feat(types): brand bash ids + stop brand erosion; extract Branded to dsh-brand

Type-only change (brands are zero-cost casts; no runtime/wire impact). Closes
the two gaps in the "brand ids that cross package boundaries" policy and fixes
the dependency direction so a capability package never pulls in an unrelated one.

- Extract the `Branded<B>` primitive into a new standalone type-only package
  `@deepseek-ai/dsh-brand` (packages/util/brand) with no harness-package deps.
  dsh-llm keeps its owned CallId but imports Branded from dsh-brand; dsh-session,
  dsh-agent, and dsh-bash all import Branded from there. dsh-bash depends on
  dsh-brand ALONE — never on dsh-llm or dsh-session (the architectural fix: a
  generic execution backend must not couple to the LLM or session vocabulary).
- Mint BashTaskId + OwnerToken in dsh-bash and thread them through BashTask.id,
  the get/ownerOf/list/readOutput/kill seam, the bash-local generation site, and
  the dsh-tool-bash validate/access surface. OwnerToken is a DISTINCT brand from
  SessionId so the seam stays decoupled; dsh-tool-bash is the single boundary
  that casts SessionId -> OwnerToken.
- Brand at the SOURCE, not via mid-pipeline casts: agent-loop's Config types
  agents[].id as AgentId and resumeSessionId as SessionId, so the brand enters
  at the config boundary and the inner create()/resume casts disappear (only the
  genuinely-new per-run session-id string is cast).
- Stop brand erosion: propagate CallId/SessionId/AgentId to the registry/store
  Map keys and public params/exports (SessionStore, AgentRegistry + factory
  options, the ACP session-id surface + ToolPresenter CallId map, the
  persistence coordinator, invariants pendingCalls, the pi-ai tool-call maps).
- Docs: document BashTaskId/OwnerToken in bash.md (type-equiv re-pasted), point
  the Branded type-equiv at dsh-brand, fix stale param types in the session/
  agent/bash READMEs, regenerate the cordis catalog + module graph.

Implements docs/rfc/proposed/architecture/2026-06-20-branded-ids.md

packages/core/agent/src/index.ts

@@ -7,7 +7,7 @@
 
 import { Context, Service } from 'cordis'
 import type { SessionId } from '@deepseek-ai/dsh-session'
-import type { Agent, AgentOptions } from './types.ts'
+import type { Agent, AgentId, AgentOptions } from './types.ts'
 
 export * from './types.ts'
 
@@ -26,9 +26,9 @@ declare module 'cordis' {
  */
 export interface CreateAgentOptions {
   /** The agent's id (the registry handle). */
-  agentId: string
+  agentId: AgentId
   /** The live session's id (NOT derived from agentId). */
-  sessionId: string
+  sessionId: SessionId
   /**
    * Session creation metadata: validated absolute `cwd` and `parentSession`
    * fork lineage. Mirrors the `cwd`/`parentSession` fields of
@@ -47,9 +47,9 @@ export interface CreateAgentOptions {
  */
 export interface ResumeAgentOptions {
   /** The agent's id (the registry handle). */
-  agentId: string
+  agentId: AgentId
   /** The persisted session id to load and resume on. */
-  resumeSessionId: string
+  resumeSessionId: SessionId
   /** Per-agent options (model, system prompt). */
   agentOptions?: AgentOptions
 }
@@ -103,7 +103,7 @@ const NO_FACTORY_MESSAGE = 'no agent factory registered (load an agent-loop plug
  * {@link setFactory}.
  */
 export class AgentRegistry extends Service {
-  private store = new Map<string, Agent>()
+  private store = new Map<AgentId, Agent>()
   private factory: AgentFactory | undefined
 
   constructor(ctx: Context) {
@@ -188,7 +188,7 @@ export class AgentRegistry extends Service {
     return () => void dispose()
   }
 
-  get(id: string): Agent | undefined {
+  get(id: AgentId): Agent | undefined {
     return this.store.get(id)
   }
 

packages/core/agent/src/types.ts

@@ -9,7 +9,8 @@
  * @module @deepseek-ai/dsh-agent/types
  */
 
-import type { Branded, ContentBlock, GenerateOptions, Message, MessageSource, StreamChunk } from '@deepseek-ai/dsh-llm'
+import type { Branded } from '@deepseek-ai/dsh-brand'
+import type { ContentBlock, GenerateOptions, Message, MessageSource, StreamChunk } from '@deepseek-ai/dsh-llm'
 
 /** Identifies one live agent in the registry. */
 export type AgentId = Branded<'AgentId'>