review: the persona becomes the system-prompt plugin's deployment config

Review round 2 (tianyicui inline comments):

- dsh-system-prompt itself registers the harness:identity (-100) and
  deployment:persona (0) sections — they must survive a swapped loop
  plugin, so they leave dsh-agent-loop; the persona text is the plugin's
  own validated 'persona' config. The model/cwd variables STAY on the
  loop: runtime facts of the agents it drives.
- AgentOptions.systemPrompt is deleted with all its forwarding plumbing:
  the app configs' systemPrompt keys become 'persona' routed through
  dsh-agent-core (schema = z.intersect of the owners'), the ACP bridge
  and tool-subagent stop carrying persona configuration, and subagent
  children now render the deployment persona like every other agent.
- Example personas drop transport/interface trivia (ACP, CLI) — facts
  irrelevant to the model.
- Root CONTEXT.md removed (not idiomatic); its persona definition was
  wrong under the new ownership anyway.
- Docs, READMEs, the prompt-variables RFC, and generated catalogs
  updated; new loop test pins the assemble-waterfall escape valve
  (an emptied assembly sends NO system field).

examples/coding-agent/tests/coding-task.e2e.ts

@@ -53,11 +53,8 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('coding task: fix a failing test
     const before = spawnSync('node', ['add.test.js'], { cwd: workdir })
     expect(before.status).not.toBe(0)
 
-    ctx = await codingHarness(workdir)
-    const agent = ctx.agentLoop.create(AgentId('e2e-task'), {
-      model: 'deepseek-v4-flash',
-      systemPrompt: SYSTEM_PROMPT,
-    })
+    ctx = await codingHarness(workdir, { persona: SYSTEM_PROMPT })
+    const agent = ctx.agentLoop.create(AgentId('e2e-task'), { model: 'deepseek-v4-flash' })
 
     agent.send([{
       type: 'text',

examples/coding-agent/tests/compaction.e2e.ts

@@ -53,6 +53,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('compaction: a long session compa
     // budget even though those blocks are stripped before the checkpoint is
     // stored.
     ctx = await codingHarness(workdir, {
+      persona: SYSTEM_PROMPT,
       compact: {
         contextWindow: 2400,
         thresholdRatio: 0.5,
@@ -63,10 +64,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('compaction: a long session compa
       },
       persistenceRoot: './.sessions',
     })
-    const agent = ctx.agentLoop.create(AgentId('e2e-compaction'), {
-      model: 'deepseek-v4-flash',
-      systemPrompt: SYSTEM_PROMPT,
-    })
+    const agent = ctx.agentLoop.create(AgentId('e2e-compaction'), { model: 'deepseek-v4-flash' })
 
     agent.send([{
       type: 'text',

examples/coding-agent/tests/full-loop.e2e.ts

@@ -20,11 +20,8 @@ afterEach(async () => {
 
 describe.skipIf(!process.env.DEEPSEEK_API_KEY)('full loop: real model + real bash tool', () => {
   it('runs a bash command on request and reports its output', async () => {
-    ctx = await codingHarness(process.cwd())
-    const agent = ctx.agentLoop.create(AgentId('e2e-loop'), {
-      model: 'deepseek-v4-flash',
-      systemPrompt: SYSTEM_PROMPT,
-    })
+    ctx = await codingHarness(process.cwd(), { persona: SYSTEM_PROMPT })
+    const agent = ctx.agentLoop.create(AgentId('e2e-loop'), { model: 'deepseek-v4-flash' })
 
     agent.send([{ type: 'text', text: 'Run `echo e2e-ok` with the bash tool and tell me its exact output.' }])
     await waitForIdle(ctx, agent)

examples/coding-agent/tests/harness.ts

@@ -33,6 +33,11 @@ export const TODO_SYSTEM_PROMPT = 'You are a coding agent. For multi-step work,
 
 /** Options for {@link codingHarness}. */
 export interface CodingHarnessOptions {
+  /**
+   * Deployment persona for the tree (the system-prompt plugin's `persona`
+   * config — per-context, not per-agent). Omitted ⇒ no persona section.
+   */
+  persona?: string
   /** Durable JSONL persistence root (the resume suite needs it; others stay file-free). */
   persistenceRoot?: string
   /**
@@ -47,7 +52,7 @@ export async function codingHarness(workdir: string, options: CodingHarnessOptio
   const ctx = new Context()
   await ctx.plugin(LlmService)
   await ctx.plugin(SessionStore)
-  await ctx.plugin(SystemPrompt)
+  await ctx.plugin(SystemPrompt, { persona: options.persona ?? '' })
   await ctx.plugin(ToolRegistry)
   await ctx.plugin(AgentRegistry)
   await ctx.plugin(AgentLoop, { agents: [] })

examples/coding-agent/tests/resume.e2e.ts

@@ -38,11 +38,11 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('resume: continue a persisted ses
     // Run 1: a fresh agent on a KNOWN session id learns a secret, then we
     // dispose the whole context (simulating process exit) so only the JSONL
     // log on disk survives.
-    ctx = await codingHarness(process.cwd(), { persistenceRoot: root })
+    ctx = await codingHarness(process.cwd(), { persona: SYSTEM_PROMPT, persistenceRoot: root })
     const first = ctx.agents.create({
       agentId: AgentId('resume-1'),
       sessionId: SESSION_ID,
-      agentOptions: { model: 'deepseek-v4-flash', systemPrompt: SYSTEM_PROMPT },
+      agentOptions: { model: 'deepseek-v4-flash' },
     }).agent as ReactLoopAgent
     first.send([{ type: 'text', text: `Remember this code for later: ${SECRET}. Just acknowledge it.` }])
     await waitForIdle(ctx, first)
@@ -52,11 +52,11 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('resume: continue a persisted ses
     // Run 2: a brand-new context over the SAME root resumes the persisted
     // session. The loaded event log seeds the live session, so the model sees
     // run 1's exchange as conversation history.
-    ctx = await codingHarness(process.cwd(), { persistenceRoot: root })
+    ctx = await codingHarness(process.cwd(), { persona: SYSTEM_PROMPT, persistenceRoot: root })
     const resumed = (await ctx.agents.resume({
       agentId: AgentId('resume-2'),
       resumeSessionId: SESSION_ID,
-      agentOptions: { model: 'deepseek-v4-flash', systemPrompt: SYSTEM_PROMPT },
+      agentOptions: { model: 'deepseek-v4-flash' },
     })).agent as ReactLoopAgent
     expect(resumed.session.id).toBe(SESSION_ID)
     // The prior user turn is in the rehydrated log before the model is asked.

examples/coding-agent/tests/todo-write.e2e.ts

@@ -18,11 +18,8 @@ afterEach(async () => {
 
 describe.skipIf(!process.env.DEEPSEEK_API_KEY)('todo_write: real model records a plan', () => {
   it('appends a todo/write event with the model-produced task list', async () => {
-    ctx = await codingHarness(process.cwd())
-    const agent = ctx.agentLoop.create(AgentId('e2e-todo'), {
-      model: 'deepseek-v4-flash',
-      systemPrompt: TODO_SYSTEM_PROMPT,
-    })
+    ctx = await codingHarness(process.cwd(), { persona: TODO_SYSTEM_PROMPT })
+    const agent = ctx.agentLoop.create(AgentId('e2e-todo'), { model: 'deepseek-v4-flash' })
 
     agent.send([{ type: 'text', text:
       'Use the todo_write tool to record a plan of exactly two steps: first '