feat: auto-discover external agents during enable, rewind, and resume

[alishakawaguchi]

Summary

• Fix chicken-and-egg problem in setup: External agent discovery was gated behind the external_agents setting, which doesn't exist until after entire enable writes it. Added DiscoverAndRegisterAlways() that bypasses the settings check for interactive setup flows, so external agents appear in first-time agent selection.
• Auto-enable external_agents setting: When a user selects an external agent during setup, the external_agents setting is automatically enabled in the written config.
• Discover external agents in rewind/resume: entire rewind and entire resume now call DiscoverAndRegister() so checkpoints from external agents can be resolved.
• Add discovery timeout: 10s timeout prevents PATH scanning from blocking the CLI if the filesystem is slow.

Test plan

• Unit tests for DiscoverAndRegisterAlways (finds agents without settings)
• Unit tests for IsExternal (true for wrapped agents, false for built-ins)
• Unit test for dynamically registered agents resolving by type in ResolveAgentForRewind
• Manual: run entire enable with an entire-agent-* binary on PATH — verify it appears in agent selection
• Manual: select an external agent during enable — verify external_agents: true in settings
• Manual: create checkpoints with external agent, then entire rewind --list — verify checkpoints show

🤖 Generated with Claude Code

---

Note

^{Cursor Bugbot is generating a summary for commit 609fc3b. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

Comment @cursor review or bugbot run to trigger another review on this PR

[Copilot]

Pull request overview

This PR improves support for external (PATH-discovered) agent plugins across initial setup and session-management commands, so external-agent checkpoints and hook flows can work without manual preconfiguration.

Changes:

• Add DiscoverAndRegisterAlways() to allow external agent discovery during interactive setup even before external_agents exists in settings.
• Auto-enable external_agents in settings when an external agent is selected during interactive enable.
• Run external agent discovery in entire rewind and entire resume, and add a 10s discovery timeout to prevent long PATH scans.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
cmd/entire/cli/setup.go	Uses always-discovery in interactive setup/add flows; auto-enables external_agents; updates --agent help text.
cmd/entire/cli/rewind.go	Discovers external agents before resolving checkpoint agents.
cmd/entire/cli/resume.go	Discovers external agents before resolving checkpoint agents.
cmd/entire/cli/agent/external/discovery.go	Adds DiscoverAndRegisterAlways() and introduces a 10s discovery timeout.
cmd/entire/cli/agent/external/capabilities.go	Adds IsExternal() helper for detecting wrapped external agents.
cmd/entire/cli/agent/external/discovery_test.go	Adds unit tests for always-discovery and IsExternal().
cmd/entire/cli/strategy/rewind_test.go	Adds a unit test covering resolving dynamically registered agents by type.