Summary

The plan text was accidentally dropped from the ExitPlanMode content array during the switch to built-in Claude Code tools (#316, commit be618f5). This meant ACP clients could not display the plan when asking the user for approval — they only saw the title "Ready to code?" with no plan body.

We noticed this in the Fabriqa app where our plan approval UI was rendering an empty card.

What changed

Restored the original input.plan → content mapping in toolInfoFromToolUse() so the plan markdown is included in the tool_call and request_permission events.

Before (broken):

case "ExitPlanMode": {
  return {
    title: "Ready to code?",
    kind: "switch_mode",
    content: [],
  };
}

After (fixed):

case "ExitPlanMode": {
  const planInput = toolUse.input as { plan?: string };
  return {
    title: "Ready to code?",
    kind: "switch_mode",
    content:
      planInput?.plan
        ? [{ type: "content" as const, content: { type: "text" as const, text: planInput.plan } }]
        : [],
  };
}

Where does input.plan come from?

The Claude Agent SDK passes tool inputs to the canUseTool callback as Record<string, unknown> (see Options.canUseTool in @anthropic-ai/claude-agent-sdk/sdk.d.ts). When Claude calls ExitPlanMode, the model includes the plan text in the input.

The formal ExitPlanModeInput type (in @anthropic-ai/claude-agent-sdk/sdk-tools.d.ts) only declares allowedPrompts, but it has a [k: string]: unknown index signature that allows additional properties. The model consistently sends plan (string) and planFilePath (string). SDK v0.2.76 explicitly added planFilePath to the tool input for hooks and SDK consumers, confirming these fields are intentional.

The original implementation (commit 0289dd9, "Support plan mode and all other permission modes" #40) relied on input.plan and worked correctly until the refactor in #316 dropped it.

SDK history confirms input.plan is reliable

The Claude Agent SDK itself had a regression where ExitPlanMode input was empty (anthropics/claude-code#12288):

The SDK team treated the empty input as a critical bug and fixed it promptly. The current SDK (0.2.76) reliably sends input.plan, so this adapter fix is safe to depend on.

Test plan

• Added test: plan text is included in content when input.plan is provided
• Added test: content is empty when input.plan is not provided
• All existing tests pass

Fixes #450