# Implementation Plan: Minimal D&D Scene Chunking

Status: Ready for implementation

This plan implements the target state in
[Minimal D&D Scene Chunking](minimal-dnd-scene-chunking.md). Complete the
stages in order. The feature roadmap owns product intent and boundary policy;
this document owns implementation sequence and acceptance criteria.

## Decisions And Constraints

- Keep the production module key `dnd/scenes`, prompt ID `dnd.scenes`, private
  response-schema key and ID, schema filename, schema name, and schema version
  `v1`. This application is pre-release, so update the private v1 contract in
  place rather than adding a second prompt or response decoder.
- The model response contains only a required, non-empty `scenes` array whose
  objects contain exactly `start_unit_id` and `end_unit_id`.
- A newly generated D&D scene plan has no plan-level or range-level
  annotations and no model-derived warnings. Do not retain deprecated fields
  internally, hide them in metadata, or translate them into another free-form
  output.
- Preserve the shared D&D prompt assets, prompt message layout, reference
  slots, configured profile behavior, module registration, structured LLM
  boundary, manifest prompt/schema metadata, and deterministic coverage rules.
- Do not change the generic `source.ChunkPlan`, `source.ChunkRange`, materialized
  chunk, or `source/chunk-map` contracts. Empty annotation maps are already
  valid generic behavior.
- Invalidate all pre-change canonical chunk-plan records once by changing the
  cache record schema from `notarius.chunk-plan.v1` to
  `notarius.chunk-plan.v2`. This is intentionally a global, recoverable
  pre-release cache transition. Do not compare prompt hashes, response-schema
  hashes, chunker keys, profiles, references, or annotations during lookup;
  after the version transition, ADR-0005's source-digest-only reuse policy
  remains unchanged.
- Follow the testing policy: protect the private schema and observable plan
  invariants, remove obsolete annotation tests, and avoid exact prompt-text,
  prompt-length, prompt-hash, or message-count change detectors. Default tests
  remain offline and must not call a live or paid model.
- Do not implement scene-aware combat skipping, ordered dependencies, new
  validators, repair calls, semantic post-processing, or changes to the
  `dnd/scene-descriptions` lane.

## Stage 1: Replace The Scene Chunker With Its Minimal Contract

### Goal

Make every newly generated `dnd/scenes` plan depend only on the model-proposed
scene endpoints and contain no D&D-specific annotations or warnings.

### Production changes

1. Simplify
   `internal/modules/dnd/chunk/scenes/assets/schemas/dnd_scenes.v1.json` in
   place:
   - keep the existing JSON Schema draft and `$id`;
   - retain one top-level object with `additionalProperties: false`;
   - make `scenes` the sole required and permitted top-level field;
   - retain `type: array` and `minItems: 1`; and
   - define each item as a closed object requiring only positive integer
     `start_unit_id` and `end_unit_id`.
2. Rewrite the scene-specific content in
   `internal/modules/dnd/chunk/scenes/assets/prompts/task.md` and
   `instructions.md`:
   - retain the feature roadmap's definition of a scene, positive and negative
     boundary guidance, preference for fewer coherent scenes, and full ordered
     coverage requirement;
   - ask only for inclusive source-unit endpoints;
   - continue to forbid gaps, overlaps, reordering, final chunk IDs, and chunk
     indexes; and
   - remove every request or definition for titles, modes, participants,
     summaries, boundary notes, confidence, and caveats.
   Leave `dnd.scenes.yaml` and the shared prompt assets unchanged. Their
   existing message structure, cache controls, inputs, prompt identity, profile,
   and schema path remain authoritative.
3. Reduce the private DTOs in
   `internal/modules/dnd/chunk/scenes/model.go`:
   - `chunkResponse` contains only `Scenes []sceneResponse`;
   - `sceneResponse` contains only the two existing `shared.UnitRef` endpoint
     fields; and
   - delete `normalizedScene` rather than preserving a second endpoints-only
     representation.
4. Simplify `internal/modules/dnd/chunk/scenes/chunker.go`:
   - remove `annotationNamespace`, annotation JSON encoding, caveat-to-warning
     conversion, semantic field trimming, participant copying, enum helpers,
     and imports used only by those behaviors;
   - keep request validation, source-document validation, prompt inputs,
     response decoding, module registration, reference declarations, and
     manifest metadata unchanged;
   - have `Plan` pass the minimal response to `planFromResponse` and return the
     resulting plan with no warnings;
   - have `planFromResponse` resolve both `shared.UnitRef` endpoints through
     `shared.ResolveUnitID`, validate them against a precomputed map of source
     unit ID to document position, enforce first-to-last contiguous coverage,
     and append ranges containing only `StartUnitID` and `EndUnitID`; and
   - return a plan containing only the source digest and ranges. Treat nil and
     zero-length annotation maps as equivalent absence; do not allocate empty
     maps solely for presentation.
5. Preserve validation by document position. Do not compare endpoint IDs
   numerically or assume that adjacent document units have consecutive IDs.

### Focused tests

Update the existing tests instead of layering parallel coverage onto obsolete
cases:

- In `schema_test.go`, make the valid fixture use only the minimal fields.
  Retain schema identity/loading and defensive-copy coverage. Verify a valid
  minimal response, a missing or empty `scenes` array, non-positive or
  non-integer endpoints, unknown top-level fields, and unknown scene fields.
  A removed legacy field is sufficient to exercise scene-level unknown-field
  rejection; do not enumerate every removed field.
- In `chunker_test.go`, replace
  `TestPlanReturnsSceneRangesAndAnnotationsFromStructuredOutput` with a
  behavior-level test that verifies the structured request, exact resolved
  ranges, source digest, absent plan/range annotations, and absent warnings.
  Remove the whitespace-caveat and annotation-defensive-copy tests and remove
  obsolete semantic-field cases from the malformed-output table.
- Retain request, reference-input, legacy-roster mapping, LLM error, module
  registration, manifest metadata, missing/empty scene, unknown endpoint,
  reversed endpoint, gap, overlap, and incomplete-coverage behavior.
- Add one planner case whose source units have positive IDs in a nonnumeric
  document order, such as `10, 3, 20`. Prove that valid ranges follow document
  order and that reversal is judged by positions rather than numeric values.
- Simplify test builders such as `scene`, `validSceneResponse`, and schema
  fixtures so they construct only endpoints.
- Keep the prompt preparation and diagnostics tests in
  `scriptorium_assets_test.go`. Preparation through the real embedded assets is
  sufficient; do not assert the exact wording or hash of the rewritten
  scene-specific prompt.

### Stage validation

Run:

```sh
gofmt -w internal/modules/dnd/chunk/scenes/*.go
go test -count=1 ./internal/modules/dnd/chunk/scenes
git diff --check
```

Stage 1 is complete when the focused package accepts the minimal structured
response, rejects malformed ranges, returns annotation-free and warning-free
plans, and contains no production references to the removed response fields.

## Stage 2: Retire Old Cached Plans And Align Maintained Contracts

### Goal

Ensure a pre-change cached plan cannot reintroduce removed D&D annotations,
while preserving generic annotations and source-addressed plan reuse for all
new records.

### Cache compatibility changes

1. Change `pipeline.ChunkPlanSchemaVersion` in
   `internal/framework/pipeline/chunk_plan_store.go` from
   `notarius.chunk-plan.v1` to `notarius.chunk-plan.v2`.
2. Do not add a v1 decoder, migration, deletion routine, or D&D-specific cache
   branch. `internal/framework/chunkplan` must continue treating a schema
   mismatch as a recoverable invalid record. In `auto` mode the existing runner
   path then regenerates and atomically replaces it; `refresh` and `bypass`
   retain their existing meanings.
3. Update `internal/framework/chunkplan/store_test.go` so its valid records use
   v2 and its invalid-record table explicitly proves that a well-formed v1
   record is reported as invalid/recoverable. It is appropriate to assert both
   version literals here because this test owns a deliberate wire
   compatibility transition.
4. Preserve existing runner tests proving that valid current-version plans are
   reused across chunker or configuration differences and that structurally
   invalid hits regenerate. Do not add a second runner test that merely repeats
   the store's schema-version rejection and the runner's existing invalid-hit
   behavior.

### Generic fixture cleanup

The generic chunk-map codec must continue exercising arbitrary annotations,
but its fixtures should not imply that the minimal `dnd/scenes` producer still
emits them:

1. In `internal/framework/chunkmap/codec_test.go` and
   `internal/framework/chunkmap/testdata/source_chunk_map.v1.json`, replace the
   illustrative D&D identities and semantic scene values with neutral test
   data. Use `chunk/requested` as the requested chunker, `chunk/producer` as the
   producer, and `test/chunker` as the annotation namespace; retain small JSON
   objects as annotation values so canonicalization remains exercised.
2. Preserve all existing annotation canonicalization, strict decoding,
   defensive ownership, digest, and round-trip assertions. Do not remove
   generic annotation coverage or change the durable chunk-map schema.
3. Retain the distinct requested and producing chunker identities to exercise
   ADR-0005 reuse without associating generic annotation behavior with a
   production module.

### Documentation and roadmap alignment

1. Update only the canonical current-behavior documentation that becomes
   inaccurate:
   - revise the `internal/modules/dnd/chunk/scenes` section of
     `docs/internal/modules.md` to describe the boundary-only response,
     deterministic coverage validation, annotation-free plan, and absence of
     boundary warnings;
   - in `docs/roadmap/future.md`, remove the completed chunker-minimization
     bullet and rename `Minimize And Use D&D Scene Chunking` to `Use D&D Scene
     Chunking`, retaining its still-future combat gating, ordered dependency,
     and reassessment work; and
   - set the feature roadmap status to `Implemented` only after all production,
     test, and current-documentation changes pass.
2. Do not change `docs/integrations/chunk-map.md`: it already owns the unchanged
   generic artifact contract, permits empty maps, and correctly treats
   annotations as optional module-specific JSON.
3. Do not change configuration, CLI, operations, LLM runtime, or
   scene-description integration documentation unless implementation reveals a
   statement that is factually false after this work. Those documents do not
   own the removed private response fields.
4. Do not add live-model evaluation to the offline suite. At handoff, recommend
   evaluating the simpler prompt against the human-reviewed cases described in
   the feature roadmap; credentials and human quality judgment are not
   implementation completion gates.

### Stage validation

Run focused checks first:

```sh
go test -count=1 ./internal/modules/dnd/chunk/scenes
go test -count=1 ./internal/framework/chunkplan
go test -count=1 ./internal/framework/chunkmap
go test -count=1 ./internal/framework/pipeline
```

Then run the repository-wide checks required for shared contracts:

```sh
gofmt -w internal/modules/dnd/chunk/scenes/*.go \
  internal/framework/chunkplan/*.go \
  internal/framework/chunkmap/*.go \
  internal/framework/pipeline/chunk_plan_store.go
go test -count=1 ./...
go vet ./...
go build ./cmd/notarius
git diff --check
```

Review the final diff and confirm:

- only endpoint fields remain in the private response, prompt instructions,
  DTOs, and focused fixtures;
- newly generated D&D scene plans have no annotations or warnings;
- v1 cache records are recoverably invalid and new records use v2;
- valid v2 plans still follow source-only canonical reuse;
- generic chunk-map annotations remain supported;
- no current-behavior document claims that `dnd/scenes` produces semantic
  annotations; and
- no scene-aware combat or ordered-dependency work entered the change.

## Open Questions

None. The feature and migration choices are decision-complete.