> For the complete documentation index, see [llms.txt](https://ai-os-and-trend-finder.gitbook.io/ai-os-and-trend-finder-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ai-os-and-trend-finder.gitbook.io/ai-os-and-trend-finder-docs/.spec_system/archive/phases/phase_39/session_04_existing_media_floor_four.md).

# Session 04: Existing-Media Floor Four

**Session ID**: `phase39-session04-existing-media-floor-four` **Status**: Not Started **Estimated Tasks**: \~12-25 **Estimated Duration**: 2-4 hours

***

## Objective

Prove level authoring is now mostly data by adding a fourth floor that reuses existing media and IDs.

***

## Scope

### In Scope (MVP)

* Append one `AiRogueLevelSpec` for depth 4.
* Reuse an existing theme such as `firewall` or `model-vault` and document why that reuse is intentional.
* Reuse existing enemies, prefabs, terminals, protocols, music, ambience, and frames.
* Define the floor label, lesson, enemy table, guard, prefab, terminal or protocol choices, objective, reward profile, and generation profile.
* Add deterministic generation and simulation tests for depth 4, including reachable exit, no spawn overlap, guard placement, objective lock or unlock, and save round-trip behavior.

### Out of Scope

* Adding new monsters, bosses, music, ambience, assets, or save IDs.
* Adding renderer, audio switch, simulation, or route-import branches for the new floor.

***

## Detailed Plan Notes

* This session proves the workflow with a level that reuses existing media before new enemies, new bosses, or new music are attempted.
* The new floor should be authored by appending one `AiRogueLevelSpec` to `content/levels.ts`.
* The reused theme, such as `firewall` or `model-vault`, must have a documented rationale so it reads as intentional rather than an accidental repeat.
* Reuse existing enemies, prefabs, terminals, protocols, music, ambience, and frames.
* The floor still needs a distinct label, lesson, enemy table, guard, prefab, terminal/protocol choice, objective, reward profile, and generation profile.
* Deterministic tests must cover reachable exit, no spawn overlap, guard placement, objective lock/unlock if used, and save round-trip coverage.
* A depth-4 run should round-trip through `save-schema.ts` without a schema version bump when it only reuses existing persisted IDs.

***

## Prerequisites

* [ ] Sessions 01-03 are complete.
* [ ] Registry and save parity gates are active.

***

## Deliverables

1. A playable fourth floor backed by one level spec and focused tests.
2. Save round-trip proof for a depth-4 run that only reuses existing persisted IDs.
3. Updated evidence that max depth increases from authored content rather than a standalone constant.

***

## Success Criteria

* [ ] The playable max depth increases from three to four by adding the level spec.
* [ ] No renderer branch, audio switch branch, simulation branch, route import, or save-schema edit is needed unless a newly persisted ID is introduced.
* [ ] Existing and new depth tests pass.
* [ ] Depth 4 proves max depth increased from authored content rather than a standalone constant.


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