Use the project-origin contract in restored history

src/toad/agents.py

@@ -8,6 +8,13 @@ class AgentReadError(Exception):
     """Problem reading the agents."""
 
 
+class AgentNotFound(AgentReadError):
+    """The requested agent is absent from the available declarations."""
+
+    def __init__(self, identity: str) -> None:
+        super().__init__(f"Agent not found: {identity}")
+
+
 async def read_agents() -> dict[str, AgentDefinition]:
     """Read agent information from data/agents
 

src/toad/session_navigation.py

@@ -22,6 +22,7 @@
 from agent_comms.thread_identity import ThreadIncarnation
 
 from toad.core import events as core_events
+from toad.agents import AgentNotFound
 from toad.core.events import CoreEventStream
 from toad.navigation_preparation import CommsNavigationRequest, ThreadNavigationRequest
 from toad.session_entry import (
@@ -30,7 +31,7 @@
     PreviewSessionEntry,
     SessionEntry,
 )
-from toad.session_scope import AgentAttached, AgentBinding, AgentSession, SessionScope
+from toad.session_scope import AgentAttached, AgentBinding, AgentSession, ProjectSessionOrigin, SessionScope
 from toad.session_tracker import CommsViewKey, OpenTab, SessionDetails
 from toad.tab_identity import SessionTabIdentity, TabIdentity, TabTargetGone
 from toad.tab_identity.kinds import AcpTab, HistoryTab, MailboxTab, PreviewTab
@@ -158,7 +159,7 @@ def prepare():
             original=(prepared.root, prepared.thread.incarnation),
         )
 
-    async def history_entry(self, identity: HistoryTab, source: SessionScope) -> HistorySessionEntry:
+    async def history_entry(self, identity: HistoryTab, source: ProjectSessionOrigin) -> HistorySessionEntry:
         def participants():
             service = self.app.coordination_access.observation.observed().service
             if service.root != Path(identity.root):
@@ -301,11 +302,14 @@ async def launch(
         project: Checkout,
         initial_prompt: str | None = None,
     ) -> None:
-        entry = await self.launch_entry(
-            agent_identity, agent_session_id=agent_session_id,
-            session_pk=session_pk, project=project, initial_prompt=initial_prompt,
-        )
-        if entry is not None:
+        try:
+            entry = await self.launch_entry(
+                agent_identity, agent_session_id=agent_session_id,
+                session_pk=session_pk, project=project, initial_prompt=initial_prompt,
+            )
+        except AgentNotFound as error:
+            self.app.notify(str(error), title="Launch agent", severity="warning", markup=False)
+        else:
             await self.open(entry)
 
     async def launch_entry(
@@ -316,7 +320,7 @@ async def launch_entry(
         session_pk: int | None = None,
         project: Checkout,
         initial_prompt: str | None = None,
-    ) -> SessionEntry | None:
+    ) -> SessionEntry:
         from toad.agents import read_agents
         from toad.screens.main import MainScreen
 
@@ -334,7 +338,7 @@ async def launch_entry(
                 None,
             )
             if existing is not None:
-                return self.get(existing)
+                return self.entries[existing][existing]
         agent, title = None, None
         if session_pk is not None:
             saved = await database.session_get(session_pk)
@@ -344,9 +348,8 @@ async def launch_entry(
             agents = await read_agents()
             try:
                 agent = agents[agent_identity]
-            except KeyError:
-                app.notify("Agent not found", title="Launch agent", severity="warning", markup=False)
-                return
+            except KeyError as error:
+                raise AgentNotFound(agent_identity) from error
         tab = (
             AcpTab(session_pk) if session_pk is not None
             else await self.saved(agent, project, title=title or "New Session",

src/toad/tab_identity/__init__.py

@@ -1,3 +1,3 @@
 """Durable tab identities; Textual names are a projection of the wire identity."""
 
 from __future__ import annotations
@@ -12,7 +12,7 @@
 if TYPE_CHECKING:
     from toad.session_entry import SessionEntry
     from toad.session_navigation import SessionNavigation
-    from toad.session_scope import SessionScope
+    from toad.session_scope import ProjectSessionOrigin
 
 
 class TabTargetGone(Exception):
@@ -42,9 +42,9 @@
 class SessionTabIdentity(TabIdentity):
     """An agent or mailbox tab can own history tabs."""
 
-    async def history_source(self, navigation: SessionNavigation) -> SessionScope:
+    async def history_source(self, navigation: SessionNavigation) -> ProjectSessionOrigin:
         """An ACP session must establish its actual identity before routing history."""
         entry = await self.restore(navigation)
         await navigation.app.select_session(entry.mode)
         await navigation.app.workspace_sessions.require(entry.mode).wait_content_ready()
-        return navigation.app.workspace_sessions.require(entry.mode)
+        return navigation.app.workspace_sessions.require(entry.mode).origin.require()

src/toad/tab_identity/history_origin.py

@@ -13,7 +13,7 @@
 
 if TYPE_CHECKING:
     from toad.session_navigation import SessionNavigation
-    from toad.session_scope import SessionScope
+    from toad.session_scope import ProjectSessionOrigin
 
 
 class HistoryOrigin(DeclaredFamily, affix="HistoryOrigin"):
@@ -22,7 +22,7 @@ class HistoryOrigin(DeclaredFamily, affix="HistoryOrigin"):
     def mode_name(self) -> str: ...
 
     @abstractmethod
-    async def restore(self, navigation: SessionNavigation) -> SessionScope: ...
+    async def restore(self, navigation: SessionNavigation) -> ProjectSessionOrigin: ...
 
 
 @dataclass(frozen=True)
@@ -31,8 +31,8 @@ class WelcomeHistoryOrigin(HistoryOrigin):
     def mode_name(self) -> str:
         return WELCOME
 
-    async def restore(self, navigation: SessionNavigation) -> SessionScope:
-        source = await navigation.app.prepare_session(WELCOME)
+    async def restore(self, navigation: SessionNavigation) -> ProjectSessionOrigin:
+        source = (await navigation.app.prepare_session(WELCOME)).origin.require()
         await source.prepare_history_origin()
         return source
 
@@ -45,5 +45,5 @@ class SessionHistoryOrigin(HistoryOrigin):
     def mode_name(self) -> str:
         return self.identity.mode_name
 
-    async def restore(self, navigation: SessionNavigation) -> SessionScope:
+    async def restore(self, navigation: SessionNavigation) -> ProjectSessionOrigin:
         return await self.identity.history_source(navigation)

src/toad/tab_identity/kinds.py

@@ -1,3 +1,3 @@
 """Each tab kind carries the typed key and the operation that reopens it."""
 
 from dataclasses import dataclass
@@ -9,6 +9,7 @@
 from agent_comms.thread_identity import ThreadIncarnation
 
 from toad.conversation_kind import ConversationKind
+from toad.agents import AgentNotFound
 from toad.session_entry import PreviewSessionEntry
 from toad.tab_identity import SessionTabIdentity, TabIdentity, TabTargetGone
 from toad.tab_identity.history_origin import HistoryOrigin
@@ -27,15 +28,15 @@
             project = Checkout.checked(saved.meta_json.cwd.require_present().path)
         except ValueError as error:
             raise TabTargetGone(self, f"Saved ACP session {self.key}: {error}") from error
-        entry = await navigation.launch_entry(
-            saved.agent_identity,
-            agent_session_id=saved.agent_session_id,
-            session_pk=self.key,
-            project=project,
-        )
-        if entry is None:
-            raise TabTargetGone(self, f"Saved ACP agent {saved.agent_identity} is unavailable")
-        return entry
+        try:
+            return await navigation.launch_entry(
+                saved.agent_identity,
+                agent_session_id=saved.agent_session_id,
+                session_pk=self.key,
+                project=project,
+            )
+        except AgentNotFound as error:
+            raise TabTargetGone(self, str(error)) from error
 
 
 @dataclass(frozen=True)
@@ -50,7 +51,7 @@
         # Mailbox metadata already carries the original thread identity. Its
         # history needs the owner shell, not an ACP connection or painted body.
         entry = await self.restore(navigation)
-        return await navigation.app.prepare_session(entry.mode)
+        return (await navigation.app.prepare_session(entry.mode)).origin.require()
 
 
 @dataclass(frozen=True)