diff --git a/apps/server/agent/manager.ts b/apps/server/agent/manager.ts
index 12e6f8d..ac2bf70 100644
--- a/apps/server/agent/manager.ts
+++ b/apps/server/agent/manager.ts
@@ -277,7 +277,7 @@ export class MultiProviderAgentManager implements AgentManager {
     const agentId = agent.id;
 
     // 3a. Append inter-agent communication instructions with actual agent ID
-    prompt = prompt + buildInterAgentCommunication(agentId);
+    prompt = prompt + buildInterAgentCommunication(agentId, mode);
 
     // 3b. Write input files (after agent creation so we can include agentId/agentName)
     if (options.inputContext) {
@@ -487,6 +487,117 @@ export class MultiProviderAgentManager implements AgentManager {
     return true;
   }
 
+  /**
+   * Resume an idle agent to answer an inter-agent conversation.
+   * Returns false if the agent can't be resumed (no session, provider doesn't support resume, etc.).
+   */
+  private conversationResumeLocks = new Set<string>();
+
+  async resumeForConversation(
+    agentId: string,
+    conversationId: string,
+    question: string,
+    fromAgentId: string,
+  ): Promise<boolean> {
+    // Concurrency guard — prevent double-resume race
+    if (this.conversationResumeLocks.has(agentId)) {
+      log.info({ agentId, conversationId }, 'conversation resume already in progress, skipping');
+      return false;
+    }
+
+    const agent = await this.repository.findById(agentId);
+    if (!agent) return false;
+    if (agent.status !== 'idle') {
+      log.debug({ agentId, status: agent.status }, 'agent not idle, skipping conversation resume');
+      return false;
+    }
+    if (!agent.sessionId) {
+      log.debug({ agentId }, 'no session ID, cannot resume for conversation');
+      return false;
+    }
+
+    const provider = getProvider(agent.provider);
+    if (!provider || provider.resumeStyle === 'none') {
+      log.debug({ agentId, provider: agent.provider }, 'provider does not support resume');
+      return false;
+    }
+
+    const agentCwd = this.processManager.getAgentWorkdir(agent.worktreeId);
+    if (!existsSync(agentCwd)) {
+      log.debug({ agentId, agentCwd }, 'worktree no longer exists, cannot resume');
+      return false;
+    }
+
+    this.conversationResumeLocks.add(agentId);
+    try {
+      const conversationPrompt =
+        `Another agent (ID: ${fromAgentId}) asked you a question via inter-agent communication.\n\n` +
+        `**Conversation ID**: ${conversationId}\n` +
+        `**Question**: ${question}\n\n` +
+        `Please answer this question using:\n` +
+        `  cw answer "<your answer>" --conversation-id ${conversationId}\n\n` +
+        `After answering, check for any other pending conversations:\n` +
+        `  cw listen --agent-id ${agentId}\n\n` +
+        `Answer any additional pending conversations the same way, then complete your session.`;
+
+      // Clear previous signal.json
+      const signalPath = join(agentCwd, '.cw/output/signal.json');
+      try {
+        await unlink(signalPath);
+      } catch {
+        // File might not exist
+      }
+
+      await this.repository.update(agentId, { status: 'running', pendingQuestions: null, result: null });
+
+      const { command, args, env: providerEnv } = this.processManager.buildResumeCommand(provider, agent.sessionId, conversationPrompt);
+      const { processEnv } = await this.credentialHandler.prepareProcessEnv(providerEnv, provider, agent.accountId);
+
+      // Stop previous tailer/poll
+      const prevActive = this.activeAgents.get(agentId);
+      prevActive?.cancelPoll?.();
+      if (prevActive?.tailer) {
+        await prevActive.tailer.stop();
+      }
+
+      let sessionNumber = 1;
+      if (this.logChunkRepository) {
+        sessionNumber = (await this.logChunkRepository.getSessionCount(agentId)) + 1;
+      }
+
+      const { pid, outputFilePath, tailer } = this.processManager.spawnDetached(
+        agentId, agent.name, command, args, agentCwd, processEnv, provider.name, conversationPrompt,
+        (event) => this.outputHandler.handleStreamEvent(agentId, event, this.activeAgents.get(agentId)),
+        this.createLogChunkCallback(agentId, agent.name, sessionNumber),
+      );
+
+      await this.repository.update(agentId, { pid, outputFilePath });
+      const activeEntry: ActiveAgent = { agentId, pid, tailer, outputFilePath };
+      this.activeAgents.set(agentId, activeEntry);
+
+      if (this.eventBus) {
+        const event: AgentResumedEvent = {
+          type: 'agent:resumed',
+          timestamp: new Date(),
+          payload: { agentId, name: agent.name, taskId: agent.taskId ?? '', sessionId: agent.sessionId },
+        };
+        this.eventBus.emit(event);
+      }
+
+      const { cancel } = this.processManager.pollForCompletion(
+        agentId, pid,
+        () => this.handleDetachedAgentCompletion(agentId),
+        () => this.activeAgents.get(agentId)?.tailer,
+      );
+      activeEntry.cancelPoll = cancel;
+
+      log.info({ agentId, conversationId, pid }, 'resumed idle agent for conversation');
+      return true;
+    } finally {
+      this.conversationResumeLocks.delete(agentId);
+    }
+  }
+
   /**
    * Sync credentials from agent's config dir back to DB after completion.
    * The subprocess may have refreshed tokens mid-session; this ensures
diff --git a/apps/server/agent/prompts/shared.ts b/apps/server/agent/prompts/shared.ts
index 71ad7e3..a23896f 100644
--- a/apps/server/agent/prompts/shared.ts
+++ b/apps/server/agent/prompts/shared.ts
@@ -119,25 +119,95 @@ Update \`.cw/output/progress.md\` after each commit:
 Survives context compaction — read this first if your context is refreshed.
 </progress_tracking>`;
 
-export function buildInterAgentCommunication(agentId: string): string {
+const PLANNING_MODES = new Set(['plan', 'refine']);
+
+export function buildInterAgentCommunication(agentId: string, mode: string = 'execute'): string {
+  if (PLANNING_MODES.has(mode)) {
+    return `
+<inter_agent_communication>
+Your agent ID: **${agentId}**
+
+You are in a planning mode (\`${mode}\`). You define high-level structure, not implementation details. Real-time coordination is almost never needed.
+
+If you are truly blocked on information only another running agent has:
+\`\`\`
+cw ask "<question>" --from ${agentId} --agent-id <TARGET_AGENT_ID>
+\`\`\`
+This blocks until the target answers. Use it as a last resort — not for approach validation.
+</inter_agent_communication>`;
+  }
+
   return `
 <inter_agent_communication>
 Your agent ID: **${agentId}**
 
-**CLI Commands**
+## Commands
 
-- \`cw listen --agent-id ${agentId}\` — Waits for incoming question. Prints JSON (\`{ conversationId, fromAgentId, question, phaseId, taskId }\`) and exits.
-- \`cw ask "<question>" --from ${agentId} --agent-id <TARGET>\` — Blocks until answered. Target with one of: \`--agent-id <id>\`, \`--task-id <id>\`, \`--phase-id <id>\`.
-- \`cw answer "<answer>" --conversation-id <ID>\` — Answer a pending question.
+| Command | Behavior |
+|---------|----------|
+| \`cw listen --agent-id ${agentId}\` | Blocks via SSE until one question arrives. Prints JSON and exits. |
+| \`cw ask "<question>" --from ${agentId} --agent-id <TARGET>\` | Creates a conversation and blocks until the target answers. Prints the answer to stdout. |
+| \`cw answer "<answer>" --conversation-id <ID>\` | Answers a pending question. Prints confirmation JSON. |
 
-**Usage Pattern**
+## Listener Lifecycle
 
-Run \`cw listen > "$file" &\` at session start. Check periodically. On question: answer, restart listener. Before signal.json: kill listener, clean up.
+Set up a background listener so you can answer questions from other agents while working.
 
-**When to Communicate**
-- Need interface/schema/API contract info from another agent
-- About to modify a shared resource
-- Have a dependency on another agent's work
-- Don't ask questions you can answer by reading the codebase
+\`\`\`bash
+# 1. Start listener, redirect to temp file
+CW_LISTEN_FILE=$(mktemp)
+cw listen --agent-id ${agentId} > "$CW_LISTEN_FILE" &
+CW_LISTEN_PID=$!
+
+# 2. Between work steps, check for incoming questions
+if [ -s "$CW_LISTEN_FILE" ]; then
+  # 3. Parse the JSON, answer, clear, restart
+  CONV_ID=$(cat "$CW_LISTEN_FILE" | jq -r '.conversationId')
+  QUESTION=$(cat "$CW_LISTEN_FILE" | jq -r '.question')
+  # Read code / think / answer with specifics
+  cw answer "<your answer>" --conversation-id "$CONV_ID"
+  > "$CW_LISTEN_FILE"
+  cw listen --agent-id ${agentId} > "$CW_LISTEN_FILE" &
+  CW_LISTEN_PID=$!
+fi
+
+# 4. Before writing signal.json — kill listener and clean up
+kill $CW_LISTEN_PID 2>/dev/null
+rm -f "$CW_LISTEN_FILE"
+\`\`\`
+
+## Targeting
+
+- \`--agent-id <id>\` — You know exactly which agent to ask (e.g., from manifest or a previous conversation).
+- \`--task-id <id>\` — Ask whichever agent is currently running that task.
+- \`--phase-id <id>\` — Ask whichever agent is working in that phase. Use when you need something from an adjacent phase but don't know the agent ID.
+
+## When to Ask
+
+- You need an **uncommitted interface contract** — an export path, method signature, type definition, or schema that another agent is actively creating and hasn't pushed yet.
+- You are about to **modify a shared file** that another agent may also be editing, and you need to coordinate who changes what.
+
+## When NOT to Ask
+
+- The answer is in the **codebase** — search first (\`grep\`, \`find\`, read the code).
+- The answer is in your **input files or context files** — read them again before asking.
+- You are **not actually blocked** — if you can make a reasonable decision and move on, do that.
+- You want to **confirm your approach** — that's not what inter-agent communication is for. Make the call.
+
+<example label="bad">
+"How should I structure the API response for the users endpoint?"
+This is a design decision you should make based on existing codebase patterns.
+</example>
+
+<example label="good">
+"What will the export path and method signature be for createUser() in packages/shared/src/api/users.ts? I need to import it."
+This asks for a specific uncommitted artifact another agent is building.
+</example>
+
+## Answering Questions
+
+When you receive a question, be **specific**. Include the actual code snippet, file path, type signature, or schema. Vague answers force a follow-up round-trip.
+
+Check for incoming questions between commits — not after every line of code.
 </inter_agent_communication>`;
 }
diff --git a/docs/agent.md b/docs/agent.md
index 57fe6b6..00d46a2 100644
--- a/docs/agent.md
+++ b/docs/agent.md
@@ -143,12 +143,18 @@ Agent output is persisted to `agent_log_chunks` table and drives all live stream
 Agents can communicate with each other via the `conversations` table, coordinated through CLI commands.
 
 ### Prompt Integration
-`buildInterAgentCommunication(agentId)` function in `prompts/shared.ts` generates per-agent communication instructions. Called in `manager.ts` after agent record creation — the actual agent ID is injected directly into the prompt (no manifest.json indirection). Appended to the prompt regardless of mode. Instructions include:
-1. Set up a background listener via temp-file redirect: `cw listen > $CW_LISTEN_FILE &`
-2. Periodically check the temp file for incoming questions between work steps
-3. Answer via `cw answer`, clear the file, restart the listener
-4. Ask questions to peers via `cw ask --from <agentId> --agent-id|--task-id|--phase-id`
-5. Kill the listener and clean up the temp file before writing `signal.json`
+`buildInterAgentCommunication(agentId, mode)` function in `prompts/shared.ts` generates per-agent communication instructions. Called in `manager.ts` after agent record creation — the actual agent ID is injected directly into the prompt (no manifest.json indirection).
+
+**Mode-aware branching:**
+
+- **Planning modes** (`plan`, `refine`): Minimal block — just the agent ID and `cw ask` syntax for emergencies. These agents define high-level structure, not implementation details, so real-time coordination is almost never needed.
+- **Execution + coordination modes** (`execute`, `detail`, `discuss`, `verify`, `merge`, `review`): Full protocol including:
+  1. Commands table with accurate CLI behavior descriptions
+  2. Numbered shell recipe for background listener lifecycle (start → check → answer → restart → cleanup)
+  3. Targeting guidance (`--agent-id` vs `--task-id` vs `--phase-id`)
+  4. Decision criteria: when to ask (uncommitted interfaces, shared file conflicts) and when NOT to ask (answer in codebase, answer in input files, not blocked, confirming approach)
+  5. Good/bad examples using `<example label>` pattern
+  6. Answering guidelines (be specific — include code snippets, file paths, type signatures)
 
 ### Agent Identity
 `manifest.json` includes `agentId` and `agentName` fields. The manager passes these from the DB record after agent creation. The agent ID is also injected directly into the prompt's communication instructions.