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.

scripts/gen-doc-graphs.ts

@@ -365,9 +365,10 @@ const SERVICE_ROLES: ServiceRole[] = [
     key: 'tasks',
     pkg: 'tasks',
     title: 'Background task registry',
-    mode: 'core',
+    mode: 'seam',
+    implementations: ['tasks-local'],
     consumers: ['tool-bash', 'tool-pty', 'tool-subagent', 'tool-tasks'],
-    note: 'Producers (background bash, PTY sends, and subagent delegations) register running work; tool-tasks is the model-facing control surface that reads, lists, and kills it.',
+    note: 'Producers (background bash, PTY sends, and subagent delegations) register running work; tool-tasks is the model-facing control surface that reads, lists, and kills it; tasks-local is the process-local registry.',
   },
   {
     key: 'web',

scripts/gen-tool-catalog.ts

@@ -29,7 +29,7 @@ import SubagentService from '@deepseek-ai/dsh-subagent'
 import type { SubagentProvider } from '@deepseek-ai/dsh-subagent'
 import SkillService from '@deepseek-ai/dsh-skill'
 import * as SkillLocal from '@deepseek-ai/dsh-skill-local'
-import TaskService from '@deepseek-ai/dsh-tasks'
+import LocalTaskService from '@deepseek-ai/dsh-tasks-local'
 import * as ToolAskUser from '@deepseek-ai/dsh-tool-ask-user'
 import * as ToolBash from '@deepseek-ai/dsh-tool-bash'
 import * as ToolCordis from '@deepseek-ai/dsh-tool-cordis'
@@ -355,7 +355,7 @@ const TOOL_PACKAGES: ToolPackage[] = [
     requires: ['ctx.tools', 'ctx.tasks', 'ctx.systemPrompt'],
     writes: ['tool/call', 'tool/result', 'user/message via agent.inject() for background completion notices'],
     async mount(ctx) {
-      await ctx.plugin(TaskService)
+      await ctx.plugin(LocalTaskService)
       await ctx.plugin(ToolTasks)
     },
     note:

scripts/verify-package-readme-model-experience.ts

@@ -93,6 +93,7 @@ const SENTENCE_MODEL_EXPERIENCE: Readonly<Record<string, SentenceContract>> = {
   'packages/support/llm-mock-server': { kind: 'none', reason: 'The test server substitutes provider wire behavior without invoking a real model.' },
   'packages/support/llm-replay': { kind: 'none', reason: 'The keyless adapter invokes no provider model.' },
   'packages/tasks/tasks': { kind: 'indirect', reason: 'Producer and control-surface plugins own all model rendering over the task registry.' },
+  'packages/tasks/tasks-local': { kind: 'indirect', reason: 'The registry backend delegates model rendering to producer plugins and dsh-tool-tasks.' },
   'packages/examples/acp-demo': { kind: 'indirect', reason: 'The app bundle delegates request composition to dsh-agent-spine-demo and dsh-acp.' },
   'packages/ui/app-boot': { kind: 'indirect', reason: 'Only the loaded plugin tree contributes model context.' },
   'packages/examples/jsonrpc-demo': { kind: 'indirect', reason: 'Only the externally configured plugin tree contributes model context.' },