Merge branch 'stack/agent-profiles-1-seam' into stack/agent-profiles-3-wire

Rewires this layer onto the standing-mount model:

- serviceForAgent roots its search at the agent's standing mount (parent
  scope key → live mount fiber) — the composition no longer lives under the
  agent's own fiber, and two agents on one preset now address ONE instance,
  which the sharing test asserts instead of distinctness.
- viewFor/historyPage take a registry view SCOPE. A live agent is that scope;
  a cold read uses the recorded preset's standing key via standingKeyFor —
  composing plugins but starting no agent, session, or turn. A header without
  a preset (a pre-roster log) renders through the DEFAULT preset's standing
  layer; an unusable preset degrades the read to generic cards, never fails
  it. This turns produced-files and chat-scroll green structurally, with the
  token counts untouched (no resume, so the projections fold stays detached).
- The detached projections baseline now includes every standing unit's key at
  its empty fold (todos: null): the standing mount registers units
  deterministically, which is what makes the client's "omitted key =
  capability absence → clear" rule safe again. seeded-history's contract test
  asserts the new shape.
- The standard preset's realm preamble no longer claims a shared label pools
  instances — provide() throws on the second registration under one realm
  symbol; labels join REALMS.

docs/cordis-catalog/services.md

@@ -68,14 +68,16 @@ async list(): Promise<AgentPreset[]>
 async resolve(id?: string): Promise<AgentPreset>
 
 /**
- * Compose one agent from a preset, installing it under that agent alone.
+ * Compose one agent from a preset: ensure the preset's standing mount, then
+ * parent the agent's scope key to it so the mount's registrations and
+ * listeners cover this agent.
  *
  * Call from the agent factory's `setup(agentCtx)`; a rejection there rolls
  * the agent creation back, so a broken preset never yields a half-composed
  * session.
  * @param agentCtx - the agent's scope context.
  * @param id - the preset id, or `undefined` for {@link defaultId}.
- * @returns the preset that was mounted, for the caller to record.
+ * @returns the preset that was composed, for the caller to record.
  * @throws when the preset is unknown or its composition is unusable.
  */
 async mount(agentCtx: Context, id?: string): Promise<AgentPreset>
@@ -96,9 +98,24 @@ async mount(agentCtx: Context, id?: string): Promise<AgentPreset>
  * @returns the agent's instance, or undefined when its preset mounts none.
  */
 serviceFor<K extends string & keyof Context>(agent: { ctx: Context }, name: K): Context[K] | undefined
+
+/**
+ * The standing scope key of one preset, for a host reader with no agent.
+ *
+ * A cold transcript read resolves tool presenters against the composition
+ * the session recorded, and the standing mount makes that possible without
+ * resuming anything: ensuring the mount composes plugins but starts no
+ * agent, no session, and no turn.
+ * @param id - the preset id, or `undefined` for {@link defaultId}.
+ * @returns the standing scope key readers pass as a registry view scope.
+ * @throws when the preset is unknown or its composition is unusable.
+ */
+async standingKeyFor(id?: string): Promise<ScopeKey>
 ```
 
-Source: [`packages/preset/agent-presets/src/index.ts:54`](../../packages/preset/agent-presets/src/index.ts)
+Types: [ScopeKey](../core-data-structures/scope.md)
+
+Source: [`packages/preset/agent-presets/src/index.ts:66`](../../packages/preset/agent-presets/src/index.ts)
 
 ## `ctx.agents` — `AgentRegistry`