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# Implementation Summary

**Session ID**: `phase39-session04-existing-media-floor-four` **Completed**: 2026-06-30 **Duration**: 0.5 hours

***

## Overview

Session 04 proved the Phase 39 authoring workflow by adding an authored fourth AI Rogue floor that reuses existing firewall media, catalog IDs, objective behavior, finale metadata, and browser-local save contracts. Max depth now derives from the four authored level specs, depth 5 remains rejected, and focused tests cover deterministic generation, descent, final victory, objective locks, and save hydration without a schema version bump.

***

## Deliverables

### Files Created

| File | Purpose                                                                             | Lines |
| ---- | ----------------------------------------------------------------------------------- | ----- |
| None | No source files were created; the session extended existing runtime and test files. | 0     |

### Files Modified

| File                                                                   | Changes                                                                                                                  |
| ---------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ |
| `src/extensions/ai-rogue/runtime/content/levels.ts`                    | Added the depth-4 `firewall-gauntlet` level spec, moved authored finale metadata to depth 4, and preserved existing IDs. |
| `src/extensions/ai-rogue/runtime/content/__tests__/levels.test.ts`     | Updated registry expectations for depths 1-4, depth-4 reused-media fields, finale ownership, and depth-5 rejection.      |
| `src/extensions/ai-rogue/runtime/__tests__/content-baseline.test.ts`   | Updated content baseline coverage for max depth 4, helper routing, generation, objective, and reward expectations.       |
| `src/extensions/ai-rogue/runtime/__tests__/depth-resolver.test.ts`     | Shifted authored-depth and fallback assertions now that depth 4 is registry-owned.                                       |
| `src/extensions/ai-rogue/runtime/__tests__/world.test.ts`              | Added depth-4 route-safety, guard, prefab, terminal, vault, and overlap coverage.                                        |
| `src/extensions/ai-rogue/runtime/__tests__/golden-determinism.test.ts` | Extended fixed world and first-turn golden summaries to depth 4.                                                         |
| `src/extensions/ai-rogue/runtime/__tests__/roguelike-loop.test.ts`     | Proved depth 3 descends to depth 4, depth 4 wins, and post-win commands no-op.                                           |
| `src/extensions/ai-rogue/runtime/__tests__/objective-lock.test.ts`     | Added depth-4 objective reset, unlock, and final-victory coverage.                                                       |
| `src/extensions/ai-rogue/__tests__/save-schema.test.ts`                | Added durable snapshot parse and hydration coverage for a depth-4 run while keeping schema version 1.                    |
| `src/extensions/ai-rogue/runtime/__tests__/biome-final.test.ts`        | Kept final-presentation fixtures explicit after authored max depth moved to 4.                                           |
| `.spec_system/state.json`                                              | Marked Session 04 validated and completed, cleared the current session, and recorded workflow history.                   |
| `.spec_system/PRD/phase_39/PRD_phase_39.md`                            | Marked Session 04 complete, advanced progress to 4/8 sessions, and updated the upcoming session.                         |
| `README.md`                                                            | Synced the repository version line to 0.5.93.                                                                            |
| `docs/CHANGELOG.md`                                                    | Added the Session 04 closeout entry.                                                                                     |
| `package.json`                                                         | Incremented patch version from 0.5.92 to 0.5.93.                                                                         |

***

## Technical Decisions

1. **Existing-media proof first**: Depth 4 reuses the current firewall theme, Kernel Sentinel guard and boss, hazard cache prefab, patch mirror terminal, protocol IDs, music, and ambience so the session validates authoring infrastructure before new content expansion.
2. **Finale ownership follows authored max depth**: Depth 3 no longer owns authored finale metadata; depth 4 is the final authored floor while crafted depth-3 presentation fixtures remain explicit in tests.
3. **Save schema stays stable**: Depth-4 save coverage uses existing persisted IDs and schema version 1, with parity tests continuing to guard ID drift.

***

## Test Results

| Metric        | Value         |
| ------------- | ------------- |
| Focused tests | 71 passed     |
| Full tests    | 4642 passed   |
| Typecheck     | PASS          |
| Lint          | PASS          |
| Coverage      | Not collected |

***

## Lessons Learned

1. A reused-media floor is a useful pressure test for registry ownership because it exercises routing, validation, objective, finale, and save contracts without new asset variables.
2. Golden determinism needs both world-shape and first-turn run summaries when max depth changes.
3. Final-presentation fixtures should declare crafted finality explicitly so authored max-depth changes do not blur test intent.

***

## Future Considerations

Items for future sessions:

1. Session 05 should add enemy-family metadata and derived asset checks before new enemy content is authored.
2. Session 06 should move boss and finale behavior toward the planned data-driven contract.
3. Future real-content floors should keep save-schema parity and registry validation as the release gate for new IDs.

***

## Session Statistics

* **Tasks**: 16 completed
* **Files Created**: 0
* **Files Modified**: 15
* **Tests Added**: 11 added or updated cases
* **Blockers**: 0 resolved


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