Merge remote-tracking branch 'origin/master' into worktree/acp-automation-protocol

# Conflicts:
#	.agents/notes/implemented/architecture/2026-06-14-session-persistence.md
#	.agents/notes/implemented/architecture/2026-06-20-package-hierarchy.md
#	.agents/notes/implemented/architecture/2026-07-02-tool-render-intent-union.md
#	.agents/notes/implemented/feature/2026-06-14-acp-agent-client-protocol.md
#	.agents/notes/implemented/feature/2026-06-14-acp-multi-session.md
#	.agents/notes/implemented/feature/2026-06-18-acp-terminal-and-tool-rendering.md
#	.agents/notes/implemented/feature/2026-07-19-model-facing-goal-tools.i18n.yaml
#	.agents/notes/implemented/feature/2026-07-19-model-facing-goal-tools.md
#	.agents/notes/implemented/feature/2026-07-19-model-facing-goal-tools.zh.md
#	.agents/notes/implemented/simplification/2026-07-04-trim-acp-bridge-unreachable-surface.md
#	docs/architecture.i18n.yaml
#	docs/cookbook/extension-cookbook.i18n.yaml
#	docs/cookbook/extension-cookbook.md
#	docs/cookbook/extension-cookbook.zh.md
#	docs/core-data-structures/approval.md
#	docs/core-data-structures/user-interaction.md
#	docs/event-producer-consumer.md
#	docs/persistence-catalog.md
#	docs/testing.md
#	docs/tool-catalog.md
#	examples/acp-agent/tests/fixtures/live-mode-switching-2026-07-07.session.jsonl
#	examples/acp-agent/tests/snapshots/cordis-inspect-jsdoc/stdout.expected.jsonl
#	examples/acp-agent/tests/snapshots/permission-switching/session.jsonl
#	packages/goal/tool-goal/README.md
#	packages/ui/acp/README.md
#	packages/ui/acp/acp-feature-support.md
#	packages/ui/acp/src/index.ts
#	packages/ui/acp/tests/bridge.spec.ts
#	packages/ui/acp/tests/dispose.spec.ts
#	packages/ui/acp/tests/edges.spec.ts
#	packages/ui/acp/tests/turns.spec.ts

packages/host/runtime/src/api-proxy.ts

@@ -4,7 +4,7 @@
  */
 
 import { randomUUID } from 'node:crypto'
-import { stat } from 'node:fs/promises'
+import { mkdir, stat } from 'node:fs/promises'
 import type { Context } from 'cordis'
 import type { Agent, AgentStatus } from '@deepseek-ai/dsh-agent'
 import type { ContentBlock, MessageSource } from '@deepseek-ai/dsh-llm'
@@ -407,8 +407,18 @@ export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiPro
         const sessionId = `session-${randomUUID()}` as SessionId
         // A session's cwd is its project path. When the creator does not choose
         // one, the default project is the host-level default (the host process
-        // working directory unless boot overrides it).
+        // working directory unless boot overrides it). Ensure the directory
+        // exists so Create-workspace and typed paths land on a real folder.
         const cwd = request.payload.cwd ?? defaults.cwd
+        try {
+          await mkdir(cwd, { recursive: true })
+        } catch (error: unknown) {
+          return err(request, {
+            code: 'internal',
+            message: `failed to ensure project directory "${cwd}": ${String(error)}`,
+            details: {},
+          })
+        }
         const handle = await ctx.agents.create({ sessionId, agentOptions, meta: { cwd } })
         return ok(request, { sessionId: handle.agent.id })
       },
@@ -437,7 +447,7 @@ export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiPro
         const source: MessageSource = { kind: 'user', rpcId: request.rpcId }
         try {
           if (mode === 'steer') agent.steer(content, { source })
-          else agent.send(content, { source })
+          else agent.followup(content, { source })
         } catch (error: unknown) {
           // A synchronous throw from send/steer means disposed or invalid input; surface as agent-busy with the reason attached.
           return err(request, { code: 'agent-busy', message: 'prompt rejected', details: { reason: String(error) } })

packages/host/runtime/tests/host-runtime.spec.ts

@@ -1,4 +1,4 @@
-import { mkdirSync, mkdtempSync, writeFileSync } from 'node:fs'
+import { existsSync, mkdirSync, mkdtempSync, writeFileSync } from 'node:fs'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
@@ -231,6 +231,29 @@ describe('sessions.create / list', () => {
     expect(first?.running).toBe(false)
     expect(first?.parentSessionId).toBeUndefined()
   })
+
+  it('ensures a missing project directory before minting the session', async () => {
+    const { api } = await boot()
+    const root = mkdtempSync(join(tmpdir(), 'dsh-host-create-cwd-'))
+    const cwd = join(root, 'nested', 'workspace')
+    expect(existsSync(cwd)).toBe(false)
+    const { sessionId } = expectOk(await api.sessions.create(request({ cwd })))
+    expect(existsSync(cwd)).toBe(true)
+    const { items } = expectOk(await api.sessions.list(request({})))
+    expect(items.find(item => item.sessionId === sessionId)?.cwd).toBe(cwd)
+  })
+
+  it('fails loud when the project directory cannot be created', async () => {
+    const { api } = await boot()
+    const root = mkdtempSync(join(tmpdir(), 'dsh-host-create-cwd-fail-'))
+    const blocker = join(root, 'file-not-dir')
+    writeFileSync(blocker, 'x')
+    const response = await api.sessions.create(request({ cwd: join(blocker, 'child') }))
+    expect(response.result.ok).toBe(false)
+    if (response.result.ok) throw new Error('expected mkdir failure')
+    expect(response.result.error.code).toBe('internal')
+    expect(response.result.error.message).toMatch(/failed to ensure project directory/)
+  })
 })
 
 describe('sessions.prompt / cancel', () => {
@@ -372,7 +395,7 @@ describe('sessions.prompt / cancel', () => {
     const { api, ctx } = running
     const { sessionId } = expectOk(await api.sessions.create(request({})))
     const agent = ctx.agents.get(sessionId) as Agent
-    agent.send([{ type: 'text', text: 'run forever' }])
+    agent.followup([{ type: 'text', text: 'run forever' }])
     expectOk(await api.sessions.cancel(request({ sessionId })))
 
     const missing = await api.sessions.cancel(request({ sessionId: 'session-none' as SessionId }))
@@ -391,7 +414,7 @@ describe('sessions.history', () => {
     const { sessionId } = expectOk(await first.api.sessions.create(request({})))
     const agent = first.ctx.agents.get(sessionId) as Agent
     const idle = waitForIdle(first.ctx, agent)
-    agent.send([{ type: 'text', text: 'save me' }])
+    agent.followup([{ type: 'text', text: 'save me' }])
     await idle
     const titleEvent = await appendTitle(first.ctx, agent, 'Persisted title')
     await first.dispose()
@@ -440,7 +463,7 @@ describe('sessions.history', () => {
     const agent = ctx.agents.get(sessionId) as Agent
     for (const text of ['q1', 'q2', 'q3']) {
       const idle = waitForIdle(ctx, agent)
-      agent.send([{ type: 'text', text }])
+      agent.followup([{ type: 'text', text }])
       await idle
     }
 
@@ -511,7 +534,7 @@ describe('events streams', () => {
 
     const agent = ctx.agents.get(sessionId) as Agent
     const idle = waitForIdle(ctx, agent)
-    agent.send([{ type: 'text', text: 'go' }])
+    agent.followup([{ type: 'text', text: 'go' }])
     await idle
     const live = await stream.next()
     expect((live.value as RpcRequest<MuxFrame>).payload.type).toBe('session/event')
@@ -574,7 +597,7 @@ describe('events streams', () => {
 
     const agent = ctx.agents.get(sessionId) as Agent
     const idle = waitForIdle(ctx, agent)
-    agent.send([{ type: 'text', text: 'run' }])
+    agent.followup([{ type: 'text', text: 'run' }])
     await idle
     const runningFrame = await stream.next()
     expect((runningFrame.value as RpcRequest<HostFrame>).payload).toMatchObject({ type: 'host/session-status', running: true })