feat(#18): affect.fetch — adopt bifrost 0.10.0 mandatory fetch (D1 prerequisite)

bifrost 0.10.0's _supports_affect_plane (bifrost/affect.py:75-80) now requires a
callable fetch for the affect capability to advertise/dispatch at all (INV-012
strong-or-absent), so an emit-only store 400s on EVERY affect op — repinning past
the affect.fetch release (#12/#13) breaks our shipped affect plane until fetch
exists. Implement affect.fetch as a thin async wrapper over the existing get()
read seam, conformed verbatim to the reference InMemoryAffectStore.fetch:
{"found": False} or {"found": True, "snapshot": <verbatim>}, AffectInvalidArguments
on empty ids, opaque (INV-001 — never reads pad/valence).

This is the forced prerequisite for the #18 D1 composite (build_combined_app),
and a new Worldtree I/O point consumed (affect read-back over bifrost).

- Repin bifrost>=0.8.0 -> >=0.10.0 (uv lock: 0.8.0 -> 0.10.0)
- affect_store.py: add async fetch() over get()
- contract bifrost_affect_provider v1.2: fetch FN block + INV-010 (cap = supported+emit+fetch)
- tests: 3 fetch unit + parity_vs_reference_fetch through dispatch_affect_call
- suite 482 -> 486 green

docs/contracts/bifrost_affect_provider.contract.md

@@ -10,7 +10,7 @@ complexity: "medium"
 estimated_loc: 180
 confidence: 0.85
 assumptions:
-  - "bifrost>=0.6.1 is installed and exposes build_affect_app, dispatch_affect_call, JwtVerifier, ConsumerRegistration, AffectInvalidArguments, AffectIdempotencyConflict per bifrost/docs/implementing-a-consumer.md @ 8df54ed and bifrost/reference_server/affect.py."
+  - "bifrost>=0.10.0 is installed and exposes build_affect_app, build_combined_app, dispatch_affect_call, JwtVerifier, ConsumerRegistration, AffectInvalidArguments, AffectIdempotencyConflict, and REQUIRES a callable affect-store fetch for the affect capability (_supports_affect_plane, bifrost/affect.py:75-80, strong-or-absent) per bifrost/reference_server/affect.py."
   - "The affect snapshot dict always carries string addressing keys 'agent_id' and 'end_user_id'; the bifrost wire validates the envelope before the store is called."
   - "A Heimdall HS256 key for consumer_id='ratatoskr' is provisioned (deploy-time, brokered via infra-ops); the store itself never sees raw auth — the library verifies per-dispatch JWTs and hands a DispatchContext (ctx)."
   - "The idempotency actor is derivable from ctx (mirrors bifrost's reference `_ctx_actor(ctx)` — the dispatch subject/actor identity)."
@@ -21,7 +21,9 @@ external_invariants:
   - source: ~/development/bifrost/docs/contracts/affect.contract.md
     invariant_id: "INV-001"          # conduit opacity — the governing rule of the affect plane
   - source: ~/development/bifrost/bifrost/reference_server/affect.py
-    invariant_id: "InMemoryAffectStore.emit"   # the executable reference for the wire semantics we parity-prove against
+    invariant_id: "InMemoryAffectStore.emit"   # the executable reference for the emit wire semantics we parity-prove against
+  - source: ~/development/bifrost/bifrost/reference_server/affect.py
+    invariant_id: "InMemoryAffectStore.fetch"  # the executable reference for the affect.fetch read shape ({found, snapshot})
 revisions:
   - version: "1.1"
     at: 2026-06-14
@@ -39,6 +41,22 @@ revisions:
         - "basic_emit wording — semantic round-trip (was: byte-identical)"
       REMOVED:
         - "the 'same idempotency_key + different content hash -> LWW overwrite' clause (it was backwards: bifrost treats that as a conflict)"
+  - version: "1.2"
+    at: 2026-06-19
+    summary: "Adopt bifrost 0.10.0's mandatory affect.fetch (strong-or-absent, INV-012): _supports_affect_plane now requires a callable fetch for the affect cap to advertise/dispatch at all, so an emit-only store 400s on EVERY affect op. Promote the sync get() read seam to an async wire fetch() returning bifrost's {found, snapshot} shape; conform to the reference InMemoryAffectStore.fetch. affect.fetch leaves 'reserved'. Forced prerequisite of the #18 D1 composite (build_combined_app)."
+    delta:
+      ADDED:
+        - "fetch() function block (async wire verb; mirrors reference InMemoryAffectStore.fetch)"
+        - "INV-010 (affect cap = affect_supported + emit + fetch, strong-or-absent)"
+        - "parity_vs_reference_fetch test"
+        - "InMemoryAffectStore.fetch external invariant"
+      MODIFIED:
+        - "INV-005 — cross-refs INV-010 (the affect cap now requires fetch present too)"
+        - "assumptions — bifrost pin >=0.10.0 (build_combined_app + mandatory affect.fetch)"
+        - "get() BRIEF — the sync read seam fetch() wraps (no longer 'affect.fetch RESERVED')"
+        - "Data flow — add the fetch read-back path"
+      REMOVED:
+        - "the 'affect.fetch / affect:read RESERVED in v1' out-of-scope line"
 ---
 
 ## Context
@@ -75,13 +93,19 @@ affect; we only persist and round-trip it.** We run no affect logic.
     conflict cache: `digest` is a content fingerprint of the snapshot;
     `expires_at` records the short-retry deadline for a future pruning pass
     (TTL eviction deferred — see INV-009).
-- **Out:** `{"stored": True}` ack (the library wraps it with the transport
+- **Out (emit):** `{"stored": True}` ack (the library wraps it with the transport
   `{"success": True}` envelope).
+- **Fetch (read-back):** Worldtree's `affect.fetch` → `POST /bifrost/affect-call`
+  → `store.fetch(agent_id=..., end_user_id=...)` → `{"found": False}` or
+  `{"found": True, "snapshot": <verbatim snapshot>}` (the library wraps it via
+  `affect_result(**fetched)`). The snapshot is returned opaque/verbatim — `fetch`
+  never reads `pad` / `valence` / `persona_baselines` / `emitted_at` (INV-001).
 
-**Async surface:** `emit` is `async def` (the bifrost consumer Protocol awaits
+**Async surface:** `emit` and `fetch` are `async def` (the bifrost consumer
-it); `open_affect_store` and `get` are sync (no I/O await — `get` is a read-back
+Protocol awaits them); `open_affect_store` and `get` are sync (no I/O await —
-seam). The `FN` lines below omit the `async` keyword only because the contract
+`get` is the read-back seam `fetch` wraps). The `FN` lines below omit the
-grammar's `FN <name>` form has no async marker.
+`async` keyword only because the contract grammar's `FN <name>` form has no
+async marker.
 
 ## Invariants
 
@@ -113,7 +137,7 @@ grammar's `FN <name>` form has no async marker.
   `stored` specifically).
 - **INV-005** [hard]: The store advertises `affect_supported = True`; it is the
   REQUIRED store — `build_affect_app(store=None, ...)` raises (no silent
-  in-memory default).
+  in-memory default). See INV-010 for the full affect-capability surface.
 - **INV-006** [hard]: Authorization identity/scope — and the **idempotency
   actor** — are taken from `ctx` (DispatchContext), never from the snapshot or
   other call arguments. The snapshot addressing keys are used ONLY as the
@@ -137,6 +161,13 @@ grammar's `FN <name>` form has no async marker.
   grows unbounded until a follow-up pruning patch. Wire-observable behavior is
   unaffected (replay/conflict still resolve correctly); only cache size is.
   `affect_snapshots` is already bounded to one row per `(agent_id, end_user_id)`.
+- **INV-010** [hard]: **The affect capability is `affect_supported` + `emit` +
+  `fetch`, strong-or-absent** (bifrost ≥0.10.0 `_supports_affect_plane`,
+  `bifrost/affect.py:75-80`; the INV-012 no-degraded-path rule). bifrost gates
+  EVERY affect op (emit included) on all three being present, so a store missing
+  a callable `fetch` is rejected with `affect.unsupported_capability` and the
+  handshake never advertises `affect`. We therefore implement `fetch` fully (not
+  a stub) — the canonical surface admits no emit-only affect store.
 
 ## Concurrency
 
@@ -186,8 +217,10 @@ already have rejected a malformed envelope.
   Protocol are a later contract.
 - **The combined two-plane server** (guide §7): one handshake negotiating both
   memory + affect is deferred; `build_affect_provider_app` mounts affect alone.
-- **`affect.fetch` / `affect:read` / persona-baseline rehydrate**: RESERVED in
+- **`affect:read` scope enforcement / persona-baseline rehydrate shaping**: the
-  v1; only `emit` + the test-only `get()` exist.
+  library owns scope auth (`affect:read` for fetch); `fetch` returns the stored
+  blob verbatim — any richer rehydrate shaping beyond a snapshot round-trip is
+  Worldtree's concern, not the store's.
 - **`idempotency_class`**: accepted and ignored (affect.* uses a single
   short-retry class).
 - **WAL/concurrency hardening, deployment DB path, auth-key provisioning**:
@@ -254,7 +287,7 @@ TESTS:
 
 ```contract
 FN get(self, agent_id: str, end_user_id: str) -> dict | None
-BRIEF: Read-back of the stored snapshot (tests / future rehydrate-seed). NOT a wire verb — affect.fetch is RESERVED in v1.
+BRIEF: Sync read-back seam returning the verbatim stored snapshot (or None). The async wire verb fetch() wraps this; tests / the D2 read route / rehydrate-seed also use it directly.
 POST: [POST-001 return_value] returns the verbatim snapshot for the key, or None if absent -- (INV-003)
 STEPS:
   1. [sequential] SELECT snapshot_json FROM affect_snapshots WHERE agent_id = ? AND end_user_id = ?
@@ -264,6 +297,30 @@ TESTS:
   get_after_emit [happy]: returns the emitted snapshot, deserialized equal
 ```
 
+```contract
+FN fetch(self, agent_id: str, end_user_id: str) -> dict
+BRIEF: Wire affect.fetch read handler — return the stored snapshot in bifrost's {found, snapshot} shape, conduit-opaque. Mirrors the reference InMemoryAffectStore.fetch verbatim (INV-010 strong-or-absent: this method MUST exist for the affect cap to advertise/dispatch).
+PRE: [PRE-001 hard] agent_id and end_user_id are non-empty strings -- else raise AffectInvalidArguments (mirrors reference; the wire validates the envelope first, this is belt-and-suspenders)
+POST: [POST-001 return_value] returns {"found": False} when no snapshot for the key -- (the library wraps via affect_result(**fetched))
+POST: [POST-002 return_value] returns {"found": True, "snapshot": <verbatim snapshot>} when present; snapshot deserializes equal to the emitted snapshot -- (INV-003)
+POST: [POST-003 return_value] never reads pad/valence/persona_baselines/emitted_at — returns the whole blob opaque -- (INV-001)
+ERROR_ROUTING:
+  AffectInvalidArguments:
+    local_handling: raise on missing/empty agent_id or end_user_id
+    flow_control: abort
+    state_recovery: none (read-only; no state touched)
+STEPS:
+  1. [setup, flexibility=prescriptive] IF agent_id/end_user_id missing or not non-empty str: RAISE AffectInvalidArguments
+  2. [sequential] SET snap = self.get(agent_id, end_user_id)  -- the existing sync read seam; whole-blob json.loads, no field reads (INV-001)
+  3. [branch] IF snap is None: RETURN {"found": False}
+  4. [cleanup] RETURN {"found": True, "snapshot": snap}
+TESTS:
+  fetch_absent [boundary]: no row for key → {"found": False}
+  fetch_after_emit [happy,tracer]: emit then fetch → {"found": True, "snapshot": equals the emitted snapshot}
+  fetch_missing_key [adversarial]: empty/missing agent_id or end_user_id → raises AffectInvalidArguments
+  parity_vs_reference_fetch [scenario]: drive identical affect.fetch envelopes (found + not-found) through dispatch_affect_call against InMemoryAffectStore and RatatoskrAffectStore → (status, body) tuples agree (#195)
+```
+
 ```contract
 FN build_affect_provider_app(store: RatatoskrAffectStore, heimdall_key: bytes, consumer_id: str = "ratatoskr") -> Starlette
 BRIEF: Wire the JWT verifier + registration and hand the store to bifrost's build_affect_app.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "ratatoskr"
-version = "0.17.14"
+version = "0.17.15"
 description = "Worldtree Conversation API debug TUI — multi-pane observability dashboard"
 readme = "README.md"
 requires-python = ">=3.12"
@@ -30,7 +30,7 @@ web = [
 # from the debug TUI. Recipe: bifrost/docs/implementing-a-consumer.md.
 provider = [
     "ratatoskr[web]",       # reuse the starlette + uvicorn ASGI stack
-    "bifrost>=0.8.0",       # consumer engines + library (0.8.0/wire-v0.6: scope_filter split into scope_all (AND) + scope_any (OR/union, #11); 0.7.0/v0.5 added agent_self)
+    "bifrost>=0.10.0",      # consumer engines + library (0.10.0: build_combined_app (#18) + mandatory affect.fetch, strong-or-absent; 0.8.0/wire-v0.6: scope_all/scope_any split (#11); 0.7.0/v0.5: agent_self)
     "jsonschema>=4",        # bifrost runtime dep — envelope validation
     "sqlite-vec>=0.1.6",    # vector index for the memory plane (vec0 virtual table)
 ]

src/ratatoskr/provider/affect_store.py

@@ -102,13 +102,39 @@ class RatatoskrAffectStore:
         return {"stored": True}
 
     def get(self, agent_id: str, end_user_id: str) -> dict | None:
-        """Read-back of the stored snapshot (tests / future rehydrate-seed)."""
+        """Sync read-back seam returning the verbatim stored snapshot (or None).
+
+        The async wire verb `fetch` wraps this; tests, the D2 read route, and
+        rehydrate-seed also call it directly.
+        """
         row = self._conn.execute(
             "SELECT snapshot_json FROM affect_snapshots WHERE agent_id = ? AND end_user_id = ?",
             (agent_id, end_user_id),
         ).fetchone()
         return json.loads(row[0]) if row is not None else None
 
+    async def fetch(self, agent_id: str, end_user_id: str) -> dict:
+        """Async affect.fetch handler — return the stored snapshot in bifrost's
+        {found, snapshot} shape, conduit-opaque.
+
+        INV-010 (strong-or-absent): bifrost >=0.10.0 gates EVERY affect op on the
+        store advertising affect_supported + emit + fetch (`_supports_affect_plane`),
+        so this method MUST exist for the affect capability to dispatch at all —
+        an emit-only store 400s. Mirrors the reference InMemoryAffectStore.fetch;
+        returns the whole blob opaque (INV-001 — never reads pad/valence).
+        """
+        if not (
+            isinstance(agent_id, str)
+            and agent_id
+            and isinstance(end_user_id, str)
+            and end_user_id
+        ):
+            raise AffectInvalidArguments("fetch missing agent_id / end_user_id")
+        snap = self.get(agent_id, end_user_id)
+        if snap is None:
+            return {"found": False}
+        return {"found": True, "snapshot": snap}
+
 
 def open_affect_store(db_path: str) -> RatatoskrAffectStore:
     """Open the SQLite-backed affect store, creating the schema on first use."""

tests/test_provider_affect.py

@@ -162,6 +162,32 @@ async def test_get_after_emit_returns_equal():
     assert store.get("a1", "u1") == snap
 
 
+# --- fetch (affect.fetch wire verb — bifrost >=0.10.0, INV-010 strong-or-absent) ---
+
+async def test_fetch_absent_returns_found_false():
+    """fetch_absent: no row for the key → {"found": False} (mirrors reference)."""
+    store = open_affect_store(":memory:")
+    assert await store.fetch("nope", "nope") == {"found": False}
+
+
+async def test_fetch_after_emit_returns_snapshot():
+    """fetch_after_emit [tracer]: emit then fetch → {"found": True, "snapshot": <verbatim>}."""
+    store = open_affect_store(":memory:")
+    snap = _snapshot()
+    await store.emit(snap, idempotency_key="k1", ctx=_ctx())
+    assert await store.fetch("a1", "u1") == {"found": True, "snapshot": snap}
+
+
+async def test_fetch_missing_key_raises():
+    """fetch_missing_key: empty/missing addressing key → AffectInvalidArguments
+    (PRE-001; symmetric across both keys, belt-and-suspenders behind the wire)."""
+    store = open_affect_store(":memory:")
+    with pytest.raises(AffectInvalidArguments):
+        await store.fetch("", "u1")
+    with pytest.raises(AffectInvalidArguments):
+        await store.fetch("a1", "")
+
+
 # --- build_affect_provider_app ---
 
 def test_build_app_exposes_handshake_and_affect_routes():
@@ -243,6 +269,36 @@ async def test_parity_vs_reference_store_through_dispatch():
     )
 
 
+def _fetch_env(agent_id: str = "agent-1", end_user_id: str = "user-1") -> dict:
+    return {"operation": "affect.fetch", "args": {"agent_id": agent_id, "end_user_id": end_user_id}}
+
+
+async def test_parity_vs_reference_fetch_through_dispatch():
+    """#195 parity for affect.fetch: cold (not-found) + warm (found) read envelopes
+    yield identical (status, body) through the real engine against the reference store
+    and ours. Conforms to bifrost's InMemoryAffectStore.fetch ({found, snapshot})."""
+    from bifrost.affect import dispatch_affect_call
+    from bifrost.consumer.testing import InMemoryAffectStore
+
+    ref = InMemoryAffectStore()
+    mine = open_affect_store(":memory:")
+    write_ctx = _dispatch_ctx("affect:write")
+    read_ctx = _dispatch_ctx("affect:read")
+
+    # cold fetch (nothing persisted): both -> {found: false}
+    assert await dispatch_affect_call(_fetch_env(), read_ctx, ref) == await dispatch_affect_call(
+        _fetch_env(), read_ctx, mine
+    )
+
+    # seed both via emit, then fetch -> both {found: true, snapshot: <verbatim>}
+    snap = _ref_shaped_snapshot()
+    await dispatch_affect_call(_env(snap), write_ctx, ref)
+    await dispatch_affect_call(_env(snap), write_ctx, mine)
+    assert await dispatch_affect_call(_fetch_env(), read_ctx, ref) == await dispatch_affect_call(
+        _fetch_env(), read_ctx, mine
+    )
+
+
 # --- PAD read route (issue #18 Deliverable 2) ---
 # Non-bifrost GET /affect/state/{agent_id}?end_user_id=… → store.get snapshot.
 

uv.lock

@@ -190,14 +190,14 @@ wheels = [
 
 [[package]]
 name = "bifrost"
-version = "0.8.0"
+version = "0.10.0"
 source = { registry = "https://gitea.phasefinal.com/api/packages/vh/pypi/simple/" }
 dependencies = [
     { name = "jsonschema" },
 ]
-sdist = { url = "https://gitea.phasefinal.com/api/packages/vh/pypi/files/bifrost/0.8.0/bifrost-0.8.0.tar.gz", hash = "sha256:28194877c81a056a0803b052e86902c092e965d4ce63a5623d7a31240cedb645" }
+sdist = { url = "https://gitea.phasefinal.com/api/packages/vh/pypi/files/bifrost/0.10.0/bifrost-0.10.0.tar.gz", hash = "sha256:aba1869dba68d921f2e0be8fb560277073da09ec2ad5f410e226cacd5e84fe1a" }
 wheels = [
-    { url = "https://gitea.phasefinal.com/api/packages/vh/pypi/files/bifrost/0.8.0/bifrost-0.8.0-py3-none-any.whl", hash = "sha256:2aac5e4a7828d718389748a78dae6baeb5e9ee4a801a10c427c06c5cc7ed6597" },
+    { url = "https://gitea.phasefinal.com/api/packages/vh/pypi/files/bifrost/0.10.0/bifrost-0.10.0-py3-none-any.whl", hash = "sha256:88adbce23fa8840a14f9493e4f0cf6f9320f4950845f7a6080387defe574a5cc" },
 ]
 
 [[package]]
@@ -1052,7 +1052,7 @@ wheels = [
 
 [[package]]
 name = "ratatoskr"
-version = "0.17.14"
+version = "0.17.15"
 source = { editable = "." }
 dependencies = [
     { name = "httpx" },
@@ -1086,7 +1086,7 @@ web = [
 
 [package.metadata]
 requires-dist = [
-    { name = "bifrost", marker = "extra == 'provider'", specifier = ">=0.8.0", index = "https://gitea.phasefinal.com/api/packages/vh/pypi/simple/" },
+    { name = "bifrost", marker = "extra == 'provider'", specifier = ">=0.10.0", index = "https://gitea.phasefinal.com/api/packages/vh/pypi/simple/" },
     { name = "httpx", specifier = ">=0.27" },
     { name = "httpx-sse", specifier = ">=0.4" },
     { name = "jsonschema", marker = "extra == 'provider'", specifier = ">=4" },