Replace evidence context with source unit excerpts

2026-08-09 19:42:33 +00:00
parent ad1cba41c2
commit 071a78ae22
10 changed files with 650 additions and 584 deletions
--- a/docs/roadmap/evidence-context.md
+++ b/docs/roadmap/evidence-context.md
@@ -0,0 +1,174 @@
+# Minimal Evidence Context
+
+## Purpose
+
+Redefine the optional `evidence-context.json` output as a compact reading
+excerpt rather than a second provenance model. The artifact should contain the
+smallest useful source projection: the ordered union of source units cited by
+selected accepted lane artifacts, expanded by the configured surrounding
+window.
+
+The normalized lane artifacts remain authoritative for which lane cited which
+source ranges. The original source remains authoritative for the complete
+input. Evidence context is an optional convenience artifact for consumers that
+need the relevant source material alongside the extracted results.
+
+## Motivation
+
+The current artifact repeats source units inside context objects and adds
+context ranges, lane attribution, direct evidence references, source identity,
+source digest, selected lanes, and window configuration. With several lanes
+and a nonzero window, this representation can be substantially larger than the
+complete input by both bytes and tokens. That defeats its intended value as a
+convenient evidence excerpt.
+
+The application already publishes authoritative source references in each
+normalized artifact. Repeating their provenance in `evidence-context.json`
+does not justify the additional size or contract complexity.
+
+## Target Contract
+
+`evidence-context.json` remains an optional pipeline-wide JSON artifact with
+the existing logical filename, artifact kind, media type, schema identity, and
+schema version. Because Notarius is pre-release, the v1 schema may be replaced
+in place and no reader compatibility or migration path is required.
+
+The payload is a top-level JSON array of generic source units. It has no
+evidence-context-specific wrapper or metadata. Every element uses the existing
+`source.SourceUnit` representation and therefore preserves its required
+`id`, `kind`, `text`, and self-reference together with any metadata already
+owned by the source unit. “No additional metadata” means that evidence-context
+construction does not annotate, reshape, or enrich a source unit; it does not
+mean stripping metadata supplied by the input adapter.
+
+An enabled output with no accepted cited evidence emits `[]`, not `null` and
+not an absent artifact. The artifact remains absent when evidence-context
+publication is not enabled.
+
+## Selection Semantics
+
+Construction must:
+
+1. obtain source references only through the typed evidence projections of
+   accepted normalized outputs from the configured lane allowlist;
+2. validate every projected reference against the current source document;
+3. expand each valid referenced range by `window_units` positions on both
+   sides, clamping at the source boundaries;
+4. take the union of all expanded ranges;
+5. emit every selected source unit exactly once and in source-document
+   position order; and
+6. return owned copies so later mutation cannot alias the source document or
+   output artifact.
+
+Overlapping and adjacent ranges may be coalesced internally, but range groups
+are not represented in the payload. Repeated citations, citations from
+multiple lanes, and overlapping windows never duplicate a source unit.
+Rejected, failed, absent, inactive, and unselected lanes contribute nothing.
+
+The selected set is therefore bounded by the source document: it can contain
+at most every source unit once. With broad evidence coverage or a sufficiently
+large window, it may legitimately equal the complete generic source document.
+No byte- or token-size guarantee is made because generic source-unit
+serialization can differ from the external input format and output formatting
+has its own overhead. The application must not truncate a complete excerpt to
+meet an arbitrary size limit.
+
+## Configuration And Publication
+
+Retain the current `output.options.evidence_context` configuration:
+
+- `enabled` continues to control publication;
+- `lanes` remains the non-empty allowlist of configured artifact lanes whose
+  accepted normalized evidence contributes to the excerpt; and
+- `window_units` remains a non-negative optional value with the existing
+  default of three.
+
+Retain `evidence-context.json` and the pipeline-wide `index.json`
+`evidence_context` descriptor. The descriptor remains the canonical place for
+artifact identity and discovery. It must not be copied into the payload.
+
+## Internal Design
+
+Keep evidence preparation at the current framework and output boundary. The
+generic framework should continue to consume typed evidence projections rather
+than inspect domain JSON or import domain artifact types.
+
+Simplify `internal/framework/evidencecontext` around the new contract:
+
+- represent the durable document as a collection of source units rather than
+  contexts and evidence contributions;
+- reduce the build request to the source document, window size, and projected
+  source references needed to select units;
+- remove durable and internal types used only for lane attribution, context
+  ranges, and evidence-reference publication;
+- retain strict schema validation, deterministic serialization, source and
+  reference validation, ownership, and stable artifact identity; and
+- preserve the existing pipeline preparation logic that validates configured
+  lanes and typed evidence projections.
+
+The pipeline may continue to record a content-free debug summary containing
+artifact identity, selected lane configuration, window size, source digest,
+and emitted unit count. Remove the obsolete context count. Debug information
+is operational state outside `evidence-context.json` and must not contain the
+selected source text or source-unit metadata.
+
+## Documentation Impact
+
+When the implementation lands, rewrite the durable contract in
+`docs/integrations/evidence-context.md`. Update the configuration, JSON-output,
+subprocess-consumer, operations, and internal-module documentation wherever it
+describes the old context or provenance structure. Preserve canonical
+ownership: the integration contract defines the payload; other documents give
+only the information appropriate to their audience and link to that contract.
+
+The maintained complete D&D configuration should retain its existing evidence
+publication settings. No new example is needed because the configuration
+surface is unchanged.
+
+## Testing Expectations
+
+Tests should protect the revised behavior rather than the former internal
+shape. At the narrowest stable boundaries, verify:
+
+- window expansion and source-boundary clamping;
+- union, deduplication, and source-position ordering, including non-monotonic
+  unit IDs;
+- unchanged source-unit values and owned metadata;
+- `[]` for enabled publication with no accepted cited evidence;
+- rejection of invalid sources, references, and durable payloads;
+- omission when publication is disabled;
+- contribution only from selected accepted normalized outputs, including
+  checkpoint reconstruction; and
+- correct JSON bundle publication and index discovery.
+
+Do not add an exact byte-length, token-count, or ratio test. Such a test would
+be format-sensitive and would not protect the durable contract. The meaningful
+boundedness invariant is structural: every emitted element corresponds to one
+distinct unit from the source document, and no source unit is emitted more
+than once.
+
+## Documentation Decision
+
+No new ADR is required. This work simplifies a pre-release output contract but
+does not change the architectural ownership of source evidence, typed
+projections, pipeline stages, or output publication. The durable contract and
+current implementation documentation should be updated when the behavior is
+implemented; this roadmap owns the proposed behavior until then.
+
+## Acceptance Criteria
+
+- `evidence-context.json` is a top-level array containing only selected generic
+  source units.
+- The payload contains no context groups, lane IDs, evidence references,
+  source-level wrapper fields, or evidence-context-specific annotations.
+- Units are copied unchanged from the source document, appear once, and retain
+  source-document order.
+- Existing lane selection and `window_units` behavior remain configurable and
+  retain their current validation and defaults.
+- The artifact remains optional, keeps its filename and identity, and remains
+  discoverable through `index.json`.
+- The implementation retains strict validation, deterministic output,
+  ownership, failure propagation, checkpoint behavior, and content-free debug
+  reporting.
+- Current documentation and maintained examples accurately describe the new
+  contract, and the repository-wide tests, vet, and build pass.
--- a/docs/roadmap/implementation.md
+++ b/docs/roadmap/implementation.md
@@ -0,0 +1,315 @@
+# Minimal Evidence Context Implementation Plan
+
+## Objective
+
+Implement the target state defined in
+[Minimal Evidence Context](evidence-context.md): retain the optional
+`evidence-context.json` output and its existing configuration while replacing
+its provenance-heavy payload with the ordered, deduplicated union of selected
+generic source units.
+
+This plan intentionally changes the existing v1 contract in place. Notarius is
+pre-release, so do not add legacy decoding, schema-version branching,
+migration, dual publication, or other backward-compatibility machinery.
+
+## Global Implementation Rules
+
+Apply these rules in every stage:
+
+- Follow `docs/policy/architecture.md`, `docs/policy/documentation.md`, and
+  `docs/policy/testing.md`.
+- Treat the normalized lane artifacts as authoritative for citations and the
+  source document as authoritative for source-unit content.
+- Preserve the typed evidence-projection boundary. Generic code must not
+  inspect domain JSON or depend on D&D artifact types.
+- Preserve the logical filename `evidence-context.json`, artifact kind
+  `source/evidence-context`, media type `application/json`, schema ID
+  `notarius.source.evidence_context`, schema name
+  `notarius_source_evidence_context_v1`, and schema version `v1`.
+- Preserve the current configuration keys, validation, lane allowlist
+  semantics, and default `window_units` value.
+- Do not introduce a payload wrapper. The durable JSON value is a top-level
+  array of generic source units; the empty value is `[]`.
+- Preserve source-unit fields and metadata exactly as represented in the
+  validated generic source document. Add no evidence-context-specific fields.
+- Do not add byte-count, token-count, or compression-ratio tests. Test the
+  structural boundedness and behavioral contract instead.
+- Use focused tests while iterating and leave the repository compiling and its
+  relevant test suites passing at the end of every stage.
+
+## Stage 1: Replace The Core Evidence-Context Contract
+
+### Goal
+
+Replace the context/provenance model with a strict top-level source-unit array
+and simplify construction to select the union of expanded source ranges.
+
+### Required Changes
+
+1. Update `internal/framework/evidencecontext/model.go`:
+   - represent `Document` as the durable collection of `source.SourceUnit`
+     values that serializes directly as a JSON array;
+   - retain the existing artifact identity constants;
+   - reduce `BuildRequest` to `Source`, `WindowUnits`, and a flat collection of
+     projected `SourceRefs`;
+   - remove `Context`, `EvidenceRef`, `LaneEvidence`, and any other types whose
+     only purpose was durable lane attribution or context grouping.
+2. Update `internal/framework/evidencecontext/build.go`:
+   - validate the window and complete source document, including its digest;
+   - validate every projected source reference against the source index;
+   - convert referenced endpoints to source positions, expand and clamp them,
+     and merge their union;
+   - append owned copies of the selected source units once in document-position
+     order;
+   - return an initialized empty document when there are no references;
+   - remove sorting keys and helpers that exist only to order lane attribution
+     or evidence records.
+3. Update `internal/framework/evidencecontext/codec.go` and
+   `internal/framework/evidencecontext/assets/schemas/source_evidence_context.v1.json`:
+   - define the root schema as an array of strict source-unit objects;
+   - preserve the existing source-unit contract: required `id`, `kind`, `text`,
+     and `ref`, with optional open-ended source-owned `metadata`;
+   - ensure decode rejects `null`, wrapper objects, malformed units, unknown
+     fixed unit/reference fields, invalid self-references, and noncanonical
+     documents;
+   - ensure encode and decode own all slice and nested metadata values and
+     serialize an empty document as `[]`;
+   - remove canonicalization logic used only by the deleted wrapper and context
+     structures.
+4. Replace the fixture in
+   `internal/framework/evidencecontext/testdata/source_evidence_context.v1.json`
+   with a compact top-level unit array.
+5. Rewrite `internal/framework/evidencecontext/evidencecontext_test.go` around
+   durable behavior:
+   - cover expanded overlapping and adjacent ranges, boundary clamping,
+     repeated references, and non-monotonic unit IDs;
+   - prove that the output is source-ordered, contains each selected source
+     unit once, and never invents a unit;
+   - prove preservation and ownership of source-unit metadata;
+   - cover empty-array encoding and strict invalid-input rejection;
+   - retain artifact identity and deterministic round-trip coverage without
+     testing deleted internal structures.
+6. Adapt `internal/framework/pipeline/evidence_output.go` so it flattens the
+   typed references from prepared selected lanes into the new build request.
+   Preserve all existing checks for duplicate accepted lane outputs, source and
+   artifact-kind compatibility, codec decoding, and evidence projection
+   failures.
+7. Adapt the pipeline debug summary and its use in `runner.go` as necessary:
+   - calculate selected lanes, window size, and source digest from the prepared
+     plan and source document rather than the payload;
+   - report the emitted unit count directly;
+   - remove `context_count`;
+   - keep source text and unit metadata out of debug summaries.
+8. Rewrite the focused tests in
+   `internal/framework/pipeline/evidence_output_test.go` to assert the new
+   payload while preserving coverage of selected accepted outputs, absent and
+   rejected lanes, incompatible artifacts, failure propagation, ownership,
+   checkpoint reconstruction, opt-in behavior, and redacted debug reporting.
+
+### Acceptance Criteria
+
+- The evidence-context package has no durable or internal model for context
+  groups, lane attribution, or published evidence references.
+- Its codec accepts and emits only the new top-level array contract.
+- Its builder returns the exact ordered union of source units selected by the
+  expanded validated ranges.
+- Pipeline construction still obtains references exclusively through prepared
+  typed evidence projections.
+- The payload remains absent when publication is not configured and is `[]`
+  when enabled with no contributing evidence.
+- Focused framework tests pass.
+
+### Validation
+
+```sh
+gofmt -w internal/framework/evidencecontext internal/framework/pipeline/evidence_output.go internal/framework/pipeline/evidence_output_test.go
+go test ./internal/framework/evidencecontext ./internal/framework/pipeline
+```
+
+### Prompt Scope
+
+This is one coherent but substantial gpt-5.6-terra prompt. Keep the work
+limited to the core contract, its pipeline construction boundary, and their
+focused tests; do not update generic JSON output tests, production integration
+tests, or documentation in this stage.
+
+## Stage 2: Update Output And Production Integration Coverage
+
+### Goal
+
+Carry the revised artifact through the generic JSON output and representative
+assembled D&D workflows without changing publication or discovery semantics.
+
+### Required Changes
+
+1. Review `internal/modules/generic/output/json/encoder.go` and retain the
+   existing option decoding, default window, lane validation, logical filename,
+   artifact identity checks, pretty JSON publication, and `index.json`
+   descriptor. Change production code only where it assumes the old payload.
+2. Rewrite evidence-context fixtures and assertions in
+   `internal/modules/generic/output/json/encoder_test.go`:
+   - validate and publish a top-level unit array;
+   - retain descriptor, omission, strict artifact validation, and
+     content-nondisclosure failure tests;
+   - remove expectations for wrapper fields or contexts.
+3. Update evidence assertions in the representative integration and CLI
+   contract tests, including:
+   - `internal/modules/integration/dnd_npc_grounded_test.go`;
+   - `internal/modules/integration/dnd_location_registry_runner_test.go`;
+   - `internal/cli/dnd_enemy_events_contract_test.go`; and
+   - any additional test located by searching for `evidence-context`,
+     `EvidenceContext`, `Contexts`, `context_count`, or old fixture fields.
+4. Ensure the integration assertions protect the behavior that matters:
+   - only selected accepted lanes contribute references;
+   - multiple lanes and overlapping windows produce one ordered unit union;
+   - non-monotonic unit IDs do not change source-position order;
+   - scene-description selection remains explicit;
+   - the output descriptor remains pipeline-wide rather than a lane artifact.
+5. Remove obsolete helpers and fixtures that only inspect old context groups or
+   per-lane evidence records. Do not preserve compatibility helpers.
+
+### Acceptance Criteria
+
+- The generic JSON encoder publishes the new payload under the existing
+  filename and descriptor.
+- Maintained integration and CLI workflows observe a deduplicated array of
+  unchanged source units.
+- No production code or test outside the archived roadmap refers to deleted
+  payload fields or types.
+- Focused output, integration, and CLI tests pass.
+
+### Validation
+
+```sh
+gofmt -w internal/modules/generic/output/json internal/modules/integration internal/cli
+go test ./internal/modules/generic/output/json ./internal/modules/integration ./internal/cli
+rg -n 'context_ref|evidence_refs|selected_lanes|source_digest|context_count|\.Contexts\b' internal --glob '*.go' --glob '*.json'
+```
+
+Review every remaining search result rather than requiring the search to be
+empty: `source_digest` and similar terms are valid in unrelated contracts and
+content-free debug state.
+
+### Prompt Scope
+
+This stage is appropriately sized for one gpt-5.6-terra prompt. It owns output
+and assembled-workflow adaptation only; do not revise public documentation in
+this stage.
+
+## Stage 3: Rewrite The Canonical Documentation
+
+### Goal
+
+Make all current documentation describe the implemented minimal evidence
+excerpt, with the durable contract defined in one canonical location.
+
+### Required Changes
+
+1. Rewrite `docs/integrations/evidence-context.md` as the canonical durable
+   contract:
+   - retain identity, discovery, filename, and optionality;
+   - define the top-level source-unit array and empty-array behavior;
+   - define typed-evidence selection, window expansion, union, deduplication,
+     source-position ordering, and unchanged-unit semantics;
+   - state that the excerpt can include at most every generic source unit once
+     but has no byte/token-size guarantee;
+   - state that lane artifacts remain authoritative for citations and the
+     excerpt contains no lane attribution;
+   - preserve sensitivity and consumer validation guidance.
+2. Update `docs/config.md` only where it describes the result of
+   `evidence_context`. Preserve the existing keys, validation rules, and default
+   window. Link to the integration contract for payload details.
+3. Update `docs/integrations/json-output.md` to describe the logical file as the
+   optional selected source-unit excerpt without duplicating its schema.
+4. Update `docs/consumers/subprocess.md` so consumers decode the array and use
+   lane artifacts—not the excerpt—for authoritative citations and lane
+   provenance.
+5. Update `docs/operations.md`, `docs/internal/modules.md`, and any other current
+   documentation that describes context groups, provenance records, or the old
+   wrapper. Keep operational sensitivity guidance and internal ownership in
+   their canonical documents.
+6. Review `examples/dnd-complete.config.yml`. Retain the current
+   `evidence_context` configuration and lane list unless repository inspection
+   reveals an independently stale module key. Do not add a new example solely
+   for this unchanged configuration surface.
+7. Do not modify ADRs or add a new ADR. Do not rewrite archived audit history
+   to match current behavior.
+
+### Acceptance Criteria
+
+- `docs/integrations/evidence-context.md` is the sole canonical definition of
+  the payload.
+- Other current documents accurately summarize their audience-specific aspect
+  and link to the contract instead of duplicating it.
+- No current documentation claims that `evidence-context.json` contains
+  context groups, evidence-reference records, lane attribution, source-level
+  wrapper metadata, or a guaranteed byte/token reduction.
+- The maintained complete example remains valid and reflects implemented
+  configuration.
+
+### Validation
+
+```sh
+rg -n 'context_ref|evidence_refs|selected_lanes|context_count' README.md docs examples --glob '!docs/roadmap/**' --glob '!docs/adr/**'
+go test ./internal/config ./internal/modules/generic/output/json ./internal/cli
+```
+
+Inspect any search matches for legitimate historical or unrelated use. If the
+repository provides no automated Markdown link checker, manually verify every
+link changed in this stage.
+
+### Prompt Scope
+
+This documentation migration is small enough for one gpt-5.6-terra prompt.
+
+## Stage 4: Final Verification And Cleanup
+
+### Goal
+
+Verify the complete feature across package, integration, documentation, and
+repository boundaries, then remove only obsolete implementation debris found
+by that verification.
+
+### Required Changes
+
+1. Review the diff against `docs/roadmap/evidence-context.md` and confirm every
+   acceptance criterion is implemented.
+2. Search the non-archived repository for deleted Go types, old JSON fields,
+   obsolete fixture shapes, and statements that describe the former contract.
+3. Confirm the schema, codec, builder, pipeline request, debug summary, output
+   encoder, index descriptor, example configuration, and integration contract
+   agree on the final shape and identities.
+4. Run formatting and the complete offline validation suite.
+5. Make only narrowly scoped corrections required by failed checks or direct
+   roadmap divergence. Do not introduce unrelated refactors or new features.
+6. Leave the active roadmap documents in place for post-implementation review;
+   retirement occurs only when separately requested after the implementation
+   is accepted.
+
+### Acceptance Criteria
+
+- All roadmap acceptance criteria are satisfied with no legacy compatibility
+  path.
+- No current code, schema, fixture, example, or documentation depends on the
+  former wrapper/context/provenance payload.
+- The structural bound is protected: the artifact contains only distinct,
+  unchanged units from the source document in source order.
+- Repository formatting, tests, vet, and build all pass.
+- The worktree contains only intentional feature changes.
+
+### Validation
+
+```sh
+gofmt -w internal/framework/evidencecontext internal/framework/pipeline internal/modules/generic/output/json internal/modules/integration internal/cli
+go test ./...
+go vet ./...
+go build ./cmd/notarius
+git diff --check
+git status --short
+```
+
+### Prompt Scope
+
+This verification pass is small enough for one gpt-5.6-terra prompt. If it
+uncovers a material unrelated defect, report it separately instead of widening
+this feature.
--- a/internal/framework/evidencecontext/assets/schemas/source_evidence_context.v1.json
+++ b/internal/framework/evidencecontext/assets/schemas/source_evidence_context.v1.json
@@ -2,24 +2,8 @@
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "notarius.source.evidence_context",
  "title": "notarius_source_evidence_context_v1",
-  "type": "object",
-  "additionalProperties": false,
-  "required": ["source_id", "source_digest", "window_units", "selected_lanes", "contexts"],
-  "properties": {
-    "source_id": {"type": "string", "minLength": 1},
-    "source_digest": {"type": "string", "pattern": "^sha256:[0-9a-f]{64}$"},
-    "window_units": {"type": "integer", "minimum": 0},
-    "selected_lanes": {
-      "type": "array",
-      "minItems": 1,
-      "uniqueItems": true,
-      "items": {"type": "string", "minLength": 1}
-    },
-    "contexts": {
-      "type": "array",
-      "items": {"$ref": "#/$defs/context"}
-    }
-  },
+  "type": "array",
+  "items": {"$ref": "#/$defs/unit"},
  "$defs": {
    "source_ref": {
      "type": "object",
@@ -42,25 +26,6 @@
        "ref": {"$ref": "#/$defs/source_ref"},
        "metadata": {"type": "object", "additionalProperties": true}
      }
-    },
-    "evidence_ref": {
-      "type": "object",
-      "additionalProperties": false,
-      "required": ["lane_id", "source_ref"],
-      "properties": {
-        "lane_id": {"type": "string", "minLength": 1},
-        "source_ref": {"$ref": "#/$defs/source_ref"}
-      }
-    },
-    "context": {
-      "type": "object",
-      "additionalProperties": false,
-      "required": ["context_ref", "evidence_refs", "units"],
-      "properties": {
-        "context_ref": {"$ref": "#/$defs/source_ref"},
-        "evidence_refs": {"type": "array", "minItems": 1, "items": {"$ref": "#/$defs/evidence_ref"}},
-        "units": {"type": "array", "minItems": 1, "items": {"$ref": "#/$defs/unit"}}
-      }
    }
  }
 }
--- a/internal/framework/evidencecontext/build.go
+++ b/internal/framework/evidencecontext/build.go
@@ -3,118 +3,58 @@ package evidencecontext
 import (
 	"fmt"
 	"sort"
-	"strings"

 	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
 )

-type contribution struct {
-	laneID   string
-	ref      source.SourceRef
+type expandedRange struct {
 	startPos int
 	endPos   int
 }

-type expandedRange struct {
-	startPos      int
-	endPos        int
-	contributions []contribution
-}
-
-// Build validates accepted direct references, expands them by source-document
-// position, and returns their deterministic context union.
+// Build validates projected source references, expands them by source-document
+// position, and returns their ordered union as an owned source-unit excerpt.
 func Build(request BuildRequest) (Document, error) {
 	if request.WindowUnits < 0 {
-		return Document{}, fmt.Errorf("window_units must not be negative")
-	}
-	lanes, err := normalizeSelectedLanes(request.SelectedLanes)
-	if err != nil {
-		return Document{}, err
+		return nil, fmt.Errorf("window_units must not be negative")
 	}
 	if err := source.ValidateDocument(request.Source); err != nil {
-		return Document{}, fmt.Errorf("validate source document: %w", err)
+		return nil, fmt.Errorf("validate source document: %w", err)
 	}
 	digest, err := source.DigestDocument(request.Source)
 	if err != nil {
-		return Document{}, fmt.Errorf("digest source document: %w", err)
+		return nil, fmt.Errorf("digest source document: %w", err)
 	}
 	if digest != request.Source.Digest {
-		return Document{}, fmt.Errorf("source digest does not match source document digest")
+		return nil, fmt.Errorf("source digest does not match source document digest")
 	}

-	selected := make(map[string]struct{}, len(lanes))
-	for _, laneID := range lanes {
-		selected[laneID] = struct{}{}
-	}
 	index := source.NewDocumentIndex(request.Source)
-	seen := make(map[evidenceKey]struct{})
-	contributions := make([]contribution, 0)
-	for laneIndex, laneEvidence := range request.LaneEvidence {
-		laneID := strings.TrimSpace(laneEvidence.LaneID)
-		if _, ok := selected[laneID]; !ok {
-			return Document{}, fmt.Errorf("lane evidence[%d] lane %q is not selected", laneIndex, laneID)
+	ranges := make([]expandedRange, 0, len(request.SourceRefs))
+	for refIndex, ref := range request.SourceRefs {
+		if err := index.ValidateRef(ref); err != nil {
+			return nil, fmt.Errorf("source reference[%d]: %w", refIndex, err)
 		}
-		for refIndex, ref := range laneEvidence.SourceRefs {
-			if err := index.ValidateRef(ref); err != nil {
-				return Document{}, fmt.Errorf("lane %q source reference[%d]: %w", laneID, refIndex, err)
+		startPos, _ := index.Position(ref.StartUnitID)
+		endPos, _ := index.Position(ref.EndUnitID)
+		ranges = append(ranges, expandedRange{
+			startPos: expandStart(startPos, request.WindowUnits),
+			endPos:   expandEnd(endPos, len(request.Source.Units), request.WindowUnits),
+		})
+	}
+
+	merged := mergeRanges(ranges)
+	document := make(Document, 0)
+	for _, value := range merged {
+		for position := value.startPos; position <= value.endPos; position++ {
+			unit, err := cloneSourceUnit(request.Source.Units[position])
+			if err != nil {
+				return nil, fmt.Errorf("clone source unit at position %d: %w", position, err)
 			}
-			key := evidenceKey{laneID: laneID, ref: ref}
-			if _, exists := seen[key]; exists {
-				continue
-			}
-			seen[key] = struct{}{}
-			startPos, _ := index.Position(ref.StartUnitID)
-			endPos, _ := index.Position(ref.EndUnitID)
-			contributions = append(contributions, contribution{laneID: laneID, ref: ref, startPos: expandStart(startPos, request.WindowUnits), endPos: expandEnd(endPos, len(request.Source.Units), request.WindowUnits)})
+			document = append(document, unit)
 		}
 	}
-
-	sort.Slice(contributions, func(i, j int) bool { return lessContribution(contributions[i], contributions[j]) })
-	document := Document{
-		SourceID:      request.Source.ID,
-		SourceDigest:  digest,
-		WindowUnits:   request.WindowUnits,
-		SelectedLanes: lanes,
-		Contexts:      make([]Context, 0),
-	}
-	for _, rangeValue := range mergeRanges(contributions) {
-		context, err := buildContext(request.Source, rangeValue)
-		if err != nil {
-			return Document{}, err
-		}
-		document.Contexts = append(document.Contexts, context)
-	}
-	canonical, err := canonicalizeOwned(document)
-	if err != nil {
-		return Document{}, fmt.Errorf("validate evidence context: %w", err)
-	}
-	return canonical, nil
-}
-
-type evidenceKey struct {
-	laneID string
-	ref    source.SourceRef
-}
-
-func normalizeSelectedLanes(values []string) ([]string, error) {
-	if len(values) == 0 {
-		return nil, fmt.Errorf("selected_lanes must not be empty")
-	}
-	seen := make(map[string]struct{}, len(values))
-	lanes := make([]string, 0, len(values))
-	for index, raw := range values {
-		laneID := strings.TrimSpace(raw)
-		if laneID == "" {
-			return nil, fmt.Errorf("selected_lanes[%d] must not be empty", index)
-		}
-		if _, exists := seen[laneID]; exists {
-			return nil, fmt.Errorf("selected_lanes lane %q is duplicated", laneID)
-		}
-		seen[laneID] = struct{}{}
-		lanes = append(lanes, laneID)
-	}
-	sort.Strings(lanes)
-	return lanes, nil
+	return document, nil
 }

 func expandStart(position, window int) int {
@@ -132,65 +72,25 @@ func expandEnd(position, length, window int) int {
 	return position + window
 }

-func lessContribution(left, right contribution) bool {
-	if left.startPos != right.startPos {
-		return left.startPos < right.startPos
-	}
-	if left.endPos != right.endPos {
-		return left.endPos < right.endPos
-	}
-	return lessEvidenceRef(EvidenceRef{LaneID: left.laneID, SourceRef: left.ref}, EvidenceRef{LaneID: right.laneID, SourceRef: right.ref})
-}
-
-func mergeRanges(values []contribution) []expandedRange {
+func mergeRanges(values []expandedRange) []expandedRange {
 	if len(values) == 0 {
 		return nil
 	}
-	ranges := make([]expandedRange, 0, len(values))
+	sort.Slice(values, func(i, j int) bool {
+		if values[i].startPos != values[j].startPos {
+			return values[i].startPos < values[j].startPos
+		}
+		return values[i].endPos < values[j].endPos
+	})
+	merged := make([]expandedRange, 0, len(values))
 	for _, value := range values {
-		if len(ranges) == 0 || value.startPos > ranges[len(ranges)-1].endPos+1 {
-			ranges = append(ranges, expandedRange{startPos: value.startPos, endPos: value.endPos, contributions: []contribution{value}})
+		if len(merged) == 0 || value.startPos > merged[len(merged)-1].endPos+1 {
+			merged = append(merged, value)
 			continue
 		}
-		current := &ranges[len(ranges)-1]
-		if value.endPos > current.endPos {
-			current.endPos = value.endPos
+		if value.endPos > merged[len(merged)-1].endPos {
+			merged[len(merged)-1].endPos = value.endPos
 		}
-		current.contributions = append(current.contributions, value)
 	}
-	return ranges
-}
-
-func buildContext(document *source.SourceDocument, value expandedRange) (Context, error) {
-	evidenceRefs := make([]EvidenceRef, 0, len(value.contributions))
-	for _, contribution := range value.contributions {
-		evidenceRefs = append(evidenceRefs, EvidenceRef{LaneID: contribution.laneID, SourceRef: contribution.ref})
-	}
-	sort.Slice(evidenceRefs, func(i, j int) bool { return lessEvidenceRef(evidenceRefs[i], evidenceRefs[j]) })
-	units := make([]source.SourceUnit, 0, value.endPos-value.startPos+1)
-	for position := value.startPos; position <= value.endPos; position++ {
-		unit, err := cloneSourceUnit(document.Units[position])
-		if err != nil {
-			return Context{}, fmt.Errorf("clone source unit at position %d: %w", position, err)
-		}
-		units = append(units, unit)
-	}
-	return Context{
-		ContextRef:   source.SourceRef{SourceID: document.ID, StartUnitID: units[0].ID, EndUnitID: units[len(units)-1].ID},
-		EvidenceRefs: evidenceRefs,
-		Units:        units,
-	}, nil
-}
-
-func lessEvidenceRef(left, right EvidenceRef) bool {
-	if left.LaneID != right.LaneID {
-		return left.LaneID < right.LaneID
-	}
-	if left.SourceRef.SourceID != right.SourceRef.SourceID {
-		return left.SourceRef.SourceID < right.SourceRef.SourceID
-	}
-	if left.SourceRef.StartUnitID != right.SourceRef.StartUnitID {
-		return left.SourceRef.StartUnitID < right.SourceRef.StartUnitID
-	}
-	return left.SourceRef.EndUnitID < right.SourceRef.EndUnitID
+	return merged
 }
--- a/internal/framework/evidencecontext/codec.go
+++ b/internal/framework/evidencecontext/codec.go
@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"regexp"
 	"strings"
 	"sync"

@@ -18,8 +17,6 @@ import (
 //go:embed assets/schemas/source_evidence_context.v1.json
 var schemaAssets embed.FS

-var digestPattern = regexp.MustCompile(`^sha256:[0-9a-f]{64}$`)
-
 var (
 	loadSchemaOnce sync.Once
 	loadedSchema   []byte
@@ -78,24 +75,24 @@ func (c *Codec) Encode(value Document) ([]byte, error) {

 func (c *Codec) Decode(content []byte) (Document, error) {
 	if _, err := c.schemaBytes(); err != nil {
-		return Document{}, err
+		return nil, err
 	}
 	if err := validateSchemaInstance(content); err != nil {
-		return Document{}, fmt.Errorf("decode evidence context: %w", err)
+		return nil, fmt.Errorf("decode evidence context: %w", err)
 	}
 	decoder := json.NewDecoder(bytes.NewReader(content))
 	decoder.DisallowUnknownFields()
 	var value Document
 	if err := decoder.Decode(&value); err != nil {
-		return Document{}, fmt.Errorf("decode evidence context: %w", err)
+		return nil, fmt.Errorf("decode evidence context: %w", err)
 	}
 	var trailing any
 	if err := decoder.Decode(&trailing); err != io.EOF {
-		return Document{}, fmt.Errorf("decode evidence context: multiple JSON values")
+		return nil, fmt.Errorf("decode evidence context: multiple JSON values")
 	}
 	canonical, err := canonicalizeOwned(value)
 	if err != nil {
-		return Document{}, fmt.Errorf("decode evidence context: %w", err)
+		return nil, fmt.Errorf("decode evidence context: %w", err)
 	}
 	return canonical, nil
 }
@@ -115,17 +112,16 @@ func loadAndCompileSchema() {
 		return
 	}
 	var identity struct {
-		ID       string   `json:"$id"`
-		Title    string   `json:"title"`
-		Type     string   `json:"type"`
-		Required []string `json:"required"`
+		ID    string `json:"$id"`
+		Title string `json:"title"`
+		Type  string `json:"type"`
 	}
 	if err := json.Unmarshal(raw, &identity); err != nil {
 		loadSchemaErr = fmt.Errorf("decode source evidence context schema: %w", err)
 		return
 	}
-	if identity.ID != SchemaID || identity.Title != SchemaName || identity.Type != "object" || !hasRequiredFields(identity.Required) {
-		loadSchemaErr = fmt.Errorf("source evidence context schema identity or required fields are invalid")
+	if identity.ID != SchemaID || identity.Title != SchemaName || identity.Type != "array" {
+		loadSchemaErr = fmt.Errorf("source evidence context schema identity is invalid")
 		return
 	}
 	schemaDocument, err := jsonschema.UnmarshalJSON(bytes.NewReader(raw))
@@ -158,164 +154,59 @@ func validateSchemaInstance(content []byte) error {
 	return nil
 }

-func hasRequiredFields(required []string) bool {
-	want := map[string]bool{"source_id": true, "source_digest": true, "window_units": true, "selected_lanes": true, "contexts": true}
-	for _, field := range required {
-		delete(want, field)
-	}
-	return len(want) == 0
-}
-
 func canonicalize(value Document) (Document, error) {
 	owned, err := clone(value)
 	if err != nil {
-		return Document{}, err
+		return nil, err
 	}
 	return canonicalizeOwned(owned)
 }

 func canonicalizeOwned(value Document) (Document, error) {
-	if err := requireIdentity("source_id", value.SourceID); err != nil {
-		return Document{}, err
+	if value == nil {
+		return nil, fmt.Errorf("document must be a JSON array")
 	}
-	if !digestPattern.MatchString(value.SourceDigest) {
-		return Document{}, fmt.Errorf("source_digest must be a sha256 digest")
-	}
-	if value.WindowUnits < 0 {
-		return Document{}, fmt.Errorf("window_units must not be negative")
-	}
-	if err := validateSelectedLanes(value.SelectedLanes); err != nil {
-		return Document{}, err
-	}
-	if value.Contexts == nil {
-		value.Contexts = make([]Context, 0)
-	}
-	selected := make(map[string]struct{}, len(value.SelectedLanes))
-	for _, laneID := range value.SelectedLanes {
-		selected[laneID] = struct{}{}
-	}
-	seenUnits := make(map[int]struct{})
-	for contextIndex := range value.Contexts {
-		context, err := canonicalizeContext(value.SourceID, selected, seenUnits, value.Contexts[contextIndex], contextIndex)
-		if err != nil {
-			return Document{}, err
-		}
-		value.Contexts[contextIndex] = context
-	}
-	return value, nil
-}
-
-func validateSelectedLanes(lanes []string) error {
-	if len(lanes) == 0 {
-		return fmt.Errorf("selected_lanes must not be empty")
-	}
-	for index, laneID := range lanes {
-		if err := requireIdentity(fmt.Sprintf("selected_lanes[%d]", index), laneID); err != nil {
-			return err
-		}
-		if index > 0 && lanes[index-1] >= laneID {
-			return fmt.Errorf("selected_lanes must be unique and in lexical order")
-		}
-	}
-	return nil
-}
-
-func canonicalizeContext(sourceID string, selected map[string]struct{}, seenUnits map[int]struct{}, value Context, contextIndex int) (Context, error) {
-	prefix := fmt.Sprintf("contexts[%d]", contextIndex)
-	if len(value.EvidenceRefs) == 0 {
-		return Context{}, fmt.Errorf("%s.evidence_refs must not be empty", prefix)
-	}
-	if len(value.Units) == 0 {
-		return Context{}, fmt.Errorf("%s.units must not be empty", prefix)
-	}
-	if err := validateRefIdentity(sourceID, value.ContextRef, prefix+".context_ref"); err != nil {
-		return Context{}, err
-	}
-	positions := make(map[int]int, len(value.Units))
-	for unitIndex := range value.Units {
-		unit := value.Units[unitIndex]
+	seenUnitIDs := make(map[int]struct{}, len(value))
+	for unitIndex := range value {
+		unit := value[unitIndex]
 		if unit.ID <= 0 || strings.TrimSpace(unit.Kind) == "" || strings.TrimSpace(unit.Text) == "" {
-			return Context{}, fmt.Errorf("%s.units[%d] has invalid required fields", prefix, unitIndex)
+			return nil, fmt.Errorf("units[%d] has invalid required fields", unitIndex)
 		}
-		if err := validateRefIdentity(sourceID, unit.Ref, fmt.Sprintf("%s.units[%d].ref", prefix, unitIndex)); err != nil {
-			return Context{}, err
+		if err := validateUnitRef(unit, unitIndex); err != nil {
+			return nil, err
 		}
-		if unit.Ref.StartUnitID != unit.ID || unit.Ref.EndUnitID != unit.ID {
-			return Context{}, fmt.Errorf("%s.units[%d].ref must identify unit id %d", prefix, unitIndex, unit.ID)
-		}
-		if _, exists := positions[unit.ID]; exists {
-			return Context{}, fmt.Errorf("%s.units contains duplicate unit id %d", prefix, unit.ID)
-		}
-		if _, exists := seenUnits[unit.ID]; exists {
-			return Context{}, fmt.Errorf("contexts contain duplicate unit id %d", unit.ID)
-		}
-		positions[unit.ID] = unitIndex
-		seenUnits[unit.ID] = struct{}{}
-	}
-	if value.ContextRef.StartUnitID != value.Units[0].ID || value.ContextRef.EndUnitID != value.Units[len(value.Units)-1].ID {
-		return Context{}, fmt.Errorf("%s.context_ref must identify the first and last units", prefix)
-	}
-	for evidenceIndex := range value.EvidenceRefs {
-		evidence := value.EvidenceRefs[evidenceIndex]
-		if _, ok := selected[evidence.LaneID]; !ok {
-			return Context{}, fmt.Errorf("%s.evidence_refs[%d].lane_id is not selected", prefix, evidenceIndex)
-		}
-		if err := requireIdentity(fmt.Sprintf("%s.evidence_refs[%d].lane_id", prefix, evidenceIndex), evidence.LaneID); err != nil {
-			return Context{}, err
-		}
-		if err := validateRefIdentity(sourceID, evidence.SourceRef, fmt.Sprintf("%s.evidence_refs[%d].source_ref", prefix, evidenceIndex)); err != nil {
-			return Context{}, err
-		}
-		start, startOK := positions[evidence.SourceRef.StartUnitID]
-		end, endOK := positions[evidence.SourceRef.EndUnitID]
-		if !startOK || !endOK || start > end {
-			return Context{}, fmt.Errorf("%s.evidence_refs[%d].source_ref is outside context units", prefix, evidenceIndex)
-		}
-		if evidenceIndex > 0 && !lessEvidenceRef(value.EvidenceRefs[evidenceIndex-1], evidence) {
-			return Context{}, fmt.Errorf("%s.evidence_refs must be unique and in deterministic order", prefix)
+		if _, exists := seenUnitIDs[unit.ID]; exists {
+			return nil, fmt.Errorf("units contains duplicate unit id %d", unit.ID)
 		}
+		seenUnitIDs[unit.ID] = struct{}{}
 	}
 	return value, nil
 }

-func validateRefIdentity(sourceID string, ref source.SourceRef, field string) error {
-	if ref.SourceID != sourceID {
-		return fmt.Errorf("%s.source_id does not match source_id", field)
+func validateUnitRef(unit source.SourceUnit, unitIndex int) error {
+	prefix := fmt.Sprintf("units[%d].ref", unitIndex)
+	if strings.TrimSpace(unit.Ref.SourceID) == "" || strings.TrimSpace(unit.Ref.SourceID) != unit.Ref.SourceID {
+		return fmt.Errorf("%s.source_id must be a non-empty trimmed string", prefix)
 	}
-	if ref.StartUnitID <= 0 || ref.EndUnitID <= 0 {
-		return fmt.Errorf("%s endpoints must be positive", field)
-	}
-	return nil
-}
-
-func requireIdentity(field, value string) error {
-	if strings.TrimSpace(value) == "" || strings.TrimSpace(value) != value {
-		return fmt.Errorf("%s must be a non-empty trimmed string", field)
+	if unit.Ref.StartUnitID != unit.ID || unit.Ref.EndUnitID != unit.ID {
+		return fmt.Errorf("%s must identify unit id %d", prefix, unit.ID)
 	}
 	return nil
 }

 func clone(value Document) (Document, error) {
-	value.SelectedLanes = append([]string(nil), value.SelectedLanes...)
-	if value.Contexts == nil {
-		value.Contexts = make([]Context, 0)
-	} else {
-		contexts := make([]Context, len(value.Contexts))
-		for contextIndex, context := range value.Contexts {
-			contexts[contextIndex].ContextRef = context.ContextRef
-			contexts[contextIndex].EvidenceRefs = append([]EvidenceRef(nil), context.EvidenceRefs...)
-			contexts[contextIndex].Units = make([]source.SourceUnit, len(context.Units))
-			for unitIndex, unit := range context.Units {
-				cloned, err := cloneSourceUnit(unit)
-				if err != nil {
-					return Document{}, fmt.Errorf("clone contexts[%d].units[%d]: %w", contextIndex, unitIndex, err)
-				}
-				contexts[contextIndex].Units[unitIndex] = cloned
-			}
-		}
-		value.Contexts = contexts
+	if value == nil {
+		return nil, nil
 	}
-	return value, nil
+	cloned := make(Document, len(value))
+	for unitIndex, unit := range value {
+		owned, err := cloneSourceUnit(unit)
+		if err != nil {
+			return nil, fmt.Errorf("clone units[%d]: %w", unitIndex, err)
+		}
+		cloned[unitIndex] = owned
+	}
+	return cloned, nil
 }

 func cloneSourceUnit(unit source.SourceUnit) (source.SourceUnit, error) {
--- a/internal/framework/evidencecontext/evidencecontext_test.go
+++ b/internal/framework/evidencecontext/evidencecontext_test.go
@@ -2,7 +2,6 @@ package evidencecontext

 import (
 	"bytes"
-	"encoding/json"
 	"math"
 	"os"
 	"reflect"
@@ -12,126 +11,56 @@ import (
 	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
 )

-func TestBuildExpandsAndMergesEvidenceByDocumentPosition(t *testing.T) {
+func TestBuildSelectsExpandedSourceUnitUnion(t *testing.T) {
 	for _, test := range []struct {
-		name      string
-		window    int
-		evidence  []LaneEvidence
-		wantUnits [][]int
-		wantRefs  [][]EvidenceRef
+		name    string
+		window  int
+		refs    []source.SourceRef
+		wantIDs []int
 	}{
-		{
-			name:      "zero window",
-			evidence:  []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(3, 3)}}},
-			wantUnits: [][]int{{3}},
-			wantRefs:  [][]EvidenceRef{{{LaneID: "npcs", SourceRef: ref(3, 3)}}},
-		},
-		{
-			name:      "non monotonic ids use positions and clip boundaries",
-			window:    1,
-			evidence:  []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(3, 3)}}},
-			wantUnits: [][]int{{10, 3, 30}},
-			wantRefs:  [][]EvidenceRef{{{LaneID: "npcs", SourceRef: ref(3, 3)}}},
-		},
-		{
-			name:      "separate gaps stay separate",
-			evidence:  []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(10, 10), ref(50, 50)}}},
-			wantUnits: [][]int{{10}, {50}},
-			wantRefs:  [][]EvidenceRef{{{LaneID: "npcs", SourceRef: ref(10, 10)}}, {{LaneID: "npcs", SourceRef: ref(50, 50)}}},
-		},
-		{
-			name:      "overlapping windows merge",
-			window:    1,
-			evidence:  []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(3, 3), ref(30, 30)}}},
-			wantUnits: [][]int{{10, 3, 30, 7}},
-			wantRefs:  [][]EvidenceRef{{{LaneID: "npcs", SourceRef: ref(3, 3)}, {LaneID: "npcs", SourceRef: ref(30, 30)}}},
-		},
-		{
-			name:      "contiguous windows merge",
-			window:    1,
-			evidence:  []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(10, 10), ref(7, 7)}}},
-			wantUnits: [][]int{{10, 3, 30, 7, 50}},
-			wantRefs:  [][]EvidenceRef{{{LaneID: "npcs", SourceRef: ref(7, 7)}, {LaneID: "npcs", SourceRef: ref(10, 10)}}},
-		},
-		{
-			name: "duplicate contributions retain unique lane attribution",
-			evidence: []LaneEvidence{
-				{LaneID: "spells", SourceRefs: []source.SourceRef{ref(30, 30), ref(30, 30)}},
-				{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(30, 30)}},
-			},
-			wantUnits: [][]int{{30}},
-			wantRefs:  [][]EvidenceRef{{{LaneID: "npcs", SourceRef: ref(30, 30)}, {LaneID: "spells", SourceRef: ref(30, 30)}}},
-		},
-		{
-			name:      "empty contributions retain explicit empty contexts",
-			evidence:  []LaneEvidence{{LaneID: "npcs"}},
-			wantUnits: [][]int{},
-			wantRefs:  [][]EvidenceRef{},
-		},
-		{
-			name:      "largest window clips without overflow",
-			window:    math.MaxInt,
-			evidence:  []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(30, 30)}}},
-			wantUnits: [][]int{{10, 3, 30, 7, 50}},
-			wantRefs:  [][]EvidenceRef{{{LaneID: "npcs", SourceRef: ref(30, 30)}}},
-		},
+		{name: "zero window", refs: []source.SourceRef{ref(3, 3)}, wantIDs: []int{3}},
+		{name: "non monotonic IDs use document positions", window: 1, refs: []source.SourceRef{ref(3, 3)}, wantIDs: []int{10, 3, 30}},
+		{name: "boundary clamping", window: 1, refs: []source.SourceRef{ref(10, 10), ref(50, 50)}, wantIDs: []int{10, 3, 7, 50}},
+		{name: "overlapping and adjacent windows merge", window: 1, refs: []source.SourceRef{ref(3, 3), ref(30, 30), ref(30, 30)}, wantIDs: []int{10, 3, 30, 7}},
+		{name: "adjacent expanded ranges merge", window: 1, refs: []source.SourceRef{ref(10, 10), ref(7, 7)}, wantIDs: []int{10, 3, 30, 7, 50}},
+		{name: "largest window clips without overflow", window: math.MaxInt, refs: []source.SourceRef{ref(30, 30)}, wantIDs: []int{10, 3, 30, 7, 50}},
+		{name: "no references returns an initialized empty document", wantIDs: []int{}},
 	} {
 		t.Run(test.name, func(t *testing.T) {
-			document := testDocument(t)
-			got, err := Build(BuildRequest{Source: document, WindowUnits: test.window, SelectedLanes: []string{"spells", "npcs"}, LaneEvidence: test.evidence})
+			got, err := Build(BuildRequest{Source: testDocument(t), WindowUnits: test.window, SourceRefs: test.refs})
 			if err != nil {
 				t.Fatalf("Build() error = %v", err)
 			}
-			if want := []string{"npcs", "spells"}; !reflect.DeepEqual(got.SelectedLanes, want) {
-				t.Fatalf("SelectedLanes = %#v, want %#v", got.SelectedLanes, want)
+			if got == nil {
+				t.Fatal("Build() returned a nil document")
 			}
-			if got.WindowUnits != test.window || got.SourceID != document.ID || got.SourceDigest != document.Digest {
-				t.Fatalf("Build() identity = %#v, want source and window identity", got)
-			}
-			if actual := contextUnitIDs(got.Contexts); !reflect.DeepEqual(actual, test.wantUnits) {
-				t.Fatalf("context unit ids = %#v, want %#v", actual, test.wantUnits)
-			}
-			if actual := contextEvidenceRefs(got.Contexts); !reflect.DeepEqual(actual, test.wantRefs) {
-				t.Fatalf("context evidence refs = %#v, want %#v", actual, test.wantRefs)
+			if actual := unitIDs(got); !reflect.DeepEqual(actual, test.wantIDs) {
+				t.Fatalf("unit IDs = %#v, want %#v", actual, test.wantIDs)
 			}
 		})
 	}
 }

-func TestBuildIsStableAndOwnsSourceAndInputs(t *testing.T) {
+func TestBuildCopiesSelectedUnitsAndMetadata(t *testing.T) {
 	document := testDocument(t)
-	refs := []source.SourceRef{ref(30, 30), ref(3, 3)}
-	request := BuildRequest{
-		Source:        document,
-		WindowUnits:   1,
-		SelectedLanes: []string{"spells", "npcs"},
-		LaneEvidence:  []LaneEvidence{{LaneID: "spells", SourceRefs: refs}, {LaneID: "npcs", SourceRefs: []source.SourceRef{ref(3, 3)}}},
-	}
-	first, err := Build(request)
+	first, err := Build(BuildRequest{Source: document, WindowUnits: 1, SourceRefs: []source.SourceRef{ref(3, 3)}})
 	if err != nil {
 		t.Fatal(err)
 	}
-	secondRequest := request
-	secondRequest.LaneEvidence = []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(3, 3)}}, {LaneID: "spells", SourceRefs: []source.SourceRef{ref(3, 3), ref(30, 30)}}}
-	second, err := Build(secondRequest)
+	second, err := Build(BuildRequest{Source: document, WindowUnits: 1, SourceRefs: []source.SourceRef{ref(3, 3)}})
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !reflect.DeepEqual(first, second) {
-		t.Fatalf("Build() order differs:\nfirst: %#v\nsecond: %#v", first, second)
+	if !reflect.DeepEqual(first[0], document.Units[0]) {
+		t.Fatalf("first unit = %#v, want unchanged source unit %#v", first[0], document.Units[0])
 	}
-	first.SelectedLanes[0] = "changed"
-	first.Contexts[0].Units[0].Metadata["nested"].(map[string]any)["value"] = "changed"
+	first[0].Metadata["nested"].(map[string]any)["value"] = "changed"
 	if document.Units[0].Metadata["nested"].(map[string]any)["value"] != "original" {
-		t.Fatal("Build() returned metadata aliases to source document")
+		t.Fatal("Build() returned metadata aliases to the source document")
 	}
 	document.Units[0].Metadata["nested"].(map[string]any)["value"] = "later"
-	if second.Contexts[0].Units[0].Metadata["nested"].(map[string]any)["value"] != "original" {
-		t.Fatal("Build() retained metadata aliases to source document")
-	}
-	refs[0].StartUnitID = 999
-	if !containsEvidenceRef(second.Contexts[0].EvidenceRefs, ref(30, 30)) {
-		t.Fatal("Build() retained source-reference input aliases")
+	if second[0].Metadata["nested"].(map[string]any)["value"] != "original" {
+		t.Fatal("Build() retained metadata aliases to the source document")
 	}
 }

@@ -142,18 +71,11 @@ func TestBuildRejectsInvalidInputs(t *testing.T) {
 		want   string
 	}{
 		{name: "negative window", mutate: func(request *BuildRequest) { request.WindowUnits = -1 }, want: "window_units"},
-		{name: "blank selected lane", mutate: func(request *BuildRequest) { request.SelectedLanes = []string{" "} }, want: "selected_lanes"},
-		{name: "duplicate selected lane", mutate: func(request *BuildRequest) { request.SelectedLanes = []string{"npcs", " npcs "} }, want: "duplicated"},
-		{name: "unselected contribution", mutate: func(request *BuildRequest) {
-			request.LaneEvidence = []LaneEvidence{{LaneID: "other", SourceRefs: []source.SourceRef{ref(3, 3)}}}
-		}, want: "not selected"},
 		{name: "source digest mismatch", mutate: func(request *BuildRequest) { request.Source.Digest = "sha256:" + strings.Repeat("0", 64) }, want: "does not match"},
-		{name: "invalid reference", mutate: func(request *BuildRequest) {
-			request.LaneEvidence = []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(99, 99)}}}
-		}, want: "source reference[0]"},
+		{name: "invalid reference", mutate: func(request *BuildRequest) { request.SourceRefs = []source.SourceRef{ref(99, 99)} }, want: "source reference[0]"},
 	} {
 		t.Run(test.name, func(t *testing.T) {
-			request := BuildRequest{Source: testDocument(t), SelectedLanes: []string{"npcs"}, LaneEvidence: []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(3, 3)}}}}
+			request := BuildRequest{Source: testDocument(t), SourceRefs: []source.SourceRef{ref(3, 3)}}
 			test.mutate(&request)
 			if _, err := Build(request); err == nil || !strings.Contains(err.Error(), test.want) {
 				t.Fatalf("Build() error = %v, want %q", err, test.want)
@@ -162,7 +84,7 @@ func TestBuildRejectsInvalidInputs(t *testing.T) {
 	}
 }

-func TestCodecRoundTripsCompactFixtureAndOwnsDecodedValues(t *testing.T) {
+func TestCodecRoundTripsFixtureAndOwnsValues(t *testing.T) {
 	fixture, err := os.ReadFile("testdata/source_evidence_context.v1.json")
 	if err != nil {
 		t.Fatal(err)
@@ -179,15 +101,16 @@ func TestCodecRoundTripsCompactFixtureAndOwnsDecodedValues(t *testing.T) {
 	if !bytes.Equal(encoded, bytes.TrimSpace(fixture)) {
 		t.Fatalf("fixture does not use canonical encoding\nwant: %s\n got: %s", fixture, encoded)
 	}
-	value.Contexts[0].Units[0].Text = "changed"
+	value[0].Text = "changed"
 	decoded, err := codec.Decode(encoded)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if decoded.Contexts[0].Units[0].Text != "The party meets Rowan." {
+	if decoded[0].Text != "The party meets Rowan." {
 		t.Fatal("Encode() retained mutable document storage")
 	}
-	built, err := Build(BuildRequest{Source: testDocument(t), WindowUnits: 1, SelectedLanes: []string{"npcs"}, LaneEvidence: []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(3, 3)}}}})
+
+	built, err := Build(BuildRequest{Source: testDocument(t), WindowUnits: 1, SourceRefs: []source.SourceRef{ref(3, 3)}})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -203,82 +126,51 @@ func TestCodecRoundTripsCompactFixtureAndOwnsDecodedValues(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	first.Contexts[0].Units[0].Metadata["nested"].(map[string]any)["value"] = "changed"
-	if second.Contexts[0].Units[0].Metadata["nested"].(map[string]any)["value"] != "original" {
+	first[0].Metadata["nested"].(map[string]any)["value"] = "changed"
+	if second[0].Metadata["nested"].(map[string]any)["value"] != "original" {
 		t.Fatal("Decode() returned metadata aliases")
 	}
 }

-func TestCodecRejectsInvalidDurableBoundaries(t *testing.T) {
-	value, err := Build(BuildRequest{Source: testDocument(t), SelectedLanes: []string{"npcs"}, LaneEvidence: []LaneEvidence{{LaneID: "npcs", SourceRefs: []source.SourceRef{ref(3, 3)}}}})
-	if err != nil {
-		t.Fatal(err)
-	}
+func TestCodecRejectsInvalidDurablePayloads(t *testing.T) {
 	for _, test := range []struct {
-		name   string
-		mutate func(*Document)
+		name    string
+		content string
 	}{
-		{name: "unsorted lanes", mutate: func(value *Document) { value.SelectedLanes = []string{"z", "a"} }},
-		{name: "context range mismatch", mutate: func(value *Document) { value.Contexts[0].ContextRef.EndUnitID = 999 }},
-		{name: "mismatched evidence source", mutate: func(value *Document) { value.Contexts[0].EvidenceRefs[0].SourceRef.SourceID = "other" }},
-		{name: "invalid evidence range", mutate: func(value *Document) {
-			value.Contexts[0].EvidenceRefs[0].SourceRef.StartUnitID = 10
-		}},
-		{name: "duplicate context unit", mutate: func(value *Document) { value.Contexts = append(value.Contexts, value.Contexts[0]) }},
+		{name: "null", content: "null"},
+		{name: "wrapper object", content: `{"units":[]}`},
+		{name: "missing required unit field", content: `[{"id":1,"kind":"segment","ref":{"source_id":"session","start_unit_id":1,"end_unit_id":1}}]`},
+		{name: "unknown unit field", content: `[{"id":1,"kind":"segment","text":"text","ref":{"source_id":"session","start_unit_id":1,"end_unit_id":1},"unknown":true}]`},
+		{name: "unknown reference field", content: `[{"id":1,"kind":"segment","text":"text","ref":{"source_id":"session","start_unit_id":1,"end_unit_id":1,"unknown":true}}]`},
+		{name: "invalid self reference", content: `[{"id":1,"kind":"segment","text":"text","ref":{"source_id":"session","start_unit_id":1,"end_unit_id":2}}]`},
+		{name: "duplicate units", content: `[{"id":1,"kind":"segment","text":"one","ref":{"source_id":"session","start_unit_id":1,"end_unit_id":1}},{"id":1,"kind":"segment","text":"two","ref":{"source_id":"session","start_unit_id":1,"end_unit_id":1}}]`},
+		{name: "multiple JSON values", content: `[] []`},
 	} {
 		t.Run(test.name, func(t *testing.T) {
-			candidate, err := clone(value)
-			if err != nil {
-				t.Fatal(err)
-			}
-			test.mutate(&candidate)
-			if _, err := New().Encode(candidate); err == nil {
-				t.Fatal("Encode() error = nil, want durable model rejection")
-			}
-		})
-	}
-	content, err := New().Encode(value)
-	if err != nil {
-		t.Fatal(err)
-	}
-	for _, test := range []struct {
-		name   string
-		mutate func(map[string]any)
-	}{
-		{name: "missing contexts", mutate: func(value map[string]any) { delete(value, "contexts") }},
-		{name: "null contexts", mutate: func(value map[string]any) { value["contexts"] = nil }},
-		{name: "unknown fixed field", mutate: func(value map[string]any) { value["unknown"] = true }},
-		{name: "missing units", mutate: func(value map[string]any) { delete(contextObject(value, 0), "units") }},
-		{name: "null evidence refs", mutate: func(value map[string]any) { contextObject(value, 0)["evidence_refs"] = nil }},
-	} {
-		t.Run(test.name, func(t *testing.T) {
-			raw := decodeJSON(t, content)
-			test.mutate(raw)
-			mutated, err := json.Marshal(raw)
-			if err != nil {
-				t.Fatal(err)
-			}
-			if _, err := New().Decode(mutated); err == nil {
+			if _, err := New().Decode([]byte(test.content)); err == nil {
 				t.Fatal("Decode() error = nil, want strict payload rejection")
 			}
 		})
 	}
-	if _, err := New().Decode(append(content, []byte(" {}")...)); err == nil {
-		t.Fatal("Decode() error = nil, want trailing JSON rejection")
+	if _, err := New().Encode(nil); err == nil {
+		t.Fatal("Encode(nil) error = nil, want array rejection")
 	}
 }

-func TestSerializeUsesFixedArtifactIdentity(t *testing.T) {
-	artifact, err := Serialize(BuildRequest{Source: testDocument(t), SelectedLanes: []string{"npcs"}})
+func TestSerializeUsesFixedArtifactIdentityAndEmptyArray(t *testing.T) {
+	artifact, err := Serialize(BuildRequest{Source: testDocument(t)})
 	if err != nil {
 		t.Fatal(err)
 	}
 	if artifact.Kind != ArtifactKind || artifact.MediaType != MediaType || artifact.Schema.ID != SchemaID || artifact.Schema.Name != SchemaName || artifact.Schema.Version != SchemaVersion {
 		t.Fatalf("Serialize() = %#v, want fixed artifact identity", artifact)
 	}
+	if string(artifact.Content) != "[]" {
+		t.Fatalf("Serialize() content = %s, want []", artifact.Content)
+	}
 	decoded, err := New().Decode(artifact.Content)
-	if err != nil || len(decoded.Contexts) != 0 || decoded.Contexts == nil {
-		t.Fatalf("Decode(Serialize()) = %#v, %v; want explicit empty contexts", decoded, err)
+	if err != nil || decoded == nil || len(decoded) != 0 {
+		t.Fatalf("Decode(Serialize()) = %#v, %v; want explicit empty array", decoded, err)
 	}
 }

@@ -306,45 +198,10 @@ func ref(start, end int) source.SourceRef {
 	return source.SourceRef{SourceID: "session", StartUnitID: start, EndUnitID: end}
 }

-func contextUnitIDs(contexts []Context) [][]int {
-	values := make([][]int, len(contexts))
-	for index, context := range contexts {
-		values[index] = make([]int, len(context.Units))
-		for unitIndex, unit := range context.Units {
-			values[index][unitIndex] = unit.ID
-		}
+func unitIDs(units Document) []int {
+	values := make([]int, len(units))
+	for index, unit := range units {
+		values[index] = unit.ID
 	}
 	return values
 }
-
-func contextEvidenceRefs(contexts []Context) [][]EvidenceRef {
-	values := make([][]EvidenceRef, len(contexts))
-	for index, context := range contexts {
-		values[index] = append([]EvidenceRef(nil), context.EvidenceRefs...)
-	}
-	return values
-}
-
-func containsEvidenceRef(values []EvidenceRef, want source.SourceRef) bool {
-	for _, value := range values {
-		if value.SourceRef == want {
-			return true
-		}
-	}
-	return false
-}
-
-func decodeJSON(t *testing.T, content []byte) map[string]any {
-	t.Helper()
-	decoder := json.NewDecoder(bytes.NewReader(content))
-	decoder.UseNumber()
-	var value map[string]any
-	if err := decoder.Decode(&value); err != nil {
-		t.Fatal(err)
-	}
-	return value
-}
-
-func contextObject(value map[string]any, index int) map[string]any {
-	return value["contexts"].([]any)[index].(map[string]any)
-}
--- a/internal/framework/evidencecontext/model.go
+++ b/internal/framework/evidencecontext/model.go
@@ -14,37 +14,12 @@ const (
 	MediaType                            = "application/json"
 )

-// Document is the durable union of direct evidence and surrounding source
-// context selected for one accepted source document.
-type Document struct {
-	SourceID      string    `json:"source_id"`
-	SourceDigest  string    `json:"source_digest"`
-	WindowUnits   int       `json:"window_units"`
-	SelectedLanes []string  `json:"selected_lanes"`
-	Contexts      []Context `json:"contexts"`
-}
+// Document is the durable selected source-unit excerpt.
+type Document []source.SourceUnit

-type Context struct {
-	ContextRef   source.SourceRef    `json:"context_ref"`
-	EvidenceRefs []EvidenceRef       `json:"evidence_refs"`
-	Units        []source.SourceUnit `json:"units"`
-}
-
-type EvidenceRef struct {
-	LaneID    string           `json:"lane_id"`
-	SourceRef source.SourceRef `json:"source_ref"`
-}
-
-// LaneEvidence attributes direct source references to one selected lane.
-type LaneEvidence struct {
-	LaneID     string             `json:"lane_id"`
-	SourceRefs []source.SourceRef `json:"source_refs"`
-}
-
-// BuildRequest supplies accepted source material and direct lane evidence.
+// BuildRequest supplies accepted source material and projected source references.
 type BuildRequest struct {
-	Source        *source.SourceDocument
-	WindowUnits   int
-	SelectedLanes []string
-	LaneEvidence  []LaneEvidence
+	Source      *source.SourceDocument
+	WindowUnits int
+	SourceRefs  []source.SourceRef
 }
--- a/internal/framework/evidencecontext/testdata/source_evidence_context.v1.json
+++ b/internal/framework/evidencecontext/testdata/source_evidence_context.v1.json
@@ -1 +1 @@
-{"source_id":"session-alpha","source_digest":"sha256:0000000000000000000000000000000000000000000000000000000000000000","window_units":0,"selected_lanes":["npcs"],"contexts":[{"context_ref":{"source_id":"session-alpha","start_unit_id":13,"end_unit_id":13},"evidence_refs":[{"lane_id":"npcs","source_ref":{"source_id":"session-alpha","start_unit_id":13,"end_unit_id":13}}],"units":[{"id":13,"kind":"transcript_segment","text":"The party meets Rowan.","ref":{"source_id":"session-alpha","start_unit_id":13,"end_unit_id":13}}]}]}
+[{"id":13,"kind":"transcript_segment","text":"The party meets Rowan.","ref":{"source_id":"session-alpha","start_unit_id":13,"end_unit_id":13}}]
--- a/internal/framework/pipeline/evidence_output.go
+++ b/internal/framework/pipeline/evidence_output.go
@@ -20,7 +20,6 @@ type debugEvidenceContextSummary struct {
 	SchemaVersion string                 `json:"schema_version"`
 	SelectedLanes []string               `json:"selected_lanes"`
 	WindowUnits   int                    `json:"window_units"`
-	ContextCount  int                    `json:"context_count"`
 	UnitCount     int                    `json:"unit_count"`
 	SourceDigest  string                 `json:"source_digest"`
 }
@@ -49,10 +48,9 @@ func buildOutputEvidenceContext(prepared *PreparedPipeline, doc *source.SourceDo
 	}

 	request := evidencecontext.BuildRequest{
-		Source:        doc,
-		WindowUnits:   prepared.evidencePlan.policy.WindowUnits,
-		SelectedLanes: append([]string(nil), prepared.evidencePlan.policy.LaneIDs...),
-		LaneEvidence:  make([]evidencecontext.LaneEvidence, 0, len(prepared.evidencePlan.lanes)),
+		Source:      doc,
+		WindowUnits: prepared.evidencePlan.policy.WindowUnits,
+		SourceRefs:  make([]source.SourceRef, 0),
 	}
 	for _, lane := range prepared.evidencePlan.lanes {
 		output, ok := byLane[lane.laneID]
@@ -73,10 +71,7 @@ func buildOutputEvidenceContext(prepared *PreparedPipeline, doc *source.SourceDo
 		if err != nil {
 			return nil, nil, fmt.Errorf("evidence context output lane %q: accepted normalized artifact cannot be projected", lane.laneID)
 		}
-		request.LaneEvidence = append(request.LaneEvidence, evidencecontext.LaneEvidence{
-			LaneID:     lane.laneID,
-			SourceRefs: append([]source.SourceRef(nil), references...),
-		})
+		request.SourceRefs = append(request.SourceRefs, references...)
 	}

 	document, err := evidencecontext.Build(request)
@@ -99,13 +94,10 @@ func buildOutputEvidenceContext(prepared *PreparedPipeline, doc *source.SourceDo
 		SchemaID:      artifact.Schema.ID,
 		SchemaName:    artifact.Schema.Name,
 		SchemaVersion: artifact.Schema.Version,
-		SelectedLanes: append([]string(nil), document.SelectedLanes...),
-		WindowUnits:   document.WindowUnits,
-		ContextCount:  len(document.Contexts),
-		SourceDigest:  document.SourceDigest,
-	}
-	for _, context := range document.Contexts {
-		summary.UnitCount += len(context.Units)
+		SelectedLanes: append([]string(nil), prepared.evidencePlan.policy.LaneIDs...),
+		WindowUnits:   prepared.evidencePlan.policy.WindowUnits,
+		SourceDigest:  doc.Digest,
+		UnitCount:     len(document),
 	}
 	return contracts.CloneSerializedArtifactPointer(artifact), &summary, nil
 }
--- a/internal/framework/pipeline/evidence_output_test.go
+++ b/internal/framework/pipeline/evidence_output_test.go
@@ -97,14 +97,11 @@ func TestRunnerBuildsEvidenceContextFromSelectedNormalizedOutputs(t *testing.T)
 	}

 	value := decodeCapturedEvidence(t, encoder)
-	if !reflect.DeepEqual(value.SelectedLanes, []string{"alpha", "beta", "inactive"}) || len(value.Contexts) != 1 || len(value.Contexts[0].Units) != 3 {
+	if actual := []int{value[0].ID, value[1].ID, value[2].ID}; !reflect.DeepEqual(actual, []int{1, 2, 3}) {
 		t.Fatalf("evidence context = %#v, want selected union", value)
 	}
-	if got := value.Contexts[0].EvidenceRefs; len(got) != 2 || got[0].LaneID != "alpha" || got[1].LaneID != "beta" {
-		t.Fatalf("evidence refs = %#v, want both selected lanes", got)
-	}
 	debugJSON := string(debug.json["output/evidence-context.json"])
-	if strings.Contains(debugJSON, "text-1") || strings.Contains(debugJSON, "metadata") || !strings.Contains(debugJSON, `"artifact_kind":"source/evidence-context"`) || !strings.Contains(debugJSON, `"schema_id":"notarius.source.evidence_context"`) || !strings.Contains(debugJSON, `"context_count":1`) || !strings.Contains(debugJSON, `"unit_count":3`) {
+	if strings.Contains(debugJSON, "text-1") || strings.Contains(debugJSON, "metadata") || !strings.Contains(debugJSON, `"artifact_kind":"source/evidence-context"`) || !strings.Contains(debugJSON, `"schema_id":"notarius.source.evidence_context"`) || strings.Contains(debugJSON, "context_count") || !strings.Contains(debugJSON, `"unit_count":3`) {
 		t.Fatalf("evidence debug envelope = %s, want only allowlisted summary", debugJSON)
 	}
 }
@@ -134,7 +131,7 @@ func TestRunnerEvidenceContextOmitsAbsentAndRejectedLanes(t *testing.T) {
 		t.Fatalf("rejections = %#v, want rejected lane unchanged", result.Rejected)
 	}
 	value := decodeCapturedEvidence(t, encoder)
-	if len(value.Contexts) != 1 || len(value.Contexts[0].EvidenceRefs) != 1 || value.Contexts[0].EvidenceRefs[0].LaneID != "present" {
+	if len(value) != 1 || value[0].ID != 1 {
 		t.Fatalf("evidence context = %#v, want present lane only", value)
 	}
 }
@@ -232,7 +229,7 @@ func TestRunnerEvidenceContextRebuildsFromAcceptedCheckpoint(t *testing.T) {
 		t.Fatalf("Run() error = %v", err)
 	}
 	value := decodeCapturedEvidence(t, encoder)
-	if len(value.Contexts) != 1 || value.Contexts[0].EvidenceRefs[0].LaneID != "notes" {
+	if len(value) != 1 || value[0].ID != 1 {
 		t.Fatalf("evidence context = %#v, want checkpointed normalized output", value)
 	}
 }