+		db:   db,
+		schema: mustCompileSchema(t, schemaTwoTables(func(_ context.Context, e event.Event) ([]PostgresWrite, error) {
+			return []PostgresWrite{
+				{Table: "events", Values: map[string]any{"event_id": e.ID, "emitted_at": e.EmittedAt}},
+				{Table: "event_payloads", Values: map[string]any{"event_id": e.ID, "payload_json": `{}`, "emitted_at": e.EmittedAt}},
+			}, nil
+		})),
+		pruneWindow: 24 * time.Hour,
+	}
+
+	err := sink.Consume(context.Background(), validTestEvent())
+	if err == nil {
+		t.Fatalf("expected prune error")
+	}
+	if !strings.Contains(err.Error(), "prune older than") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if tx.commitCalls != 0 {
+		t.Fatalf("expected no commit")
+	}
+	if tx.rollbackCalls != 1 {
+		t.Fatalf("expected rollback, got %d", tx.rollbackCalls)
+	}
+}
+
+func TestPostgresSinkPrunePerTable(t *testing.T) {
+	db := &fakeDB{execRows: 7}
+	sink := &PostgresSink{
+		name: "pg",
+		db:   db,
+		schema: mustCompileSchema(t, schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) {
+			return nil, nil
+		})),
+	}
+
+	rows, err := sink.PruneKeepLatest(context.Background(), "events", 10)
+	if err != nil {
+		t.Fatalf("prune keep latest: %v", err)
+	}
+	if rows != 7 {
+		t.Fatalf("unexpected rows affected: %d", rows)
+	}
+	if len(db.execCalls) != 1 {
+		t.Fatalf("expected one prune query")
+	}
+	if !strings.Contains(db.execCalls[0].query, `ORDER BY "emitted_at" DESC`) {
+		t.Fatalf("unexpected keep-latest query: %s", db.execCalls[0].query)
+	}
+	if len(db.execCalls[0].args) != 1 || db.execCalls[0].args[0] != 10 {
+		t.Fatalf("unexpected keep-latest args: %#v", db.execCalls[0].args)
+	}
+
+	cutoff := time.Now().UTC().Add(-24 * time.Hour)
+	rows, err = sink.PruneOlderThan(context.Background(), "events", cutoff)
+	if err != nil {
+		t.Fatalf("prune older than: %v", err)
+	}
+	if rows != 7 {
+		t.Fatalf("unexpected rows affected: %d", rows)
+	}
+	if len(db.execCalls) != 2 {
+		t.Fatalf("expected two prune queries")
+	}
+	if !strings.Contains(db.execCalls[1].query, `WHERE "emitted_at" < $1`) {
+		t.Fatalf("unexpected older-than query: %s", db.execCalls[1].query)
+	}
+}
+
+func TestPostgresSinkPruneAllTables(t *testing.T) {
+	db := &fakeDB{execRows: 3}
+	sink := &PostgresSink{
+		name: "pg",
+		db:   db,
+		schema: mustCompileSchema(t, schemaTwoTables(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) {
+			return nil, nil
+		})),
+	}
+
+	keepCounts, err := sink.PruneAllKeepLatest(context.Background(), 5)
+	if err != nil {
+		t.Fatalf("prune all keep latest: %v", err)
+	}
+	if len(keepCounts) != 2 || keepCounts["events"] != 3 || keepCounts["event_payloads"] != 3 {
+		t.Fatalf("unexpected keep counts: %#v", keepCounts)
+	}
+
+	db.execCalls = nil
+	olderCounts, err := sink.PruneAllOlderThan(context.Background(), time.Now().UTC())
+	if err != nil {
+		t.Fatalf("prune all older than: %v", err)
+	}
+	if len(olderCounts) != 2 || olderCounts["events"] != 3 || olderCounts["event_payloads"] != 3 {
+		t.Fatalf("unexpected older-than counts: %#v", olderCounts)
+	}
+	if len(db.execCalls) != 2 {
+		t.Fatalf("expected one prune call per table")
+	}
+}
+
+func TestPostgresSinkPruneErrors(t *testing.T) {
+	db := &fakeDB{}
+	sink := &PostgresSink{
+		name: "pg",
+		db:   db,
+		schema: mustCompileSchema(t, schemaOneTable(func(_ context.Context, _ event.Event) ([]PostgresWrite, error) {
+			return nil, nil
+		})),
+	}
+
+	if _, err := sink.PruneKeepLatest(context.Background(), "events", -1); err == nil {
+		t.Fatalf("expected negative keep error")
+	}
+	if _, err := sink.PruneOlderThan(context.Background(), "missing", time.Now().UTC()); err == nil {
+		t.Fatalf("expected unknown table error")
+	}
+}

sinks/rabbitmq.go

@@ -1,42 +0,0 @@
-package sinks
-
-import (
-	"context"
-	"fmt"
-
-	"gitea.maximumdirect.net/ejr/feedkit/config"
-	"gitea.maximumdirect.net/ejr/feedkit/event"
-)
-
-type RabbitMQSink struct {
-	name     string
-	url      string
-	exchange string
-}
-
-func NewRabbitMQSinkFromConfig(cfg config.SinkConfig) (Sink, error) {
-	url, err := requireStringParam(cfg, "url")
-	if err != nil {
-		return nil, err
-	}
-	ex, err := requireStringParam(cfg, "exchange")
-	if err != nil {
-		return nil, err
-	}
-	return &RabbitMQSink{name: cfg.Name, url: url, exchange: ex}, nil
-}
-
-func (r *RabbitMQSink) Name() string { return r.name }
-
-func (r *RabbitMQSink) Consume(ctx context.Context, e event.Event) error {
-	_ = ctx
-
-	// Boundary validation: if something upstream violated invariants,
-	// surface it loudly rather than printing partial nonsense.
-	if err := e.Validate(); err != nil {
-		return fmt.Errorf("rabbitmq sink: invalid event: %w", err)
-	}
-
-	// TODO implement RabbitMQ publishing
-	return nil
-}

sinks/registry.go

@@ -2,6 +2,7 @@ package sinks
 
 import (
 	"fmt"
+	"strings"
 
 	"gitea.maximumdirect.net/ejr/feedkit/config"
 )
@@ -21,13 +22,40 @@ func NewRegistry() *Registry {
 }
 
 func (r *Registry) Register(driver string, f Factory) {
+	if r == nil {
+		panic("sinks.Registry.Register: registry cannot be nil")
+	}
+	driver = strings.TrimSpace(driver)
+	if driver == "" {
+		panic("sinks.Registry.Register: driver cannot be empty")
+	}
+	if f == nil {
+		panic(fmt.Sprintf("sinks.Registry.Register: factory cannot be nil (driver=%q)", driver))
+	}
+	if r.byDriver == nil {
+		r.byDriver = map[string]Factory{}
+	}
+	if _, exists := r.byDriver[driver]; exists {
+		panic(fmt.Sprintf("sinks.Registry.Register: driver %q already registered", driver))
+	}
 	r.byDriver[driver] = f
 }
 
 func (r *Registry) Build(cfg config.SinkConfig) (Sink, error) {
-	f, ok := r.byDriver[cfg.Driver]
-	if !ok {
-		return nil, fmt.Errorf("unknown sink driver: %q", cfg.Driver)
+	if r == nil {
+		return nil, fmt.Errorf("sinks registry is nil")
 	}
-	return f(cfg)
+	driver := strings.TrimSpace(cfg.Driver)
+	f, ok := r.byDriver[driver]
+	if !ok {
+		return nil, fmt.Errorf("unknown sink driver: %q", driver)
+	}
+	sink, err := f(cfg)
+	if err != nil {
+		return nil, fmt.Errorf("build sink %q: %w", driver, err)
+	}
+	if sink == nil {
+		return nil, fmt.Errorf("build sink %q: factory returned nil sink", driver)
+	}
+	return sink, nil
 }

sinks/registry_test.go

@@ -0,0 +1,126 @@
+package sinks
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+type testSink struct{ name string }
+
+func (s testSink) Name() string { return s.name }
+
+func (s testSink) Consume(context.Context, event.Event) error { return nil }
+
+func TestRegistryRegisterPanicsOnNilRegistry(t *testing.T) {
+	var r *Registry
+	defer func() {
+		if recover() == nil {
+			t.Fatalf("Register() expected panic on nil registry")
+		}
+	}()
+	r.Register("stdout", func(config.SinkConfig) (Sink, error) { return testSink{name: "stdout"}, nil })
+}
+
+func TestRegistryRegisterPanicsOnEmptyDriver(t *testing.T) {
+	r := NewRegistry()
+	defer func() {
+		if recover() == nil {
+			t.Fatalf("Register() expected panic on empty driver")
+		}
+	}()
+	r.Register("   ", func(config.SinkConfig) (Sink, error) { return testSink{name: "x"}, nil })
+}
+
+func TestRegistryRegisterPanicsOnNilFactory(t *testing.T) {
+	r := NewRegistry()
+	defer func() {
+		if recover() == nil {
+			t.Fatalf("Register() expected panic on nil factory")
+		}
+	}()
+	r.Register("stdout", nil)
+}
+
+func TestRegistryRegisterPanicsOnDuplicateDriver(t *testing.T) {
+	r := NewRegistry()
+	r.Register("stdout", func(config.SinkConfig) (Sink, error) { return testSink{name: "a"}, nil })
+
+	defer func() {
+		if recover() == nil {
+			t.Fatalf("Register() expected panic on duplicate driver")
+		}
+	}()
+	r.Register("stdout", func(config.SinkConfig) (Sink, error) { return testSink{name: "b"}, nil })
+}
+
+func TestRegistryBuildNilRegistryFails(t *testing.T) {
+	var r *Registry
+	_, err := r.Build(config.SinkConfig{Driver: "stdout"})
+	if err == nil {
+		t.Fatalf("Build() expected error for nil registry")
+	}
+	if !strings.Contains(err.Error(), "registry is nil") {
+		t.Fatalf("Build() error = %q, want registry is nil", err)
+	}
+}
+
+func TestRegistryBuildTrimsDriver(t *testing.T) {
+	r := NewRegistry()
+	r.Register("stdout", func(config.SinkConfig) (Sink, error) { return testSink{name: "stdout"}, nil })
+
+	sink, err := r.Build(config.SinkConfig{Name: "sink1", Driver: " stdout "})
+	if err != nil {
+		t.Fatalf("Build() error = %v", err)
+	}
+	if sink.Name() != "stdout" {
+		t.Fatalf("Build() sink name = %q, want stdout", sink.Name())
+	}
+}
+
+func TestRegistryBuildWrapsFactoryError(t *testing.T) {
+	r := NewRegistry()
+	r.Register("broken", func(config.SinkConfig) (Sink, error) { return nil, errors.New("boom") })
+
+	_, err := r.Build(config.SinkConfig{Driver: "broken"})
+	if err == nil {
+		t.Fatalf("Build() expected error")
+	}
+	if !strings.Contains(err.Error(), `build sink "broken": boom`) {
+		t.Fatalf("Build() error = %q", err)
+	}
+}
+
+func TestRegistryBuildRejectsNilSink(t *testing.T) {
+	r := NewRegistry()
+	r.Register("nil_sink", func(config.SinkConfig) (Sink, error) { return nil, nil })
+
+	_, err := r.Build(config.SinkConfig{Driver: "nil_sink"})
+	if err == nil {
+		t.Fatalf("Build() expected nil sink error")
+	}
+	if !strings.Contains(err.Error(), "factory returned nil sink") {
+		t.Fatalf("Build() error = %q", err)
+	}
+}
+
+func TestRegisterBuiltinsExposesExpectedDrivers(t *testing.T) {
+	r := NewRegistry()
+	RegisterBuiltins(r)
+
+	if len(r.byDriver) != 2 {
+		t.Fatalf("len(byDriver) = %d, want 2", len(r.byDriver))
+	}
+	for _, driver := range []string{"stdout", "nats"} {
+		if _, ok := r.byDriver[driver]; !ok {
+			t.Fatalf("builtins missing driver %q", driver)
+		}
+	}
+	if _, ok := r.byDriver["postgres"]; ok {
+		t.Fatalf("builtins unexpectedly registered postgres driver")
+	}
+}

sources/doc.go

@@ -0,0 +1,35 @@
+// Package sources defines feedkit's input-source abstractions and source
+// registry.
+//
+// External API surface:
+//   - Input: common source identity surface
+//   - PollSource: polling source interface
+//   - StreamSource: streaming source interface
+//   - Registry / NewRegistry: source driver registry and builders
+//   - HTTPSource / NewHTTPSource: reusable HTTP polling helper
+//
+// Source drivers are domain-specific and registered into Registry by driver name.
+// Registry can then build configured sources from config.SourceConfig.
+//
+// A single source may emit 0..N events per poll or stream iteration, and those
+// events may span multiple event kinds.
+//
+// Optional helpers from helpers.go:
+//   - DefaultEventID: default event ID policy for source implementations
+//   - SingleEvent: construct and validate a one-element event slice
+//   - ValidateExpectedKinds: compare configured expected kinds against source
+//     advertised kinds when metadata is available
+//
+// HTTP-backed polling sources can share NewHTTPSource for generic HTTP config
+// parsing and conditional GET behavior. The helper understands:
+//   - params.url
+//   - params.user_agent
+//   - params.conditional (optional, default true)
+//   - params.http_timeout (optional, default transport.DefaultHTTPTimeout)
+//   - params.http_response_body_limit_bytes (optional, default
+//     transport.DefaultHTTPResponseBodyLimitBytes)
+//
+// When validators are available, NewHTTPSource prefers ETag/If-None-Match and
+// falls back to Last-Modified/If-Modified-Since. A 304 Not Modified response is
+// treated as a successful unchanged poll.
+package sources

sources/helpers.go

@@ -0,0 +1,140 @@
+package sources
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+// DefaultEventID applies feedkit's default Event.ID policy:
+//
+//   - If upstream provides an ID, use it (trimmed).
+//   - Otherwise, ID is "<Source>:<EffectiveAt>" when available.
+//   - If EffectiveAt is unavailable, fall back to "<Source>:<EmittedAt>".
+//
+// Timestamps are encoded as RFC3339Nano in UTC.
+func DefaultEventID(upstreamID, sourceName string, effectiveAt *time.Time, emittedAt time.Time) string {
+	if id := strings.TrimSpace(upstreamID); id != "" {
+		return id
+	}
+
+	src := strings.TrimSpace(sourceName)
+	if src == "" {
+		src = "UNKNOWN_SOURCE"
+	}
+
+	if effectiveAt != nil && !effectiveAt.IsZero() {
+		return fmt.Sprintf("%s:%s", src, effectiveAt.UTC().Format(time.RFC3339Nano))
+	}
+
+	t := emittedAt.UTC()
+	if t.IsZero() {
+		t = time.Now().UTC()
+	}
+
+	return fmt.Sprintf("%s:%s", src, t.Format(time.RFC3339Nano))
+}
+
+// SingleEvent constructs, validates, and returns a slice containing exactly one event.
+func SingleEvent(
+	kind event.Kind,
+	sourceName string,
+	schema string,
+	id string,
+	emittedAt time.Time,
+	effectiveAt *time.Time,
+	payload any,
+) ([]event.Event, error) {
+	if emittedAt.IsZero() {
+		emittedAt = time.Now().UTC()
+	} else {
+		emittedAt = emittedAt.UTC()
+	}
+
+	e := event.Event{
+		ID:          id,
+		Kind:        kind,
+		Source:      sourceName,
+		EmittedAt:   emittedAt,
+		EffectiveAt: effectiveAt,
+		Schema:      schema,
+		Payload:     payload,
+	}
+
+	if err := e.Validate(); err != nil {
+		return nil, err
+	}
+
+	return []event.Event{e}, nil
+}
+
+// ValidateExpectedKinds checks that configured source expected kinds are a subset
+// of the kinds advertised by the built source, when the source exposes kind
+// metadata. If the source does not advertise kinds, the check is skipped.
+func ValidateExpectedKinds(cfg config.SourceConfig, in Input) error {
+	expectedKinds, err := parseExpectedKinds(cfg.ExpectedKinds())
+	if err != nil {
+		return err
+	}
+	if len(expectedKinds) == 0 {
+		return nil
+	}
+
+	advertisedKinds := advertisedSourceKinds(in)
+	if len(advertisedKinds) == 0 {
+		return nil
+	}
+
+	for kind := range expectedKinds {
+		if !advertisedKinds[kind] {
+			return fmt.Errorf(
+				"configured expected kind %q not advertised by source (configured=%v advertised=%v)",
+				kind,
+				sortedKinds(expectedKinds),
+				sortedKinds(advertisedKinds),
+			)
+		}
+	}
+	return nil
+}
+
+func parseExpectedKinds(raw []string) (map[event.Kind]bool, error) {
+	kinds := map[event.Kind]bool{}
+	for i, k := range raw {
+		kind, err := event.ParseKind(k)
+		if err != nil {
+			return nil, fmt.Errorf("invalid expected kind at index %d (%q): %w", i, k, err)
+		}
+		kinds[kind] = true
+	}
+	return kinds, nil
+}
+
+func advertisedSourceKinds(in Input) map[event.Kind]bool {
+	if in == nil {
+		return nil
+	}
+
+	kinds := map[event.Kind]bool{}
+	if ks, ok := in.(KindsSource); ok {
+		for _, kind := range ks.Kinds() {
+			kinds[kind] = true
+		}
+		return kinds
+	}
+
+	return nil
+}
+
+func sortedKinds(kindSet map[event.Kind]bool) []string {
+	out := make([]string, 0, len(kindSet))
+	for kind := range kindSet {
+		out = append(out, string(kind))
+	}
+	sort.Strings(out)
+	return out
+}

sources/helpers_test.go

@@ -0,0 +1,112 @@
+package sources
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+type testInput struct {
+	name string
+}
+
+func (s testInput) Name() string { return s.name }
+
+type testKindsSource struct {
+	testInput
+	kinds []event.Kind
+}
+
+func (s testKindsSource) Kinds() []event.Kind { return s.kinds }
+
+func TestValidateExpectedKindsSubsetAllowed(t *testing.T) {
+	cfg := config.SourceConfig{Kinds: []string{"observation"}}
+	in := testKindsSource{
+		testInput: testInput{name: "test"},
+		kinds:     []event.Kind{"observation", "forecast"},
+	}
+
+	if err := ValidateExpectedKinds(cfg, in); err != nil {
+		t.Fatalf("ValidateExpectedKinds() unexpected error: %v", err)
+	}
+}
+
+func TestValidateExpectedKindsMismatchFails(t *testing.T) {
+	cfg := config.SourceConfig{Kinds: []string{"alert"}}
+	in := testKindsSource{
+		testInput: testInput{name: "test"},
+		kinds:     []event.Kind{"observation", "forecast"},
+	}
+
+	err := ValidateExpectedKinds(cfg, in)
+	if err == nil {
+		t.Fatalf("ValidateExpectedKinds() expected mismatch error, got nil")
+	}
+	if !strings.Contains(err.Error(), "configured expected kind") {
+		t.Fatalf("ValidateExpectedKinds() error %q does not include expected message", err)
+	}
+}
+
+func TestValidateExpectedKindsNoMetadataSkipsCheck(t *testing.T) {
+	cfg := config.SourceConfig{Kinds: []string{"alert"}}
+	in := testInput{name: "test"}
+
+	if err := ValidateExpectedKinds(cfg, in); err != nil {
+		t.Fatalf("ValidateExpectedKinds() unexpected error: %v", err)
+	}
+}
+
+func TestDefaultEventIDUsesUpstreamID(t *testing.T) {
+	emittedAt := time.Date(2026, 3, 28, 15, 4, 5, 123, time.UTC)
+	got := DefaultEventID(" upstream-id ", "source", nil, emittedAt)
+	if got != "upstream-id" {
+		t.Fatalf("DefaultEventID() = %q, want upstream-id", got)
+	}
+}
+
+func TestDefaultEventIDPrefersEffectiveAt(t *testing.T) {
+	effectiveAt := time.Date(2026, 3, 28, 16, 4, 5, 987654321, time.FixedZone("x", -6*3600))
+	emittedAt := time.Date(2026, 3, 28, 15, 4, 5, 123, time.UTC)
+
+	got := DefaultEventID("", "source", &effectiveAt, emittedAt)
+	want := "source:" + effectiveAt.UTC().Format(time.RFC3339Nano)
+	if got != want {
+		t.Fatalf("DefaultEventID() = %q, want %q", got, want)
+	}
+}
+
+func TestDefaultEventIDFallsBackToEmittedAt(t *testing.T) {
+	emittedAt := time.Date(2026, 3, 28, 15, 4, 5, 123456789, time.FixedZone("y", 3*3600))
+	got := DefaultEventID("", "source", nil, emittedAt)
+	want := "source:" + emittedAt.UTC().Format(time.RFC3339Nano)
+	if got != want {
+		t.Fatalf("DefaultEventID() = %q, want %q", got, want)
+	}
+}
+
+func TestSingleEventBuildsValidatedSlice(t *testing.T) {
+	effectiveAt := time.Date(2026, 3, 28, 16, 0, 0, 0, time.UTC)
+	emittedAt := time.Date(2026, 3, 28, 15, 0, 0, 0, time.FixedZone("z", -5*3600))
+
+	got, err := SingleEvent(
+		event.Kind("observation"),
+		"source-a",
+		"raw.example.v1",
+		"evt-1",
+		emittedAt,
+		&effectiveAt,
+		map[string]any{"ok": true},
+	)
+	if err != nil {
+		t.Fatalf("SingleEvent() unexpected error: %v", err)
+	}
+	if len(got) != 1 {
+		t.Fatalf("SingleEvent() len = %d, want 1", len(got))
+	}
+	if got[0].EmittedAt != emittedAt.UTC() {
+		t.Fatalf("SingleEvent() emittedAt = %s, want %s", got[0].EmittedAt, emittedAt.UTC())
+	}
+}

sources/http.go

@@ -0,0 +1,152 @@
+package sources
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strings"
+	"sync"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/transport"
+)
+
+// HTTPSource is a reusable helper for polling HTTP-backed sources.
+//
+// It centralizes generic source config parsing (`params.url`,
+// `params.user_agent`, and optional `params.conditional`), default HTTP client
+// setup, and conditional GET validator handling. Concrete daemon sources remain
+// responsible for decoding the response body and constructing events.
+type HTTPSource struct {
+	Driver                 string
+	Name                   string
+	URL                    string
+	UserAgent              string
+	Accept                 string
+	Conditional            bool
+	ResponseBodyLimitBytes int64
+	Client                 *http.Client
+
+	mu         sync.Mutex
+	validators transport.HTTPValidators
+}
+
+// NewHTTPSource builds a generic HTTP polling helper from SourceConfig.
+//
+// Required params:
+//   - params.url
+//   - params.user_agent
+//
+// Optional params:
+//   - params.conditional (default true): enable conditional GET using cached
+//     ETag / Last-Modified validators
+func NewHTTPSource(driver string, cfg config.SourceConfig, accept string) (*HTTPSource, error) {
+	name := strings.TrimSpace(cfg.Name)
+	if name == "" {
+		return nil, fmt.Errorf("%s: name is required", driver)
+	}
+	if cfg.Params == nil {
+		return nil, fmt.Errorf("%s %q: params are required (need params.url and params.user_agent)", driver, cfg.Name)
+	}
+
+	url, ok := cfg.ParamString("url", "URL")
+	if !ok {
+		return nil, fmt.Errorf("%s %q: params.url is required", driver, cfg.Name)
+	}
+
+	userAgent, ok := cfg.ParamString("user_agent", "userAgent")
+	if !ok {
+		return nil, fmt.Errorf("%s %q: params.user_agent is required", driver, cfg.Name)
+	}
+
+	conditional := true
+	if _, exists := cfg.Params["conditional"]; exists {
+		var ok bool
+		conditional, ok = cfg.ParamBool("conditional")
+		if !ok {
+			return nil, fmt.Errorf("source %q: params.conditional must be a boolean", cfg.Name)
+		}
+	}
+
+	timeout := transport.DefaultHTTPTimeout
+	if _, exists := cfg.Params["http_timeout"]; exists {
+		var ok bool
+		timeout, ok = cfg.ParamDuration("http_timeout")
+		if !ok || timeout <= 0 {
+			return nil, fmt.Errorf("source %q: params.http_timeout must be a positive duration", cfg.Name)
+		}
+	}
+
+	bodyLimit := transport.DefaultHTTPResponseBodyLimitBytes
+	if _, exists := cfg.Params["http_response_body_limit_bytes"]; exists {
+		rawLimit, ok := cfg.ParamInt("http_response_body_limit_bytes")
+		if !ok || rawLimit <= 0 {
+			return nil, fmt.Errorf("source %q: params.http_response_body_limit_bytes must be a positive integer", cfg.Name)
+		}
+		bodyLimit = int64(rawLimit)
+	}
+
+	return &HTTPSource{
+		Driver:                 driver,
+		Name:                   name,
+		URL:                    url,
+		UserAgent:              userAgent,
+		Accept:                 accept,
+		Conditional:            conditional,
+		ResponseBodyLimitBytes: bodyLimit,
+		Client:                 transport.NewHTTPClient(timeout),
+	}, nil
+}
+
+// FetchBytesIfChanged fetches the configured URL and reports whether the
+// upstream content changed. An unchanged 304 response returns changed=false
+// with no body and no error.
+func (s *HTTPSource) FetchBytesIfChanged(ctx context.Context) ([]byte, bool, error) {
+	client := s.Client
+	if client == nil {
+		client = transport.NewHTTPClient(transport.DefaultHTTPTimeout)
+	}
+
+	s.mu.Lock()
+	validators := s.validators
+	s.mu.Unlock()
+
+	bodyLimit := s.ResponseBodyLimitBytes
+	if bodyLimit <= 0 {
+		bodyLimit = transport.DefaultHTTPResponseBodyLimitBytes
+	}
+
+	body, changed, next, err := transport.FetchBodyIfChangedWithLimit(
+		ctx,
+		client,
+		s.URL,
+		s.UserAgent,
+		s.Accept,
+		s.Conditional,
+		validators,
+		bodyLimit,
+	)
+	if err != nil {
+		return nil, false, fmt.Errorf("%s %q: %w", s.Driver, s.Name, err)
+	}
+
+	if s.Conditional {
+		s.mu.Lock()
+		s.validators = next
+		s.mu.Unlock()
+	}
+
+	return body, changed, nil
+}
+
+// FetchJSONIfChanged fetches the configured URL and returns the raw response
+// body as json.RawMessage when content changed. An unchanged 304 response
+// returns changed=false with a nil body and no error.
+func (s *HTTPSource) FetchJSONIfChanged(ctx context.Context) (json.RawMessage, bool, error) {
+	body, changed, err := s.FetchBytesIfChanged(ctx)
+	if err != nil || !changed {
+		return nil, changed, err
+	}
+	return json.RawMessage(body), true, nil
+}

sources/http_test.go

@@ -0,0 +1,260 @@
+package sources
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/transport"
+)
+
+func TestNewHTTPSourceConditionalDefaultsTrue(t *testing.T) {
+	src, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":        "https://example.invalid",
+			"user_agent": "test-agent",
+		},
+	}, "application/json")
+	if err != nil {
+		t.Fatalf("NewHTTPSource() error = %v", err)
+	}
+	if !src.Conditional {
+		t.Fatalf("Conditional = false, want true")
+	}
+}
+
+func TestNewHTTPSourceRejectsInvalidConditional(t *testing.T) {
+	_, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":         "https://example.invalid",
+			"user_agent":  "test-agent",
+			"conditional": "sometimes",
+		},
+	}, "application/json")
+	if err == nil {
+		t.Fatalf("NewHTTPSource() error = nil, want error")
+	}
+	if !strings.Contains(err.Error(), "params.conditional must be a boolean") {
+		t.Fatalf("NewHTTPSource() error = %q, want params.conditional must be a boolean", err)
+	}
+}
+
+func TestNewHTTPSourceConditionalCanBeExplicitlyFalse(t *testing.T) {
+	src, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":         "https://example.invalid",
+			"user_agent":  "test-agent",
+			"conditional": false,
+		},
+	}, "application/json")
+	if err != nil {
+		t.Fatalf("NewHTTPSource() error = %v", err)
+	}
+	if src.Conditional {
+		t.Fatalf("Conditional = true, want false")
+	}
+}
+
+func TestNewHTTPSourceHTTPTimeoutOverride(t *testing.T) {
+	src, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":          "https://example.invalid",
+			"user_agent":   "test-agent",
+			"http_timeout": "250ms",
+		},
+	}, "application/json")
+	if err != nil {
+		t.Fatalf("NewHTTPSource() error = %v", err)
+	}
+	if src.Client == nil {
+		t.Fatalf("Client = nil")
+	}
+	if src.Client.Timeout != 250*time.Millisecond {
+		t.Fatalf("Client.Timeout = %s, want 250ms", src.Client.Timeout)
+	}
+}
+
+func TestNewHTTPSourceBodyLimitOverride(t *testing.T) {
+	src, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":                            "https://example.invalid",
+			"user_agent":                     "test-agent",
+			"http_response_body_limit_bytes": 12345,
+		},
+	}, "application/json")
+	if err != nil {
+		t.Fatalf("NewHTTPSource() error = %v", err)
+	}
+	if src.ResponseBodyLimitBytes != 12345 {
+		t.Fatalf("ResponseBodyLimitBytes = %d, want 12345", src.ResponseBodyLimitBytes)
+	}
+}
+
+func TestNewHTTPSourceRejectsInvalidHTTPTimeout(t *testing.T) {
+	_, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":          "https://example.invalid",
+			"user_agent":   "test-agent",
+			"http_timeout": "soon",
+		},
+	}, "application/json")
+	if err == nil {
+		t.Fatalf("NewHTTPSource() error = nil, want error")
+	}
+	if !strings.Contains(err.Error(), "params.http_timeout must be a positive duration") {
+		t.Fatalf("NewHTTPSource() error = %q", err)
+	}
+}
+
+func TestNewHTTPSourceRejectsInvalidBodyLimit(t *testing.T) {
+	_, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":                            "https://example.invalid",
+			"user_agent":                     "test-agent",
+			"http_response_body_limit_bytes": "abc",
+		},
+	}, "application/json")
+	if err == nil {
+		t.Fatalf("NewHTTPSource() error = nil, want error")
+	}
+	if !strings.Contains(err.Error(), "params.http_response_body_limit_bytes must be a positive integer") {
+		t.Fatalf("NewHTTPSource() error = %q", err)
+	}
+}
+
+func TestHTTPSourceFetchJSONIfChanged(t *testing.T) {
+	var call int
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		call++
+		switch call {
+		case 1:
+			w.Header().Set("ETag", `"v1"`)
+			_, _ = w.Write([]byte(`{"ok":true}`))
+		case 2:
+			if got := r.Header.Get("If-None-Match"); got != `"v1"` {
+				t.Fatalf("second request If-None-Match = %q", got)
+			}
+			w.WriteHeader(http.StatusNotModified)
+		default:
+			t.Fatalf("unexpected call count %d", call)
+		}
+	}))
+	defer srv.Close()
+
+	src, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":        srv.URL,
+			"user_agent": "test-agent",
+		},
+	}, "application/json")
+	if err != nil {
+		t.Fatalf("NewHTTPSource() error = %v", err)
+	}
+
+	raw, changed, err := src.FetchJSONIfChanged(context.Background())
+	if err != nil {
+		t.Fatalf("first FetchJSONIfChanged() error = %v", err)
+	}
+	if !changed {
+		t.Fatalf("first FetchJSONIfChanged() changed = false, want true")
+	}
+	if got := string(raw); got != `{"ok":true}` {
+		t.Fatalf("first FetchJSONIfChanged() body = %q", got)
+	}
+
+	raw, changed, err = src.FetchJSONIfChanged(context.Background())
+	if err != nil {
+		t.Fatalf("second FetchJSONIfChanged() error = %v", err)
+	}
+	if changed {
+		t.Fatalf("second FetchJSONIfChanged() changed = true, want false")
+	}
+	if raw != nil {
+		t.Fatalf("second FetchJSONIfChanged() body = %q, want nil", string(raw))
+	}
+}
+
+func TestHTTPSourceFetchJSONIfChangedHonorsBodyLimitOverride(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":true}`))
+	}))
+	defer srv.Close()
+
+	src, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":                            srv.URL,
+			"user_agent":                     "test-agent",
+			"http_response_body_limit_bytes": 4,
+		},
+	}, "application/json")
+	if err != nil {
+		t.Fatalf("NewHTTPSource() error = %v", err)
+	}
+
+	_, _, err = src.FetchJSONIfChanged(context.Background())
+	if err == nil {
+		t.Fatalf("FetchJSONIfChanged() error = nil, want limit error")
+	}
+	if !strings.Contains(err.Error(), "response body too large") {
+		t.Fatalf("FetchJSONIfChanged() error = %q", err)
+	}
+}
+
+func TestNewHTTPSourceUsesDefaultBodyLimitWhenUnset(t *testing.T) {
+	src, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":        "https://example.invalid",
+			"user_agent": "test-agent",
+		},
+	}, "application/json")
+	if err != nil {
+		t.Fatalf("NewHTTPSource() error = %v", err)
+	}
+	if src.ResponseBodyLimitBytes != transport.DefaultHTTPResponseBodyLimitBytes {
+		t.Fatalf("ResponseBodyLimitBytes = %d, want %d", src.ResponseBodyLimitBytes, transport.DefaultHTTPResponseBodyLimitBytes)
+	}
+}
+
+func TestNewHTTPSourceUsesDefaultTimeoutWhenUnset(t *testing.T) {
+	src, err := NewHTTPSource("test_driver", config.SourceConfig{
+		Name:   "test-source",
+		Driver: "test_driver",
+		Params: map[string]any{
+			"url":        "https://example.invalid",
+			"user_agent": "test-agent",
+		},
+	}, "application/json")
+	if err != nil {
+		t.Fatalf("NewHTTPSource() error = %v", err)
+	}
+	if src.Client == nil {
+		t.Fatalf("Client = nil")
+	}
+	if src.Client.Timeout != transport.DefaultHTTPTimeout {
+		t.Fatalf("Client.Timeout = %s, want %s", src.Client.Timeout, transport.DefaultHTTPTimeout)
+	}
+}

sources/registry.go

@@ -7,43 +7,115 @@ import (
 	"gitea.maximumdirect.net/ejr/feedkit/config"
 )
 
-// Factory constructs a configured Source instance from config.
+// PollFactory constructs a configured PollSource instance from config.
 //
 // This is how concrete daemons (weatherfeeder/newsfeeder/...) register their
 // domain-specific source drivers (Open-Meteo, NWS, RSS, etc.) while feedkit
 // remains domain-agnostic.
-type Factory func(cfg config.SourceConfig) (Source, error)
+type PollFactory func(cfg config.SourceConfig) (PollSource, error)
+type StreamFactory func(cfg config.SourceConfig) (StreamSource, error)
 
 type Registry struct {
-	byDriver map[string]Factory
+	byPollDriver   map[string]PollFactory
+	byStreamDriver map[string]StreamFactory
 }
 
 func NewRegistry() *Registry {
-	return &Registry{byDriver: map[string]Factory{}}
+	return &Registry{
+		byPollDriver:   map[string]PollFactory{},
+		byStreamDriver: map[string]StreamFactory{},
+	}
 }
 
-// Register associates a driver name (e.g. "openmeteo_observation") with a factory.
-//
-// The driver string is the "lookup key" used by config.sources[].driver.
-func (r *Registry) Register(driver string, f Factory) {
+// RegisterPoll associates a driver name with a polling-source factory.
+func (r *Registry) RegisterPoll(driver string, f PollFactory) {
 	driver = strings.TrimSpace(driver)
 	if driver == "" {
 		// Panic is appropriate here: registering an empty driver is always a programmer error,
 		// and it will lead to extremely confusing runtime behavior if allowed.
-		panic("sources.Registry.Register: driver cannot be empty")
+		panic("sources.Registry.RegisterPoll: driver cannot be empty")
 	}
 	if f == nil {
-		panic(fmt.Sprintf("sources.Registry.Register: factory cannot be nil (driver=%q)", driver))
+		panic(fmt.Sprintf("sources.Registry.RegisterPoll: factory cannot be nil (driver=%q)", driver))
 	}
-
-	r.byDriver[driver] = f
+	if _, exists := r.byStreamDriver[driver]; exists {
+		panic(fmt.Sprintf("sources.Registry.RegisterPoll: driver %q already registered as a stream source", driver))
+	}
+	if _, exists := r.byPollDriver[driver]; exists {
+		panic(fmt.Sprintf("sources.Registry.RegisterPoll: driver %q already registered as a polling source", driver))
+	}
+	r.byPollDriver[driver] = f
 }
 
-// Build constructs a Source from a SourceConfig by looking up cfg.Driver.
-func (r *Registry) Build(cfg config.SourceConfig) (Source, error) {
-	f, ok := r.byDriver[cfg.Driver]
+// RegisterStream is the StreamSource equivalent of Register.
+func (r *Registry) RegisterStream(driver string, f StreamFactory) {
+	driver = strings.TrimSpace(driver)
+	if driver == "" {
+		panic("sources.Registry.RegisterStream: driver cannot be empty")
+	}
+	if f == nil {
+		panic(fmt.Sprintf("sources.Registry.RegisterStream: factory cannot be nil (driver=%q)", driver))
+	}
+	if _, exists := r.byPollDriver[driver]; exists {
+		panic(fmt.Sprintf("sources.Registry.RegisterStream: driver %q already registered as a polling source", driver))
+	}
+	if _, exists := r.byStreamDriver[driver]; exists {
+		panic(fmt.Sprintf("sources.Registry.RegisterStream: driver %q already registered as a stream source", driver))
+	}
+	r.byStreamDriver[driver] = f
+}
+
+// BuildPoll constructs a polling source from a SourceConfig by looking up cfg.Driver.
+func (r *Registry) BuildPoll(cfg config.SourceConfig) (PollSource, error) {
+	driver := strings.TrimSpace(cfg.Driver)
+	if cfg.Mode.Normalize() == config.SourceModeStream {
+		return nil, fmt.Errorf("source %q mode=stream cannot be built as polling source", cfg.Name)
+	}
+
+	f, ok := r.byPollDriver[driver]
 	if !ok {
-		return nil, fmt.Errorf("unknown source driver: %q", cfg.Driver)
+		if _, streamExists := r.byStreamDriver[driver]; streamExists {
+			return nil, fmt.Errorf("source driver %q is stream-only; cannot build as polling source", driver)
+		}
+		return nil, fmt.Errorf("unknown source driver: %q", driver)
 	}
 	return f(cfg)
 }
+
+// BuildInput can return either a polling Source or a StreamSource.
+func (r *Registry) BuildInput(cfg config.SourceConfig) (Input, error) {
+	driver := strings.TrimSpace(cfg.Driver)
+	mode := cfg.Mode.Normalize()
+	if mode != config.SourceModeAuto && mode != config.SourceModePoll && mode != config.SourceModeStream {
+		return nil, fmt.Errorf("source %q has invalid mode %q (expected \"poll\" or \"stream\")", cfg.Name, cfg.Mode)
+	}
+
+	switch mode {
+	case config.SourceModePoll:
+		f, ok := r.byPollDriver[driver]
+		if !ok {
+			if _, streamExists := r.byStreamDriver[driver]; streamExists {
+				return nil, fmt.Errorf("source %q mode=poll conflicts with stream-only driver %q", cfg.Name, driver)
+			}
+			return nil, fmt.Errorf("unknown source driver: %q", driver)
+		}
+		return f(cfg)
+	case config.SourceModeStream:
+		f, ok := r.byStreamDriver[driver]
+		if !ok {
+			if _, pollExists := r.byPollDriver[driver]; pollExists {
+				return nil, fmt.Errorf("source %q mode=stream conflicts with polling driver %q", cfg.Name, driver)
+			}
+			return nil, fmt.Errorf("unknown source driver: %q", driver)
+		}
+		return f(cfg)
+	}
+
+	if f, ok := r.byStreamDriver[driver]; ok {
+		return f(cfg)
+	}
+	if f, ok := r.byPollDriver[driver]; ok {
+		return f(cfg)
+	}
+	return nil, fmt.Errorf("unknown source driver: %q", driver)
+}

sources/registry_test.go

@@ -0,0 +1,84 @@
+package sources
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+type testPollSource struct{ name string }
+
+func (s testPollSource) Name() string { return s.name }
+func (s testPollSource) Poll(context.Context) ([]event.Event, error) {
+	return nil, nil
+}
+
+type testStreamSource struct{ name string }
+
+func (s testStreamSource) Name() string { return s.name }
+func (s testStreamSource) Run(context.Context, chan<- event.Event) error {
+	return nil
+}
+
+func TestRegistryBuildInputModeConflicts(t *testing.T) {
+	r := NewRegistry()
+	r.RegisterPoll("poll_driver", func(cfg config.SourceConfig) (PollSource, error) {
+		return testPollSource{name: cfg.Name}, nil
+	})
+	r.RegisterStream("stream_driver", func(cfg config.SourceConfig) (StreamSource, error) {
+		return testStreamSource{name: cfg.Name}, nil
+	})
+
+	_, err := r.BuildInput(config.SourceConfig{
+		Name:   "s1",
+		Driver: "stream_driver",
+		Mode:   config.SourceModePoll,
+	})
+	if err == nil {
+		t.Fatalf("expected mode conflict error, got nil")
+	}
+	if !strings.Contains(err.Error(), "mode=poll") {
+		t.Fatalf("expected poll conflict error, got: %v", err)
+	}
+
+	_, err = r.BuildInput(config.SourceConfig{
+		Name:   "s2",
+		Driver: "poll_driver",
+		Mode:   config.SourceModeStream,
+	})
+	if err == nil {
+		t.Fatalf("expected mode conflict error, got nil")
+	}
+	if !strings.Contains(err.Error(), "mode=stream") {
+		t.Fatalf("expected stream conflict error, got: %v", err)
+	}
+}
+
+func TestRegistryBuildInputAutoByDriverType(t *testing.T) {
+	r := NewRegistry()
+	r.RegisterPoll("poll_driver", func(cfg config.SourceConfig) (PollSource, error) {
+		return testPollSource{name: cfg.Name}, nil
+	})
+	r.RegisterStream("stream_driver", func(cfg config.SourceConfig) (StreamSource, error) {
+		return testStreamSource{name: cfg.Name}, nil
+	})
+
+	src, err := r.BuildInput(config.SourceConfig{Name: "p", Driver: "poll_driver"})
+	if err != nil {
+		t.Fatalf("BuildInput poll auto failed: %v", err)
+	}
+	if _, ok := src.(PollSource); !ok {
+		t.Fatalf("expected PollSource, got %T", src)
+	}
+
+	src, err = r.BuildInput(config.SourceConfig{Name: "s", Driver: "stream_driver"})
+	if err != nil {
+		t.Fatalf("BuildInput stream auto failed: %v", err)
+	}
+	if _, ok := src.(StreamSource); !ok {
+		t.Fatalf("expected StreamSource, got %T", src)
+	}
+}

sources/source.go

@@ -6,25 +6,41 @@ import (
 	"gitea.maximumdirect.net/ejr/feedkit/event"
 )
 
-// Source is a configured polling job that emits 0..N events per poll.
+// Input is the common surface shared by all source types.
 //
-// Source implementations live in domain modules (weatherfeeder/newsfeeder/...)
+// A source may be polling (PollSource) or event-driven (StreamSource).
+// Both source types emit domain-agnostic event.Event values.
+type Input interface {
+	Name() string
+}
+
+// PollSource is a configured polling source that emits 0..N events per poll.
+//
+// PollSource implementations live in domain modules (weatherfeeder/newsfeeder/...)
 // and are registered into a feedkit sources.Registry.
 //
-// feedkit infrastructure treats Source as opaque; it just calls Poll()
+// feedkit infrastructure treats PollSource as opaque; it just calls Poll()
 // on the configured cadence and publishes the resulting events.
-type Source interface {
+type PollSource interface {
 	// Name is the configured source name (used for logs and included in emitted events).
 	Name() string
 
-	// Kind is the "primary kind" emitted by this source.
-	//
-	// This is mainly useful as a *safety check* (e.g. config says kind=forecast but
-	// driver emits observation). Some future sources may emit multiple kinds; if/when
-	// that happens, we can evolve this interface (e.g., make Kind optional, or remove it).
-	Kind() event.Kind
-
-	// Poll fetches from upstream and returns 0..N events.
+	// Poll fetches/processes one input batch and returns 0..N events.
+	// A single poll can emit multiple event kinds.
 	// Implementations should honor ctx.Done() for network calls and other I/O.
 	Poll(ctx context.Context) ([]event.Event, error)
 }
+
+// StreamSource is an event-driven source (NATS/RabbitMQ/MQTT/etc).
+//
+// Run should block, producing events into `out` until ctx is cancelled or a fatal error occurs.
+// It MUST NOT close out (the scheduler/daemon owns the bus).
+type StreamSource interface {
+	Input
+	Run(ctx context.Context, out chan<- event.Event) error
+}
+
+// KindsSource is an optional interface for sources that advertise multiple kinds.
+type KindsSource interface {
+	Kinds() []event.Kind
+}

transport/http.go

@@ -6,15 +6,16 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strings"
 	"time"
 )
 
-// maxResponseBodyBytes is a hard safety limit on HTTP response bodies.
+// DefaultHTTPResponseBodyLimitBytes is a hard safety limit on HTTP response bodies.
 // API responses should be small, so this protects us from accidental
 // or malicious large responses.
-const maxResponseBodyBytes = 2 << 21 // 4 MiB
+const DefaultHTTPResponseBodyLimitBytes int64 = 2 << 21 // 4 MiB
 
-// DefaultHTTPTimeout is the standard timeout used by weatherfeeder HTTP sources.
+// DefaultHTTPTimeout is the standard timeout used by HTTP sources.
 // Individual drivers may override this if they have a specific need.
 const DefaultHTTPTimeout = 10 * time.Second
 
@@ -28,7 +29,95 @@ func NewHTTPClient(timeout time.Duration) *http.Client {
 }
 
 func FetchBody(ctx context.Context, client *http.Client, url, userAgent, accept string) ([]byte, error) {
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	return FetchBodyWithLimit(ctx, client, url, userAgent, accept, DefaultHTTPResponseBodyLimitBytes)
+}
+
+func FetchBodyWithLimit(ctx context.Context, client *http.Client, url, userAgent, accept string, bodyLimitBytes int64) ([]byte, error) {
+	res, err := doRequest(ctx, client, http.MethodGet, url, userAgent, accept, "", "")
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode < 200 || res.StatusCode >= 300 {
+		return nil, fmt.Errorf("HTTP %s", res.Status)
+	}
+
+	return readValidatedBody(res.Body, bodyLimitBytes)
+}
+
+// HTTPValidators are cache validators learned from prior successful GET responses.
+//
+// ETag is preferred when present. LastModified is used as a fallback validator
+// when ETag is unavailable.
+type HTTPValidators struct {
+	ETag         string
+	LastModified string
+}
+
+// FetchBodyIfChanged performs an HTTP GET and opportunistically uses conditional
+// request headers based on the provided validators.
+//
+// Behavior:
+//   - if conditional is false, this behaves like a normal GET and leaves validators unchanged
+//   - if validators.ETag is set, sends If-None-Match
+//   - else if validators.LastModified is set, sends If-Modified-Since
+//   - 304 Not Modified is treated as success with changed=false and no body
+//   - 200 responses are treated as changed=true and still enforce the normal body checks
+//
+// Returned validators reflect any updates learned from the response headers.
+func FetchBodyIfChanged(
+	ctx context.Context,
+	client *http.Client,
+	url, userAgent, accept string,
+	conditional bool,
+	validators HTTPValidators,
+) ([]byte, bool, HTTPValidators, error) {
+	return FetchBodyIfChangedWithLimit(ctx, client, url, userAgent, accept, conditional, validators, DefaultHTTPResponseBodyLimitBytes)
+}
+
+func FetchBodyIfChangedWithLimit(
+	ctx context.Context,
+	client *http.Client,
+	url, userAgent, accept string,
+	conditional bool,
+	validators HTTPValidators,
+	bodyLimitBytes int64,
+) ([]byte, bool, HTTPValidators, error) {
+	headerName, headerValue := conditionalHeader(conditional, validators)
+
+	res, err := doRequest(ctx, client, http.MethodGet, url, userAgent, accept, headerName, headerValue)
+	if err != nil {
+		return nil, false, validators, err
+	}
+	defer res.Body.Close()
+
+	switch res.StatusCode {
+	case http.StatusNotModified:
+		if conditional {
+			validators = refreshValidators(validators, res.Header)
+		}
+		return nil, false, validators, nil
+	default:
+		if res.StatusCode < 200 || res.StatusCode >= 300 {
+			return nil, false, validators, fmt.Errorf("HTTP %s", res.Status)
+		}
+	}
+
+	b, err := readValidatedBody(res.Body, bodyLimitBytes)
+	if err != nil {
+		return nil, false, validators, err
+	}
+
+	if conditional {
+		validators = replaceValidators(res.Header)
+	}
+
+	return b, true, validators, nil
+}
+
+func doRequest(ctx context.Context, client *http.Client, method, url, userAgent, accept, headerName, headerValue string) (*http.Response, error) {
+	req, err := http.NewRequestWithContext(ctx, method, url, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -39,19 +128,50 @@ func FetchBody(ctx context.Context, client *http.Client, url, userAgent, accept
 	if accept != "" {
 		req.Header.Set("Accept", accept)
 	}
-
-	res, err := client.Do(req)
-	if err != nil {
-		return nil, err
-	}
-	defer res.Body.Close()
-
-	if res.StatusCode < 200 || res.StatusCode >= 300 {
-		return nil, fmt.Errorf("HTTP %s", res.Status)
+	if headerName != "" && headerValue != "" {
+		req.Header.Set(headerName, headerValue)
 	}
 
-	// Read at most maxResponseBodyBytes + 1 so we can detect overflow.
-	limited := io.LimitReader(res.Body, maxResponseBodyBytes+1)
+	return client.Do(req)
+}
+
+func conditionalHeader(enabled bool, validators HTTPValidators) (string, string) {
+	if !enabled {
+		return "", ""
+	}
+	if etag := strings.TrimSpace(validators.ETag); etag != "" {
+		return "If-None-Match", etag
+	}
+	if lastModified := strings.TrimSpace(validators.LastModified); lastModified != "" {
+		return "If-Modified-Since", lastModified
+	}
+	return "", ""
+}
+
+func replaceValidators(header http.Header) HTTPValidators {
+	return HTTPValidators{
+		ETag:         strings.TrimSpace(header.Get("ETag")),
+		LastModified: strings.TrimSpace(header.Get("Last-Modified")),
+	}
+}
+
+func refreshValidators(current HTTPValidators, header http.Header) HTTPValidators {
+	if etag := strings.TrimSpace(header.Get("ETag")); etag != "" {
+		current.ETag = etag
+	}
+	if lastModified := strings.TrimSpace(header.Get("Last-Modified")); lastModified != "" {
+		current.LastModified = lastModified
+	}
+	return current
+}
+
+func readValidatedBody(r io.Reader, bodyLimitBytes int64) ([]byte, error) {
+	if bodyLimitBytes <= 0 {
+		bodyLimitBytes = DefaultHTTPResponseBodyLimitBytes
+	}
+
+	// Read at most bodyLimitBytes + 1 so we can detect overflow.
+	limited := io.LimitReader(r, bodyLimitBytes+1)
 
 	b, err := io.ReadAll(limited)
 	if err != nil {
@@ -62,8 +182,8 @@ func FetchBody(ctx context.Context, client *http.Client, url, userAgent, accept
 		return nil, fmt.Errorf("empty response body")
 	}
 
-	if len(b) > maxResponseBodyBytes {
-		return nil, fmt.Errorf("response body too large (>%d bytes)", maxResponseBodyBytes)
+	if int64(len(b)) > bodyLimitBytes {
+		return nil, fmt.Errorf("response body too large (>%d bytes)", bodyLimitBytes)
 	}
 
 	return b, nil

transport/http_test.go

@@ -0,0 +1,232 @@
+package transport
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestFetchBodyIfChangedPrefersETagAndTreats304AsUnchanged(t *testing.T) {
+	t.Helper()
+
+	var call int
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		call++
+		switch call {
+		case 1:
+			if got := r.Header.Get("If-None-Match"); got != "" {
+				t.Fatalf("first request If-None-Match = %q, want empty", got)
+			}
+			if got := r.Header.Get("If-Modified-Since"); got != "" {
+				t.Fatalf("first request If-Modified-Since = %q, want empty", got)
+			}
+			w.Header().Set("ETag", `"v1"`)
+			w.Header().Set("Last-Modified", "Mon, 02 Jan 2006 15:04:05 GMT")
+			_, _ = w.Write([]byte(`{"ok":true}`))
+		case 2:
+			if got := r.Header.Get("If-None-Match"); got != `"v1"` {
+				t.Fatalf("second request If-None-Match = %q, want %q", got, `"v1"`)
+			}
+			if got := r.Header.Get("If-Modified-Since"); got != "" {
+				t.Fatalf("second request If-Modified-Since = %q, want empty when ETag is cached", got)
+			}
+			w.WriteHeader(http.StatusNotModified)
+		default:
+			t.Fatalf("unexpected call count %d", call)
+		}
+	}))
+	defer srv.Close()
+
+	validators := HTTPValidators{}
+	body, changed, next, err := FetchBodyIfChanged(context.Background(), srv.Client(), srv.URL, "test-agent", "application/json", true, validators)
+	if err != nil {
+		t.Fatalf("first FetchBodyIfChanged() error = %v", err)
+	}
+	if !changed {
+		t.Fatalf("first FetchBodyIfChanged() changed = false, want true")
+	}
+	if got := string(body); got != `{"ok":true}` {
+		t.Fatalf("first FetchBodyIfChanged() body = %q", got)
+	}
+	if got := next.ETag; got != `"v1"` {
+		t.Fatalf("cached ETag = %q, want %q", got, `"v1"`)
+	}
+	if got := next.LastModified; got != "Mon, 02 Jan 2006 15:04:05 GMT" {
+		t.Fatalf("cached Last-Modified = %q", got)
+	}
+
+	body, changed, next, err = FetchBodyIfChanged(context.Background(), srv.Client(), srv.URL, "test-agent", "application/json", true, next)
+	if err != nil {
+		t.Fatalf("second FetchBodyIfChanged() error = %v", err)
+	}
+	if changed {
+		t.Fatalf("second FetchBodyIfChanged() changed = true, want false")
+	}
+	if body != nil {
+		t.Fatalf("second FetchBodyIfChanged() body = %q, want nil", string(body))
+	}
+	if got := next.ETag; got != `"v1"` {
+		t.Fatalf("cached ETag after 304 = %q, want %q", got, `"v1"`)
+	}
+}
+
+func TestFetchBodyIfChangedFallsBackToIfModifiedSince(t *testing.T) {
+	t.Helper()
+
+	var call int
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		call++
+		switch call {
+		case 1:
+			w.Header().Set("Last-Modified", "Tue, 03 Jan 2006 15:04:05 GMT")
+			_, _ = w.Write([]byte(`first`))
+		case 2:
+			if got := r.Header.Get("If-None-Match"); got != "" {
+				t.Fatalf("second request If-None-Match = %q, want empty", got)
+			}
+			if got := r.Header.Get("If-Modified-Since"); got != "Tue, 03 Jan 2006 15:04:05 GMT" {
+				t.Fatalf("second request If-Modified-Since = %q", got)
+			}
+			w.WriteHeader(http.StatusNotModified)
+		default:
+			t.Fatalf("unexpected call count %d", call)
+		}
+	}))
+	defer srv.Close()
+
+	_, changed, validators, err := FetchBodyIfChanged(context.Background(), srv.Client(), srv.URL, "test-agent", "", true, HTTPValidators{})
+	if err != nil {
+		t.Fatalf("first FetchBodyIfChanged() error = %v", err)
+	}
+	if !changed {
+		t.Fatalf("first FetchBodyIfChanged() changed = false, want true")
+	}
+	if got := validators.LastModified; got != "Tue, 03 Jan 2006 15:04:05 GMT" {
+		t.Fatalf("cached Last-Modified = %q", got)
+	}
+
+	_, changed, _, err = FetchBodyIfChanged(context.Background(), srv.Client(), srv.URL, "test-agent", "", true, validators)
+	if err != nil {
+		t.Fatalf("second FetchBodyIfChanged() error = %v", err)
+	}
+	if changed {
+		t.Fatalf("second FetchBodyIfChanged() changed = true, want false")
+	}
+}
+
+func TestFetchBodyIfChangedClearsValidatorsOn200WithoutValidators(t *testing.T) {
+	t.Helper()
+
+	var call int
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		call++
+		switch call {
+		case 1:
+			w.Header().Set("ETag", `"v1"`)
+			_, _ = w.Write([]byte(`first`))
+		case 2:
+			if got := r.Header.Get("If-None-Match"); got != `"v1"` {
+				t.Fatalf("second request If-None-Match = %q", got)
+			}
+			_, _ = w.Write([]byte(`second`))
+		case 3:
+			if got := r.Header.Get("If-None-Match"); got != "" {
+				t.Fatalf("third request If-None-Match = %q, want empty", got)
+			}
+			if got := r.Header.Get("If-Modified-Since"); got != "" {
+				t.Fatalf("third request If-Modified-Since = %q, want empty", got)
+			}
+			_, _ = w.Write([]byte(`third`))
+		default:
+			t.Fatalf("unexpected call count %d", call)
+		}
+	}))
+	defer srv.Close()
+
+	_, _, validators, err := FetchBodyIfChanged(context.Background(), srv.Client(), srv.URL, "test-agent", "", true, HTTPValidators{})
+	if err != nil {
+		t.Fatalf("first FetchBodyIfChanged() error = %v", err)
+	}
+	_, _, validators, err = FetchBodyIfChanged(context.Background(), srv.Client(), srv.URL, "test-agent", "", true, validators)
+	if err != nil {
+		t.Fatalf("second FetchBodyIfChanged() error = %v", err)
+	}
+	if validators.ETag != "" || validators.LastModified != "" {
+		t.Fatalf("validators after 200 without validators = %+v, want cleared", validators)
+	}
+	_, _, _, err = FetchBodyIfChanged(context.Background(), srv.Client(), srv.URL, "test-agent", "", true, validators)
+	if err != nil {
+		t.Fatalf("third FetchBodyIfChanged() error = %v", err)
+	}
+}
+
+func TestFetchBodyIfChangedConditionalDisabledSkipsConditionalHeaders(t *testing.T) {
+	t.Helper()
+
+	var calls int
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		calls++
+		if got := r.Header.Get("If-None-Match"); got != "" {
+			t.Fatalf("request If-None-Match = %q, want empty", got)
+		}
+		if got := r.Header.Get("If-Modified-Since"); got != "" {
+			t.Fatalf("request If-Modified-Since = %q, want empty", got)
+		}
+		_, _ = w.Write([]byte(`body`))
+	}))
+	defer srv.Close()
+
+	validators := HTTPValidators{ETag: `"v1"`, LastModified: "Wed, 04 Jan 2006 15:04:05 GMT"}
+	_, changed, next, err := FetchBodyIfChanged(context.Background(), srv.Client(), srv.URL, "test-agent", "", false, validators)
+	if err != nil {
+		t.Fatalf("FetchBodyIfChanged() error = %v", err)
+	}
+	if !changed {
+		t.Fatalf("FetchBodyIfChanged() changed = false, want true")
+	}
+	if next != validators {
+		t.Fatalf("validators changed when conditional disabled: got %+v want %+v", next, validators)
+	}
+	if calls != 1 {
+		t.Fatalf("calls = %d, want 1", calls)
+	}
+}
+
+func TestFetchBodyIfChangedAllowsEmpty304ButRejectsEmpty200(t *testing.T) {
+	t.Helper()
+
+	notModified := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotModified)
+	}))
+	defer notModified.Close()
+
+	_, changed, _, err := FetchBodyIfChanged(
+		context.Background(),
+		notModified.Client(),
+		notModified.URL,
+		"test-agent",
+		"",
+		true,
+		HTTPValidators{ETag: `"v1"`},
+	)
+	if err != nil {
+		t.Fatalf("304 FetchBodyIfChanged() error = %v", err)
+	}
+	if changed {
+		t.Fatalf("304 FetchBodyIfChanged() changed = true, want false")
+	}
+
+	emptyBody := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer emptyBody.Close()
+
+	_, _, _, err = FetchBodyIfChanged(context.Background(), emptyBody.Client(), emptyBody.URL, "test-agent", "", true, HTTPValidators{})
+	if err == nil {
+		t.Fatalf("empty 200 FetchBodyIfChanged() error = nil, want error")
+	}
+	if err.Error() != "empty response body" {
+		t.Fatalf("empty 200 FetchBodyIfChanged() error = %q", err)
+	}
+}