feat: Add task management support and diagnostics endpoint

[aronchick]

Summary

Port changes from aronchick#66 to add task management documentation and a machine-readable diagnostics endpoint.

• Add docs/TASK_MANAGEMENT.md - comprehensive guide for Claude Code's task management tools
• Add multiclaude diagnostics command - outputs JSON with system info, capabilities, tool versions
• Add daemon startup diagnostics logging for monitoring
• Update supervisor/worker prompts with task management guidance (adapted to new concise style)

Changes

File	Description
docs/TASK_MANAGEMENT.md	New documentation for TaskCreate/Update/List/Get usage
internal/diagnostics/collector.go	New package for machine-readable diagnostics
internal/cli/cli.go	Add diagnostics command
internal/daemon/daemon.go	Log diagnostics on startup
internal/prompts/supervisor.md	Add task management section
internal/templates/agent-templates/worker.md	Add task management section

Test plan

• go build ./... compiles successfully
• multiclaude diagnostics outputs valid JSON with capabilities detection
• Task management detection works (Claude 2.x+ → true)
• Integration test with daemon startup logging

Example output

$ multiclaude diagnostics | jq '.capabilities'
{
  "task_management": true,
  "claude_installed": true,
  "tmux_installed": true,
  "git_installed": true
}

🤖 Generated with Claude Code

[aronchick]

✅ APPROVED FOR MERGE

Merge Queue Evaluation: This PR is approved and ready for upstream maintainer to merge.

Status:

• ✅ CI: All checks passing
• ✅ Scope: Matches title - adds task management docs and diagnostics (614 additions, 6 files)
• ✅ Roadmap: ✅ Supports P1 'Task history' roadmap item
• ✅ Type: Feature - adds documentation and diagnostics tooling
• ✅ Size: Moderate and focused (614 additions, 0 deletions, 6 files)
• ✅ No reviews blocking

What it adds:

• docs/TASK_MANAGEMENT.md - Guide for Claude Code's TaskCreate/Update/List/Get tools
• multiclaude diagnostics command - JSON output with system capabilities
• Task management guidance in supervisor/worker prompts
• Diagnostics logging on daemon startup

Roadmap alignment: P1 item states "Task history: Track what workers have done and their outcomes" - this adds the task management foundation and documentation.

Upstream maintainer: This PR is ready to merge whenever you're ready.

[dlorenc]

Merge Conflicts

This PR now has merge conflicts with main after recent merges. The conflicts are likely in internal/cli/cli.go since several PRs that touched that file were just merged.

Please rebase onto main to resolve the conflicts:

git fetch upstream
git rebase upstream/main
# resolve conflicts
git push --force-with-lease

Once conflicts are resolved and CI passes, this will be ready to merge.

/cc @aronchick

[dlorenc]

PR Review: feat: Add task management support and diagnostics endpoint

Issues Found

1. Bug: Incorrect signal check for process detection (High)

In internal/diagnostics/collector.go:291:

err = process.Signal(os.Signal(nil))

This should use syscall.Signal(0) to match the canonical implementation in the codebase (see internal/daemon/pid.go:72). The os.Signal(nil) approach is semantically incorrect and may cause unreliable daemon status detection.

2. Hardcoded version in daemon (Medium)

In internal/daemon/daemon.go:151:

version := "dev"

This hardcodes "dev" instead of using the actual version. Consider passing version as a parameter to NewDaemon() or using debug.ReadBuildInfo() directly.

3. Missing unit tests (Medium)

The new internal/diagnostics/ package has no test file. The existing internal/bugreport/collector_test.go shows the expected pattern. Tests should cover:

• Collect() with valid paths
• detectTaskManagementSupport() version parsing
• JSON output formatting

4. Potentially non-existent documentation URL (Low)

In docs/TASK_MANAGEMENT.md:167, the URL https://platform.claude.com/docs/en/agent-sdk/todo-tracking may not exist. Verify or remove.

What Looks Good

• Documentation quality aligns with brownian ratchet philosophy
• Proper redaction of sensitive environment variables
• Clean JSON structure with well-designed types
• Concise prompt updates matching style from #302

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🤖 Review by Claude Code