fix: reuse runtime processes across project sessions

Multiple projects could spawn duplicate heavyweight runtimes, while settings
changes and remote reconnection could cancel or strand native conversations.
Share compatible local OpenCode and DeepSeek Harness process owners and
Agent-owned ACP connections, retaining workspace routing, per-session modes,
model attribution, question ownership, targeted cancellation and idle cleanup.

Restore remote pending questions and terminal task projections across reconnect
and desktop restart, and preserve accepted ordinary requests during settings
replacement while cancelling expert-team parents with their replaced scheduler.
Extend regression coverage and Agent type checks. Record measured resource and
real-model validation results, including failures and limitations.

Also include the conversation media-generation design drafts (not an implemented
feature), documentation entry links and dedicated Linux test-directory guidance.
Desktop and Agent changes must be delivered together for shared process results.

Validation: typecheck and lint passed; staged content and documentation links
checked. Prior full regression and live-model evidence are recorded in progress
notes; no new full test suite or model calls were run for this commit.

Release note: 多项目会话现在复用兼容的 OpenCode 和 DeepSeek Harness 进程，减少重复启动并保持工作区、工具和取消隔离。修复远端问答在断线、重启及配置更新后的恢复与状态同步问题，Desktop 与 Agent 需配套更新。

src/agent-daemon/direct-linux-stdio-process-owner.ts

@@ -108,6 +108,7 @@ export type DirectLinuxStdioProcessOwnerOptions = {
       bridgeDirectory: string
       socketPath: string
       policy: ModelBridgePolicy
+      sharedSessions?: boolean
     }
   }
   identity: { launchId: string; processId: string }
@@ -115,6 +116,7 @@ export type DirectLinuxStdioProcessOwnerOptions = {
   registry: RuntimeOwnerRegistry
   deadlineAt: string
   maximumInputBytes: number
+  sharedSessions?: boolean
   signal?: AbortSignal
   platform?: NodeJS.Platform
   spawn?: DirectLinuxStdioSpawn
@@ -151,6 +153,7 @@ export class DirectLinuxStdioProcessOwner {
   readonly processIdentity: LinuxRuntimeProcessIdentity
 
   readonly #child: DirectLinuxStdioChild
+  readonly #sharedSessions: boolean
   readonly #registry: RuntimeOwnerRegistry
   readonly #now: () => number
   readonly #readIdentity: typeof readLinuxRuntimeProcessIdentity
@@ -194,6 +197,7 @@ export class DirectLinuxStdioProcessOwner {
     listPidNamespaceMembers: typeof listLinuxPidNamespaceMembers
     sendSignal: typeof process.kill
     maximumInputBytes: number
+    sharedSessions?: boolean
     maximumPendingStdinBytes: number
     maximumStdinWriteBytes: number
     maximumOutputBytes: number
@@ -208,6 +212,7 @@ export class DirectLinuxStdioProcessOwner {
     this.ownerId = input.ownerId
     this.processIdentity = Object.freeze({ ...input.processIdentity })
     this.#child = input.child
+    this.#sharedSessions = input.sharedSessions === true
     this.#registry = input.registry
     this.#now = input.now
     this.#readIdentity = input.readProcessIdentity
@@ -222,7 +227,7 @@ export class DirectLinuxStdioProcessOwner {
       input.maximumPromptRuntimeMilliseconds
     this.#maximumOutputQueueChunks = input.maximumOutputQueueChunks
     this.#maximumListeners = input.maximumListeners
-    this.#scheduleDeadline(input.deadlineAt)
+    if (!this.#sharedSessions) this.#scheduleDeadline(input.deadlineAt)
     input.child.stdout.on('data', (chunk: Buffer | Uint8Array) => {
       this.#acceptOutput(chunk)
     })
@@ -245,13 +250,13 @@ export class DirectLinuxStdioProcessOwner {
     }
     if (
       payload.byteLength > this.#maximumStdinWriteBytes ||
-      this.#inputBytes + payload.byteLength > this.#maximumInputBytes ||
+      (!this.#sharedSessions && this.#inputBytes + payload.byteLength > this.#maximumInputBytes) ||
       this.#pendingInputBytes + payload.byteLength > this.#maximumPendingStdinBytes
     ) {
       throw capacityError('Runtime stdin quota reached')
     }
     const copy = Buffer.from(payload)
-    this.#inputBytes += copy.byteLength
+    if (!this.#sharedSessions) this.#inputBytes += copy.byteLength
     this.#pendingInputBytes += copy.byteLength
     const write = this.#writeTail.then(async () => {
       if (this.#closed || this.#stdinClosed || !this.#promptActive) {
@@ -268,6 +273,7 @@ export class DirectLinuxStdioProcessOwner {
   }
 
   beginPrompt(input: { deadlineAt: string; maximumInputBytes: number }): void {
+    if (this.#sharedSessions && !this.#closed && !this.#stdinClosed) return
     if (this.#closed || this.#stdinClosed || this.#promptActive) {
       throw new DirectLinuxStdioProcessOwnerError(
         this.#promptActive ? 'A Runtime prompt is already active' : 'Runtime process is closed',
@@ -293,6 +299,7 @@ export class DirectLinuxStdioProcessOwner {
   }
 
   async completePrompt(): Promise<void> {
+    if (this.#sharedSessions) return
     if (!this.#promptActive) return
     await this.#writeTail
     this.#promptActive = false
@@ -655,6 +662,7 @@ export async function launchDirectLinuxStdioProcessOwner(
         options.listPidNamespaceMembers ?? listLinuxPidNamespaceMembers,
       sendSignal: options.sendSignal ?? process.kill,
       maximumInputBytes,
+      sharedSessions: options.sharedSessions,
       maximumPendingStdinBytes,
       maximumStdinWriteBytes,
       maximumOutputBytes: manifest.limits.maximumPromptOutputBytes,
@@ -975,7 +983,7 @@ function defaultSpawn(
   args: readonly string[],
   options: Parameters<DirectLinuxStdioSpawn>[2]
 ): DirectLinuxStdioChild {
-  return nodeSpawn(executable, [...args], options)
+  return nodeSpawn(executable, [...args], { ...options, stdio: [...options.stdio] })
 }
 
 async function waitForSpawn(