# Internal: Artifacts

## Purpose
Define Narratio artifact identity, catalog, and source-resolution behavior for:
- built-in session artifacts;
- configured analyze artifacts;
- canonical previous-session artifact sources.

## Inputs and outputs
Inputs:
- configured input sources (`pipeline.scriptorium.artifacts.*.inputs.*.source`);
- session paths and manifest inputs/outputs;
- runtime catalog state.

Outputs:
- resolved artifact path + provenance (`ResolvedSessionArtifact`);
- runtime catalog entries for built-ins and configured artifacts;
- requirement sets for canonical previous-session inputs.
- canonical S3 session, run, current, session config, session locks, audio, and promoted artifact keys.

## Boundaries
Owns:
- built-in source registry and validation;
- configured artifact catalog identity (`narratio.artifact.<name>`);
- canonical previous-session source parsing and resolution;
- previous-session requirement collection (`CollectPreviousArtifactRequirements`).

Does not own:
- prepare-stage remote hydration;
- stage success/skip transitions;
- archive upload orchestration.

## Built-in IDs
| Artifact ID | Canonical file | Producer stage | Output kind |
| --- | --- | --- | --- |
| `narratio.transcript.merged` | `transcripts/merged.json` | `merge` | `transcript_merged` |
| `narratio.transcript.polished` | `transcripts/processed.json` | `polish` | `transcript_processed` |
| `narratio.transcript.full` | `transcripts/normalized.json` | `normalize` | `transcript_normalized` |
| `narratio.transcript.trimmed` | `transcripts/trimmed.json` | `trim` | `transcript_trimmed` |
| `narratio.bounds.session` | `artifacts/session_bounds.json` | `trim` | `session_bounds` |

## Source families
- built-in: `narratio.transcript.*`, `narratio.bounds.session`
- configured artifact: `narratio.artifact.<artifact_key>`
- canonical previous-session artifact: `narratio.previous_session.artifact.<artifact_key>`

## S3 key helpers
- session prefix: `{root_prefix}/campaigns/{campaign}/sessions/{session_id}/`
- session config: `{session_prefix}/session.yml`
- session lock store: `{session_prefix}/locks.yml`
- run prefix: `{session_prefix}/runs/{run_id}/`
- audio prefix: `{session_prefix}/{session.inputs.audio_s3.prefix}`
- current manifest: `{session_prefix}/current/manifest.json`
- current run pointer: `{session_prefix}/current/run_id.txt`

## Runtime catalog model
Catalog entries track:
- `planned`: source is registered for this run;
- `executable`: configured artifact is selected for analyze execution;
- `available`: usable local file exists (generated this run or reused from disk).

Configured artifact provenance values include:
- `generated.current_analyze_run`
- `filesystem.disabled_artifact_output`

Previous-session canonical provenance values include:
- `manifest.inputs.previous_cache`
- `current_session.previous_cache`

## Resolution behavior
- Built-ins resolve via manifest producer outputs first, then canonical fallback paths.
- Configured `narratio.artifact.<name>` sources resolve through catalog availability.
- Canonical previous-session sources resolve to current-session `previous/` cache candidates derived from configured artifact canonical output paths.
- Archive-relative configured artifact paths under `artifacts/` are cached without a redundant nested `artifacts/` segment.
- Previous-session canonical resolution prefers manifest-recorded input paths when present, then filesystem fallback under `previous/artifacts/**`.

## Previous-session requirement scanning
`CollectPreviousArtifactRequirements`:
- scans enabled configured artifacts only;
- includes canonical previous-session sources only;
- deduplicates by artifact key;
- merges required/optional references (`required` wins);
- records deterministic sorted source locations for diagnostics.

## Validation behavior
- transcript built-ins: JSON with top-level `segments` array;
- bounds built-in: valid JSON;
- configured and previous-session artifact files: non-empty text content.

## Failure behavior
- unsupported source or malformed canonical previous source: validation/resolution error;
- known source unavailable: `ErrSessionArtifactNotFound`;
- configured/previous canonical source without catalog: error;
- resolved invalid file content: validation error.

## Tests to inspect before changing
- `internal/artifacts/artifact_resolver_test.go`
- `internal/artifacts/catalog_test.go`
- `internal/artifacts/previous_requirements_test.go`
- `internal/stage/prepare_previous_test.go`
- `internal/stage/analyze_test.go`

## Architectural invariants
- Built-in source IDs are static.
- Configured and previous-session source IDs are artifact-key based and validation-gated.
- Resolution behavior remains deterministic and manifest-aware.