Fix wtc_list MCP tool always reporting status as "up"

[samjbobb]

Summary

The wtc_list MCP tool reports status: "up" for every worktree regardless of whether its compose stack is actually running. The CLI's wtc list is correct; the MCP version isn't.

Root cause

docker compose -p <project> ps --format json exits 0 with empty output when the project doesn't exist. The MCP server's check is:

const up =
  execSafe(`docker compose -p "${project}" ps --format json`, {
    cwd: wt.path,
  }) !== null;

execSafe returns null only when the command throws — empty stdout from a non-existent project still returns a string, so up is always true.

The CLI already handles this correctly in src/commands/list.ts:

return result !== null && result.length > 2;

This PR applies the same length > 2 guard in the MCP listWorktrees.

Repro

With no worktree compose stacks running:

$ docker compose -p valencia-wt-2-mybranch ps --format json
$ echo $?
0

Empty output, exit 0 → MCP reports up, CLI correctly reports down.

After

MCP wtc_list status field now matches the CLI.

Test plan

• pnpm build passes
• pnpm test — all 33 existing tests pass
• Manual: with no compose stacks running, MCP wtc_list returns status: "down" for all worktrees, matching wtc list
• Manual: after wtc start <n>, MCP wtc_list returns status: "up" for that worktree

Summary by CodeRabbit

• Bug Fixes
  • Improved worktree status detection to be more accurate and reliable when determining operational status.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 683ae189-f963-499a-bd2e-968d927332be

📥 Commits

Reviewing files that changed from the base of the PR and between abcc90c and ff49a7b.

📒 Files selected for processing (1)

• src/mcp/server.ts

---

📝 Walkthrough

Walkthrough

The listWorktrees function now refines container status detection by validating both the presence and meaningful content of docker compose ps --format json output. The status is marked "up" only when output is non-null with length greater than 2, replacing the prior check that only validated non-nullity.

Changes

Container Status Detection

Layer / File(s)	Summary
Status Logic Refinement src/mcp/server.ts	Container status is now determined by assigning execSafe output to psOutput and validating both non-nullity and length > 2, replacing the prior non-null-only check.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~5 minutes

Poem

A rabbit checks the Docker stream,
No longer trusting null's mere gleam,
For length must pass the test of two,
Now status glows with certainty true! 🐰✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Fix wtc_list MCP tool always reporting status as "up"' directly and clearly describes the main bug being fixed in the changeset.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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