# Internal: Artifacts

## Purpose
Describe supported session artifact IDs, transcript tiers, and artifact resolution/provenance behavior used by stage logic and Scriptorium input configuration.

## Inputs and outputs
Inputs:
- Artifact source identifiers from stage config/runtime (for example `pipeline.scriptorium.artifacts.*.inputs.*.source`).
- Session paths and optional session manifest stage outputs.

Outputs:
- Resolved local artifact path + provenance (`ResolvedSessionArtifact`).
- Validation errors for unsupported or unreadable artifact sources.

## Boundaries
Owns:
- Canonical artifact ID registry and metadata (`internal/artifacts/artifact_resolver.go`).
- Alias normalization for legacy source names.
- Resolution order and artifact content validation.

Does not own:
- Artifact generation (stages produce files).
- Manifest transition policy.
- Remote archive publishing behavior.

## Config fields used
Artifact source usage is driven by:
- `pipeline.scriptorium.artifacts.<name>.inputs.<key>.source`
- Optional source-specific fields for previous artifact input (`artifact`, `path`, `required`).

## External adapters used
- No external service adapters.
- Resolver relies on local filesystem checks + session manifest state.

## State and manifest behavior
Supported canonical IDs and current mappings:

| 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` |
| `narratio.artifact.session_recap` | `artifacts/session_recap.md` | `analyze` | `session_recap` |

Resolution order:
1. Session manifest producer-stage outputs (if readable/valid).
2. Canonical session path fallback.

Provenance fields:
- `ProducerStage`
- `OutputKind`
- `ProducerRunID` (when resolved from manifest output)
- `Provenance` (`manifest.<stage>.outputs` or `fallback.canonical_path`)

Content validation by artifact type:
- Transcript artifacts: JSON with top-level `segments` array.
- `narratio.bounds.session`: valid JSON.
- `narratio.artifact.session_recap`: non-empty text.

## Skip and resume behavior
- Resolver has no direct skip/resume logic.
- Resolver output influences stage behavior (for example analyze input resolution and required-input failures).

## Failure behavior
- Unsupported or empty artifact source -> normalization error.
- Known source not found/readable -> `ErrSessionArtifactNotFound` wrapped error.
- Found but invalid content -> validation error.

## Tests to inspect before changing
- `internal/artifacts/artifact_resolver_test.go`
- `internal/artifacts/resolve_test.go`
- `internal/stage/analyze_test.go`
- `internal/config/scriptorium_test.go`

## Architectural invariants
- Artifact IDs are canonical interface values for stage/config integration.
- Alias support is compatibility behavior layered on top of canonical IDs.
- Manifest producer outputs are preferred over canonical fallback when both exist.