# Internal: Artifacts

## Purpose

Explain the artifact registry, runtime catalog, resolver, previous-input
requirements, and shared remote current-state mechanics implemented by
`internal/artifacts`. Configuration fields that accept source IDs belong in
[Configuration](../config.md); physical placement belongs in
[Operations](../operations.md).

## Built-in Source IDs

The internal registry recognizes these stable built-in source IDs:

- `narratio.transcript.base`
- `narratio.transcript.polished`
- `narratio.transcript.final`
- `narratio.transcript.final_trimmed`
- `narratio.transcript.final_markdown`
- `narratio.transcript.final_trimmed_markdown`
- `narratio.bounds.session`

Registry entries bind each ID to its producer, output kind, canonical fallback,
and content validator. The focused stage documents own their input/output flow;
[Configuration](../config.md) owns where operators may select these IDs.

## Configured, Extraction, And Previous-Session Sources

- configured source ID format: `narratio.artifact.<artifact_key>`
- extraction source ID format: `narratio.extraction.<output_key>`
- previous-session source ID format: `narratio.previous_session.artifact.<artifact_key>`

All formats are validated by strict source-policy rules. Configured artifact and
extraction keys use `^[a-z][a-z0-9_]*$`; source parsers never normalize an
unrecognized token into a valid source. Extraction sources are registered only
from `pipeline.notarius.outputs`; the Notarius index has no selectable source
ID.

## Runtime Catalog

`ArtifactCatalog` tracks:

- `planned`: source registered for run context;
- `executable`: included in the effective analyze artifact set;
- `available`: local file exists and validates;
- `provenance`: availability source.

Configured definitions are always registered. Without an explicit selection,
the effective analyze set contains enabled definitions. With `--artifacts`, the
exact named configured definitions become the effective set for that invocation,
regardless of their `enabled` value; dependencies are not added implicitly.
Availability is separate from executability: a non-executable configured output
may be reused from a canonical non-empty file, while an executable definition
is generated by analyze. Extraction entries are registered from configuration
and become available only after compatible extraction evidence is hydrated.

Current provenance values:

- `generated.current_analyze_run`
- `filesystem.disabled_artifact_output`
- `manifest.inputs.previous_cache`
- `current_session.previous_cache`

## Resolution Rules

Built-ins:

1. manifest producer outputs (when present)
2. canonical session-path fallback

Configured sources (`narratio.artifact.*`):

- resolve only through runtime catalog availability.

Extraction sources (`narratio.extraction.*`):

- use the shared typed bundle evidence inspection in `extraction_evidence.go`;
- require a current successful extract record with the exact configured source,
  compatible contract and Notarius provenance, a confined regular durable
  payload, matching checksum, and the current resolved trimmed-transcript
  identity;
- remain unavailable unless catalog hydration receives valid evidence. Resume
  treats absent or obsolete evidence as a rerun decision and unsafe evidence as
  an error; and
- are never inferred by scanning the Notarius bundle directory.

Previous-session sources (`narratio.previous_session.artifact.*`):

- resolve only from local `previous/` cache state;
- prefer manifest-backed previous-input paths;
- fallback to existing previous-cache filesystem paths.

Source absence is evaluated by the consuming artifact input. An optional input
is omitted from that invocation; a required input fails resolution. This is
separate from a stage's lifecycle outcome.

Validation by content type:

- transcript JSON built-ins: JSON with top-level `segments` array;
- transcript Markdown built-ins: non-empty text file;
- bounds built-in: valid JSON;
- configured/previous-session artifact files: non-empty text file.

## Previous Requirement Collection

`CollectPreviousArtifactRequirements`:

- scans the effective configured artifact set;
- extracts only canonical previous-session sources;
- deduplicates by artifact key;
- merges required and optional references (required wins);
- returns deterministic ordering and source locations.

## Current-State Helpers

Artifacts package owns shared remote current-state loading mechanics used by
restore, status and validation checks, and previous-cache planning.

For a new-protocol current state, the pointer-selected immutable commit is the
complete restore authority. Callers receive its declared object identities and
must not supplement them by listing mutable session prefixes. The legacy reader
is intentionally separate and remains migration-only support.

The reader opens each small control object directly and enforces owner-specific
limits before decoding: 64 KiB for the mutable commit pointer, 4 MiB for the
immutable commit manifest, and 8 MiB for the selected session manifest. Legacy
compatibility applies a 4 KiB limit to `current/run_id.txt` and the same 8 MiB
manifest limit to `current/manifest.json`. These are exposed as
`MaxCurrentCommitPointerBytes`, `MaxRemoteCommitManifestBytes`,
`MaxRemoteSessionManifestBytes`, `MaxLegacyCurrentRunPointerBytes`, and
`MaxLegacyCurrentManifestBytes`.

Each read uses the generation and size metadata returned with its opened body.
Actual bytes remain subject to a limit-plus-one read even if size metadata is
absent or inaccurate. Immutable selections then retain their declared-size,
checksum, generation, and identity checks. No current-state control object is
downloaded through a temporary file.

Core helpers:

- `LoadCurrentState`
- `ValidateCurrentStateIdentity`
- `RemoteCommitManifest` and `CurrentCommitPointer`

Typed missing-state errors:

- `CurrentRunPointerMissingError` (`ErrCurrentRunPointerMissing`)
- `CurrentManifestMissingError` (`ErrCurrentManifestMissing`)

Identity validation supports caller-provided expectations:

- expected campaign;
- expected session ID;
- expected run ID, or pointer/manifest run-ID consistency check.

Caller policy is intentionally outside artifacts helpers:

- some callers fail on missing current state;
- some callers downgrade missing state to status/findings;
- some callers skip optional behavior when state is missing.

## Key Path Helpers

`internal/artifacts/paths.go` and S3-key helpers define canonical helpers for:

- session/work/run paths;
- previous-cache paths;
- spool/cache paths;
- S3 session/run/current-state key layout.

New publication creates run-scoped immutable objects, including
`runs/{run_id}/commit.json` and `runs/{run_id}/session-manifest.json`. The sole
mutable selector is `current/commit-pointer.json`; readers verify its selected
commit and declared object generations/checksums. Legacy current-pair loading
is confined to `current_state_legacy.go` for migration only.

Campaign, session, and Narratio run IDs are validated as portable opaque
segments at configuration and artifact boundaries before they can be used in a
workspace or S3 namespace. Previous-artifact destinations remain typed,
multi-segment relative paths and are confined beneath `previous/artifacts`; they
are not treated as opaque identifiers.

See [Workspace Internals](workspace.md) for how callers consume local helpers
and [Operations](../operations.md#local-state-layout) for the authoritative
physical layout.

## Invariants

- source ID formats are stable contracts;
- artifact resolution is deterministic and manifest-aware;
- extraction sources are available only from a compatible successful manifest
  record;
- previous-session source resolution in `analyze` is local-only;
- remote current-state key construction remains centralized in artifacts helpers.

## Implementation And Tests

- Registry and resolution: `internal/artifacts/artifact_resolver.go`,
  `internal/artifacts/catalog.go`, `internal/artifacts/transcripts.go`,
  `internal/artifacts/extraction_catalog.go`,
  `internal/artifacts/extraction_evidence.go`,
  `internal/artifacts/extraction_input.go`
- Current state: `internal/artifacts/current_state.go`,
  `internal/artifacts/current_state_commit.go`,
  `internal/artifacts/current_state_legacy.go`
- Paths and keys: `internal/artifacts/paths.go`,
  `internal/artifacts/s3_keys.go`
- Previous requirements: `internal/artifacts/previous_requirements.go`
- Tests: `internal/artifacts/artifact_resolver_test.go`,
  `internal/artifacts/catalog_test.go`,
  `internal/artifacts/extraction_catalog_test.go`,
  `internal/artifacts/current_state_test.go`,
  `internal/artifacts/paths_model_test.go`,
  `internal/artifacts/previous_requirements_test.go`