# worldtree-sdk cutover — SLICE-7 (teardown, the LAST slice) COMPLETE

`[2026-07-19]` Commit `ec68b1f` `feat(#20): worldtree-sdk cutover teardown (slice-7) + v0.22.0`,
tag **v0.22.0** (lightweight). Closes issue #20's implementation: all 7 slices done, suite **494 green**.
This slice is **teardown only — zero runtime-logic change**; the green suite is the regression gate.

## What slice-7 did

1. **Dropped `httpx-sse`** from `pyproject.toml` + lockfile. Slice-6 deleted its last user
   (`sse_client.stream_admin_events`); a tree grep confirmed nothing imports `httpx_sse`. `uv sync`
   physically pruned it from the venv; suite green with the module absent (empirical safety proof — a
   heid bug-hunt would find nothing on a proven-unused dep removal, so it was skipped with that reasoning).
2. **Module-boundary decision — KEEP (operator decision A1, surfaced via /elitk + AskUserQuestion).**
   Post-cutover `sessions.py` (227 LOC) and `sse_client.py` (170 LOC) hold NO client — only ratatoskr's
   caller-semantic exception surface + a couple of dataclasses (`BifrostBinding`; `SseId`, `AdminEvent`) +
   the `endpoint_for_plane` provider helper. Three options weighed:
   - **A1 (chosen)** — keep as-is, fix the misleading docstrings. Zero import churn, zero risk.
   - A2 — rename to `session_errors.py`/`stream_errors.py`, re-point ~7 importers. Honest names but pure
     polish nobody asked for, right before a milestone.
   - A3 — consolidate into one `errors.py` / fold into `wt.py`. **Blocked** by the `AgentNotAvailable`
     name collision (two distinct classes: persona-404 in `sessions` vs eager-turn-409 in `sse_client`)
     which would force renaming a contract-level caller-semantic type + its §Error-map rows + all catch
     sites; folding into `wt.py` also mis-homes `endpoint_for_plane` (provider-side) and balloons the
     adapter. Naming-honesty (principle-2) addressed by a one-line docstring note instead.
   - **Resolves the slice-6 deferred item** (contract line ~326): the ratatoskr `AdminEvent`/`SseId` +
     exceptions stay in `sse_client.py`; the session/tier3 exceptions + `BifrostBinding` stay in `sessions.py`.
   - The class-identity foot-gun holds: exception homes must never be run as `__main__` (else a `-m` CLI's
     `except` binds a second copy). `sessions.py`/`sse_client.py`/`wt.py` are all safe; `tier3.py`/`cli.py` are not.
3. **Retired wire contracts #2 (sessions) + #15 (tier3)** — DEC-1 phase-2. Files DELETED
   (`docs/contracts/issues/{2,15}.contract.md`). Their normative authority transferred to the cutover
   contract at authoring; the code they specified is gone. **#1 (SSE event vocabulary) NOT retired** —
   stays current (amended `4bd9abd` 2026-07-18) as ratatoskr's SSE-rendering reference; **`first_message`
   NOT retired** (ratatoskr-owned usage contract). **Accepted side-effect:** `issues/5.contract.md`'s
   historical "amended #2/#3/#4 in-place" line now points at a deleted #2 — left as-is (frozen issue-record
   of a past action; NOT expanding DEC-1's #2/#15 retirement scope, which was heid-reviewed + operator-set).
4. **Final coverage-map re-anchor.** `GET /sessions/{id}/tools` → `wt.py get_session_tools` (SDK
   `sessions.tools`) → `web/server.py` (old `sessions.py`→`tui.py` row was stale; TUI already deleted).
   `list_sessions` re-homed to `wt.py`, still caller-less (picker was a TUI frontier, now moot). The
   `Last-Event-ID` SSE-resume sub-gap CLOSED — `reconnect_turn` deleted, resume folded into `wt.py
   stream_turn` auto-resume. Surface-2 SSE parsing re-anchored to the SDK (`_envelope_for_type` gone).
5. **Stale doc-rot fix** — the `cli.py` transport comment no longer calls `seed_preset_first_message`
   "not-yet-migrated hand-rolled" (it rides `wt.write_authored_history` since slice-3).
6. **v0.22.0** (minor, DEC-6, operator-approved 2026-07-19) — publishes the full 6-slice cutover milestone.

## Verification

- Suite **494 green** (clean env: `env -u RATATOSKR_ADMIN_API_KEY -u RATATOSKR_API_KEY -u WORLDTREE_API_KEY`
  or venv-active with those keys unset).
- `httpx_sse` gone from the venv (`import httpx_sse` → ModuleNotFoundError); 0 refs in `uv.lock`; 0 in `src/`.
- Cutover contract still validates (only the expected no-FN-block warnings for a migration contract).
- No residual hand-rolled consumer HTTP paths: every `httpx.AsyncClient` construction outside `wt.py`
  (cli/tier3/web/entrypoint) feeds `wt.build_client(transport=…)` per INV-CUT-1; zero raw `.get`/`.post`
  bypass calls. Bifrost PROVIDER planes stay hand-rolled (INV-CUT-3, untouched).

## Pending (non-blocking, operator's call)

- `git push` origin — `ec68b1f` + the **v0.22.0 tag are LOCAL only**.
- althing announce of v0.22.0 to worldtree-dev / wtsdk-dev per the SemVer push-notify (post-push; Rata is
  the SDK reference consumer, wt #371).

## Discovered during the slice (not bugs)

- Phantom stale-LSP diagnostics flagged `test_sse_client.py` + `slice6_smoke.py` — neither exists on disk
  or in git (both deleted in slice-6). The in-venv 494-green suite is authoritative over Pyright, which
  resolves against system Python (all the `worldtree_sdk`/`starlette`/`respx` "unresolved import" noise).

See per-slice arc files `[[2026-07-19-worldtree-sdk-cutover-slice-5-complete]]`,
`[[2026-07-19-worldtree-sdk-cutover-slice-6-complete]]` for the earlier slices; design in auto-memory
`project_worldtree_sdk_cutover`.