refactor(tasks): split the task registry into seam and local implementation

The tasks/ family now matches the capability-seam shape: @deepseek-ai/dsh-tasks
keeps the abstract TaskService (ctx.tasks contract, vocabulary types, snapshot
invariant companion) and the new @deepseek-ai/dsh-tasks-local carries the
process-local registry (LocalTaskService: in-memory store, settlement,
owner-cleanup effects, teardown, TASK_WAIT_TIMEOUT). Compositions and test
harnesses now load dsh-tasks-local; producers, TaskKindMap merges, and
dsh-tool-tasks keep importing the seam only.

Producer misconfiguration diagnostics name dsh-tasks-local because loading the
implementation is the fix. The registry behavior suite moves to tasks-local;
the seam keeps a stub-subclass registration test and the probe-based invariant
suite.

packages/cordis/tool-cordis/src/api-catalog.ts

@@ -768,38 +768,38 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
   },
   {
     key: 'tasks',
-    summary: 'The `tasks` service: the runtime-global background task registry.',
+    summary: 'Abstract background task registry.',
     methods: [
       {
-        signature: 'start(spec: TaskStart): TaskId',
+        signature: 'abstract start(spec: TaskStart): TaskId',
         jsDoc: '/**\n * Preflight access, validation, and owner cleanup before starting and\n * atomically registering work. A throwing starter leaves nothing registered;\n * after it returns, registration cannot fail. Settlement records the outcome,\n * notifies listeners, and releases waiters.\n * @param spec - task identity, owner, and synchronous starter.\n * @returns the registry-issued `<kind>-N` id.\n */',
       },
       {
-        signature: 'list(caller?: Agent): TaskSnapshot[]',
+        signature: 'abstract list(caller?: Agent): TaskSnapshot[]',
         jsDoc: '/**\n * List caller-owned and unowned tasks in registration order without exposing\n * another session\'s labels.\n * @param caller - reading agent; a non-agent caller sees only unowned tasks.\n * @returns fresh snapshots.\n */',
       },
       {
-        signature: 'get(id: TaskId, caller?: Agent): TaskSnapshot',
+        signature: 'abstract get(id: TaskId, caller?: Agent): TaskSnapshot',
         jsDoc: '/**\n * Return a non-consuming snapshot without changing its read cursor or notice\n * state. Throws for an unknown or foreign task.\n * @param id - task to look up.\n * @param caller - reading agent checked against the owner.\n * @returns a fresh snapshot.\n */',
       },
       {
-        signature: 'read(id: TaskId, caller?: Agent): TaskRead',
+        signature: 'abstract read(id: TaskId, caller?: Agent): TaskRead',
         jsDoc: '/**\n * Read the next stream delta, or the idempotent final output after settlement.\n * A terminal read marks the task reported. Throws for an unknown or foreign\n * task.\n * @param id - task to read.\n * @param caller - reading agent checked against the owner.\n * @returns output text and the post-read snapshot.\n */',
       },
       {
-        signature: 'kill(id: TaskId, caller?: Agent, reason?: string): \'requested\' | \'already-finished\'',
+        signature: 'abstract kill(id: TaskId, caller?: Agent, reason?: string): \'requested\' | \'already-finished\'',
         jsDoc: '/**\n * Request cancellation, then mark the task stopping and reported. A producer\n * throw propagates without changing task state. Throws for an unknown or\n * foreign task.\n * @param id - task to cancel.\n * @param caller - killing agent checked against the owner.\n * @param reason - logged reason forwarded to the producer.\n * @returns `requested` for live work, otherwise `already-finished`.\n */',
       },
       {
-        signature: 'async wait(id: TaskId, timeoutMs: number, caller?: Agent, signal?: AbortSignal): Promise<TaskSnapshot>',
-        jsDoc: '/**\n * Wait for settlement or timeout without cancelling the task. Caller abort\n * rejects only while the task is live; after settlement it returns the\n * terminal snapshot so a notice suppressed for this waiter is still delivered.\n * Timed-out and aborted waits detach their resolvers. Throws for invalid,\n * unknown, or foreign input.\n * @param id - task to wait for.\n * @param timeoutMs - positive finite wait bound in milliseconds.\n * @param caller - waiting agent checked against the owner.\n * @param signal - optional cancellation of the wait itself.\n * @returns snapshot at settlement or timeout.\n */',
+        signature: 'abstract wait(id: TaskId, timeoutMs: number, caller?: Agent, signal?: AbortSignal): Promise<TaskSnapshot>',
+        jsDoc: '/**\n * Wait for settlement or timeout without cancelling the task. Caller abort\n * rejects only while the task is live; after settlement the terminal\n * snapshot wins so a notice suppressed for this waiter is still delivered.\n * Throws for invalid, unknown, or foreign input.\n * @param id - task to wait for.\n * @param timeoutMs - positive finite wait bound in milliseconds.\n * @param caller - waiting agent checked against the owner.\n * @param signal - optional cancellation of the wait itself.\n * @returns snapshot at settlement or timeout.\n */',
       },
       {
-        signature: 'onTaskDone(listener: TaskDoneListener): () => void',
+        signature: 'abstract onTaskDone(listener: TaskDoneListener): () => void',
         jsDoc: '/**\n * Register an effect-scoped completion listener. Each listener is contained;\n * returned promises are observed but not awaited. No listener runs after\n * service disposal.\n * @param listener - receives each terminal snapshot and its exact owner.\n * @returns disposer that unregisters the listener.\n */',
       },
       {
-        signature: 'attachSurface(name: string): () => void',
+        signature: 'abstract attachSurface(name: string): () => void',
         jsDoc: '/**\n * Attach an effect-scoped surface that can read and stop tasks. {@link start}\n * refuses work while none is attached.\n * @param name - diagnostic label; duplicate names remain independent.\n * @returns disposer that detaches this surface.\n */',
       },
     ],