Stage 2, items 1, 4, and 5 of `plan/17-refactor.md`.
**One path resolver in `worldstate`.** `apply_delta` and `apply_override` routed
`flags.<name>`, `milestones.<id>`, `world.<stat>`, `player.<stat>`, and
`npc.<id>.<stat>` with parallel code, about 100 lines each. `_resolve` now says
what a path points at and returns either a target or the rejection to report.
Each function keeps its own write rule, because the rules genuinely differ: an
override sets a number rather than adding to it, ignores `cooldown`,
`max_delta_per_turn`, and the rule that a counter only counts up, and can un-set
a milestone.
A differential check ran both implementations over 3960 payloads: twenty paths,
fourteen values, three starting states, plus every three-path combination. The
results are identical except that 674 rejections from `apply_override` now carry
a `fix` string. `apply_delta` already worded those, and the world-state editor
renders them, so an override that names an unknown flag now explains itself the
way a delta does.
**`sse`, `SSE_HEADERS`, and `turn_error` move to `app/sse.py`.** Two routers
stream, and `chat.py` had to import from `routers.adventures` to reach them.
**`get_adventure_or_404` becomes the `current_adventure` dependency.** All 32
handlers repeated the call as their first statement. The ownership check now
reads in the signature and runs before the body. FastAPI caches a dependency for
one request, so the handler's `db` is the session the adventure came from.
The generated OpenAPI document is byte-identical except on `rename_branch`,
where `branch_id` is now listed before `adventure_id`, because that handler no
longer names `adventure_id` itself. Parameter order in the document is
cosmetic.
Six tests in `test_state_revert.py` call `undo_turn` and `retry_action`
directly rather than over HTTP. They pass the adventure they already hold
instead of an id.
549 tests pass.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014Dix4oGV3njgWRdu7P9t6r
