Merge remote-tracking branch 'origin/master' into codex/skill-system

# Conflicts:
#	docs/event-producer-consumer.md
#	docs/module-graph.md
#	docs/rfc/README.md
#	packages/core/agent-core/package.json
#	packages/core/agent-core/src/index.ts
#	packages/core/agent-loop/README.md
#	packages/core/agent-loop/src/index.ts
#	packages/ui/acp-agent/src/index.ts
#	packages/ui/acp-agent/tests/acp-agent.spec.ts
#	packages/ui/stdio-agent/README.md
#	packages/ui/stdio-agent/src/index.ts
#	packages/ui/stdio-agent/tests/stdio-agent.spec.ts

packages/core/agent-loop/src/index.ts

@@ -74,7 +74,6 @@ export class AgentLoop extends Service implements AgentFactory {
     agents: z.array(z.object({
       id: z.string().required(),
       model: z.string(),
-      systemPrompt: z.string(),
       cwd: z.string(),
       resumeSessionId: z.string(),
     })).default([]),
@@ -85,6 +84,16 @@ export class AgentLoop extends Service implements AgentFactory {
     // Provide the agent-creation factory to the registry (effect-scoped: the
     // slot is cleared on dispose).
     ctx.effect(() => this.ctx.agents.setFactory(this), 'agentLoop.setFactory()')
+    // The prompt variables the shipped loop provides, registered once. The
+    // sections themselves (`harness:identity`, `deployment:persona`) belong to
+    // dsh-system-prompt — they must survive a swapped loop plugin — but
+    // `{{model}}`/`{{cwd}}` are runtime facts of the agents THIS loop drives:
+    // it assembles with `{ agent }` each step (loop.ts), and the variables
+    // project the agent's configured model and its session workspace from that
+    // context. A provider returns undefined when the fact is absent
+    // (renderPrompt then rejects a persona that claims it — fail loud).
+    ctx.systemPrompt.variable('model', context => context.agent?.options.model)
+    ctx.systemPrompt.variable('cwd', context => context.agent?.session.header.cwd)
     for (const { id, cwd, resumeSessionId, ...options } of config.agents) {
       if (resumeSessionId !== undefined && resumeSessionId !== '') {
         // Resume a prior session instead of starting fresh. resume() needs