feat(#20): agents/tier3 family onto the wt adapter + model→role fold (slice-4)

Cut ratatoskr's consumer agent-lifecycle routes over to worldtree-sdk
(issue #20 slice-4). Five routes now flow through `ratatoskr.wt` over the
SDK's `client.agents.*`, returning open-world dicts and mapping the SDK's
undiscriminated `ApiError` floor by route+(status,error_code) per INV-CUT-2:

- `list_agents`      → `agents.list`
- `get_persona_state`→ `agents.persona_state` (404 persona_not_configured /
                        404 agent_not_available / 403 auth_scope_denied)
- `define_agent`     → `agents.define` (429→Tier3QuotaExceeded(retry_after=0),
                        403→Tier3UserIdUnsupported, 422 layer_deferred→…)
- `patch_agent`      → `agents.patch`  (404→Tier3AgentNotFound, 422 field_not_mutable)
- `delete_agent`     → `agents.delete` (404→Tier3AgentNotFound; NOT hide-existence)

Rewired call-sites: the `python -m ratatoskr.tier3` CLI (define/patch/delete)
and the web `_agents_endpoint` / `_persona_state_endpoint`, both catching the
SDK's `ConnectFailed` transport-failure normalization. Deleted the hand-rolled
paths: `sessions.list_agents` / `get_persona_state` / `AgentInfo`, and
`tier3.define/patch/delete_agent` / `Tier3AgentInfo` / parse+extract helpers.

model→role fold (scope B): the define/patch response echoes `role` (spec 1.2 /
b128), read off the open-world dict; `LocalAgentEntry.model`→`.role`,
local-index schema v1→2 (old index discarded, no-backwards-compat).

The Tier-3 caller-semantic exceptions move to `sessions.py`: running the CLI
as `__main__` while `wt` imports `ratatoskr.tier3` bound two copies of each
exception class, so a raised `Tier3AgentNotFound` escaped the CLI's `except`
as an uncaught traceback. Homing them in `sessions` (never `__main__`) makes
the class identity single. The live smoke — not the unit tests, which call
`main()` in-process — caught this.

Error-map rows + slice-4 notes added to the cutover contract; coverage-map
re-anchored. LIVE-SMOKE on personal :8081 (b128): define(thoughtful-character)
→ patch → list(6 agents) → persona_state(→PersonaNotConfigured mapped) →
delete → index empty; non-existent-id patch via `-m` → [agent_not_found]
exit 20. Suite 465 green.

tests/test_sessions.py

@@ -5,10 +5,6 @@ import pytest
 import respx
 
 from ratatoskr.sessions import (
-    AgentInfo,
-    AgentNotAvailable,
-    AuthScopeDenied,
-    PersonaNotConfigured,
     SessionApiFailed,
     create_character,
     delete_character,
@@ -16,9 +12,7 @@ from ratatoskr.sessions import (
     get_capabilities,
     get_character_state,
     get_me,
-    get_persona_state,
     get_session_bifrost,
-    list_agents,
     list_character_models,
 )
 
@@ -44,288 +38,6 @@ class TestEndpointForPlane:
             endpoint_for_plane("persona", "10.100.10.50")
 
 
-class TestListAgents:
-    @respx.mock
-    async def test_happy_full_shape(self) -> None:
-        """happy_full_shape [happy,tracer]: spec full-shape mimir example → all fields."""
-        respx.get("https://w.example/agents").mock(
-            return_value=httpx.Response(
-                200,
-                json=[
-                    {
-                        "agent_id": "mimir",
-                        "name": "Mimir",
-                        "description": "Keeper of the Well of Knowledge.",
-                        "version": "0.2.0",
-                        "capabilities": ["knowledge_base", "semantic_search"],
-                        "supported_models": ["default", "heavy"],
-                        "persona_traits": {
-                            "ocean": {
-                                "openness": 0.7,
-                                "conscientiousness": 0.9,
-                                "extraversion": 0.1,
-                                "agreeableness": 0.5,
-                                "neuroticism": 0.3,
-                            },
-                            "vibe": "contemplative",
-                        },
-                        "ui_hints": {"icon": "well", "color_hint": "#5b8aa3"},
-                    }
-                ],
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            agents = await list_agents(client)
-        assert len(agents) == 1
-        a = agents[0]
-        assert isinstance(a, AgentInfo)
-        assert a.agent_id == "mimir"
-        assert a.name == "Mimir"
-        assert a.description == "Keeper of the Well of Knowledge."
-        assert a.version == "0.2.0"
-        assert a.capabilities == ["knowledge_base", "semantic_search"]
-        assert a.supported_models == ["default", "heavy"]
-        assert a.persona_traits["vibe"] == "contemplative"
-        assert a.ui_hints["icon"] == "well"
-
-    @respx.mock
-    async def test_happy_minimum_shape(self) -> None:
-        """happy_minimum_shape: required-only agent → optional fields default."""
-        respx.get("https://w.example/agents").mock(
-            return_value=httpx.Response(
-                200,
-                json=[
-                    {
-                        "agent_id": "minimal",
-                        "name": "Minimal Agent",
-                        "description": "Just a sketch.",
-                    }
-                ],
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            agents = await list_agents(client)
-        a = agents[0]
-        assert a.agent_id == "minimal"
-        assert a.version is None
-        assert a.capabilities == []
-        assert a.supported_models == []
-        assert a.persona_traits == {}
-        assert a.ui_hints == {}
-
-    @respx.mock
-    async def test_happy_multi_agent(self) -> None:
-        """happy_multi_agent: 3 agents preserve order."""
-        respx.get("https://w.example/agents").mock(
-            return_value=httpx.Response(
-                200,
-                json=[
-                    {"agent_id": "a", "name": "A", "description": "x"},
-                    {"agent_id": "b", "name": "B", "description": "y"},
-                    {"agent_id": "c", "name": "C", "description": "z"},
-                ],
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            agents = await list_agents(client)
-        assert [a.agent_id for a in agents] == ["a", "b", "c"]
-
-    @respx.mock
-    async def test_happy_empty(self) -> None:
-        """happy_empty: 200 with [] returns empty list (no error)."""
-        respx.get("https://w.example/agents").mock(return_value=httpx.Response(200, json=[]))
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            agents = await list_agents(client)
-        assert agents == []
-
-    @respx.mock
-    async def test_omit_capabilities_empty_list(self) -> None:
-        """omit_capabilities_empty: explicit [] from server still defaults to []."""
-        respx.get("https://w.example/agents").mock(
-            return_value=httpx.Response(
-                200,
-                json=[
-                    {
-                        "agent_id": "a",
-                        "name": "A",
-                        "description": "x",
-                        "capabilities": [],
-                    }
-                ],
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            agents = await list_agents(client)
-        assert agents[0].capabilities == []
-
-    @respx.mock
-    async def test_500_raises_session_api_failed(self) -> None:
-        """500 → SessionApiFailed with status=500."""
-        respx.get("https://w.example/agents").mock(
-            return_value=httpx.Response(500, content=b"oops")
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(SessionApiFailed) as excinfo:
-                await list_agents(client)
-        assert excinfo.value.status == 500
-
-    @respx.mock
-    async def test_401_raises_session_api_failed(self) -> None:
-        """401 → SessionApiFailed with status=401."""
-        respx.get("https://w.example/agents").mock(
-            return_value=httpx.Response(401, content=b'{"error":"unauthorized"}')
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(SessionApiFailed) as excinfo:
-                await list_agents(client)
-        assert excinfo.value.status == 401
-
-
-class TestGetPersonaState:
-    """Worldtree #204 / v0.28.0 — GET /agents/{agent_id}/persona_state.
-
-    Bootstrap read for the persona snapshot — same shape as `affect_update`'s
-    `current` snapshot. Auth via `persona.read` scope (user-tier default).
-    """
-
-    @respx.mock
-    async def test_happy_full_snapshot(self) -> None:
-        """happy_full_snapshot [happy,tracer]: 200 → snapshot dict with pad +
-        dominant_emotion + emotions_active + baseline_pad + mood_drift.
-        """
-        snapshot = {
-            "agent_id": "mimir",
-            "pad": {"pleasure": 0.52, "arousal": 0.47, "dominance": 0.50},
-            "dominant_emotion": "curiosity",
-            "emotions_active": [
-                {"type": "curiosity", "intensity": 0.6, "decay_remaining_s": 202.7}
-            ],
-            "baseline_pad": {"pleasure": 0.50, "arousal": 0.40, "dominance": 0.50},
-            "mood_drift": {"valence_delta": 0.02, "arousal_delta": 0.07},
-            "last_updated_at": "2026-05-25T22:30:18+00:00",
-        }
-        respx.get("https://w.example/agents/mimir/persona_state").mock(
-            return_value=httpx.Response(200, json=snapshot)
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            result = await get_persona_state(client, "mimir")
-        assert result == snapshot
-
-    @respx.mock
-    async def test_persona_not_configured_404(self) -> None:
-        """persona_not_configured_404 [error]: 404 with error_code
-        persona_not_configured → PersonaNotConfigured. Agent exists but has
-        no persona surface (e.g. domari, muninn, Tier 3).
-        """
-        respx.get("https://w.example/agents/domari/persona_state").mock(
-            return_value=httpx.Response(
-                404, json={"error_code": "persona_not_configured", "message": "no persona"}
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(PersonaNotConfigured) as exc_info:
-                await get_persona_state(client, "domari")
-        assert exc_info.value.agent_id == "domari"
-
-    @respx.mock
-    async def test_agent_not_available_404(self) -> None:
-        """agent_not_available_404 [error]: 404 with error_code
-        agent_not_available → AgentNotAvailable. Distinct from
-        persona_not_configured — the agent_id itself is unknown.
-        """
-        respx.get("https://w.example/agents/bogus/persona_state").mock(
-            return_value=httpx.Response(
-                404, json={"error_code": "agent_not_available", "message": "unknown agent"}
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(AgentNotAvailable) as exc_info:
-                await get_persona_state(client, "bogus")
-        assert exc_info.value.agent_id == "bogus"
-
-    @respx.mock
-    async def test_auth_scope_denied_403(self) -> None:
-        """auth_scope_denied_403 [error]: 403 with error_code auth_scope_denied
-        → AuthScopeDenied. Key lacks `persona.read` scope.
-        """
-        respx.get("https://w.example/agents/mimir/persona_state").mock(
-            return_value=httpx.Response(
-                403,
-                json={"error_code": "auth_scope_denied", "message": "missing persona.read"},
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(AuthScopeDenied) as exc_info:
-                await get_persona_state(client, "mimir")
-        assert exc_info.value.scope == "persona.read"
-
-    @respx.mock
-    async def test_404_unknown_error_code_falls_through(self) -> None:
-        """404_unknown_error_code_falls_through [adversarial]: 404 without the
-        two known error codes → SessionApiFailed (don't swallow novel failure
-        modes as something more specific than they are).
-        """
-        respx.get("https://w.example/agents/mimir/persona_state").mock(
-            return_value=httpx.Response(404, json={"error_code": "novel_404"})
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(SessionApiFailed) as exc_info:
-                await get_persona_state(client, "mimir")
-        assert exc_info.value.status == 404
-
-    @respx.mock
-    async def test_500_unexpected_status(self) -> None:
-        """500_unexpected_status [error]: 5xx → SessionApiFailed (matches the
-        list_agents / list_sessions / create_session precedent)."""
-        respx.get("https://w.example/agents/mimir/persona_state").mock(
-            return_value=httpx.Response(500, content=b"boom")
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(SessionApiFailed) as exc_info:
-                await get_persona_state(client, "mimir")
-        assert exc_info.value.status == 500
-
-    @respx.mock
-    async def test_auth_scope_denied_detail_envelope(self) -> None:
-        """auth_scope_denied_detail_envelope [regression]: real Worldtree
-        returns `{"detail": {"error_code": "auth_scope_denied", …}}`
-        (FastAPI default), not flat `{"error_code": …}`. Smoke against
-        personal:8081 2026-05-28 surfaced this — pre-fix the response
-        fell through to SessionApiFailed(403) instead of AuthScopeDenied.
-        """
-        respx.get("https://w.example/agents/mimir/persona_state").mock(
-            return_value=httpx.Response(
-                403,
-                json={
-                    "detail": {
-                        "error_code": "auth_scope_denied",
-                        "message": "Missing required scope: persona.read",
-                    }
-                },
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(AuthScopeDenied) as exc_info:
-                await get_persona_state(client, "mimir")
-        assert exc_info.value.scope == "persona.read"
-
-    @respx.mock
-    async def test_persona_not_configured_detail_envelope(self) -> None:
-        """persona_not_configured_detail_envelope [regression]: same
-        envelope-shape unwrap on 404 + persona_not_configured.
-        """
-        respx.get("https://w.example/agents/domari/persona_state").mock(
-            return_value=httpx.Response(
-                404,
-                json={"detail": {"error_code": "persona_not_configured"}},
-            )
-        )
-        async with httpx.AsyncClient(base_url="https://w.example") as client:
-            with pytest.raises(PersonaNotConfigured) as exc_info:
-                await get_persona_state(client, "domari")
-        assert exc_info.value.agent_id == "domari"
-
-
 class TestGetMe:
     """docs/contracts/issues/2.contract.md FN get_me (slice: capabilities+me)."""