Hotfix installer failure recovery and diagnostics

[hawkff]

What

• harden installer model discovery by trying both command variants:
  • cursor-agent models
  • cursor-agent --list models
• improve build resilience in installer:
  • run bun install
  • if bun run build fails with missing-module/resolve errors, retry once with bun install --force --no-cache then rebuild
• stop swallowing command failure details in installer tasks (buildPlugin, installAiSdk now return original exec errors)
• improve installer error visibility by including a concise output summary in InstallerError.Error()
• apply the same build retry fallback in shell-only install.sh

Why

Issue context: Nomadcxx#1

Some installer runs fail without actionable context, and recent reports show build failures like unresolved module errors during installation. This hotfix makes installer failure modes self-describing and adds a safe recovery path for stale/broken dependency installs.

Validation

• go test ./cmd/installer
• go build ./cmd/installer
• tmp_home=$(mktemp -d) && HOME="$tmp_home" bun run test:ci:unit && rm -rf "$tmp_home"
• bun run test:ci:integration
• bun run build

Summary by CodeRabbit

• Bug Fixes
  • Enhanced error messages with improved clarity during installation failures
  • Added automatic retry mechanism for plugin builds when dependency issues occur
  • Improved detection and handling of module resolution errors with automatic dependency reinstallation

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR enhances error handling and resilience in the installer by adding output summarization for error messages, implementing retry logic for failed plugin builds with dependency cache clearing, and improving cursor-agent model parsing with multi-variant command attempts.

Changes

Cohort / File(s)	Summary
Error Output Summarization cmd/installer/errors.go	Added summarizeRawOutput helper to trim and truncate error output to 220 characters; enhanced InstallerError.Error() to display summarized raw output in error messages.
Build Resilience & Recovery cmd/installer/tasks.go, install.sh	Introduced isMissingModuleBuildError to detect module-resolution failures; enhanced buildPlugin with automatic retry logic that clears dependency cache and reinstalls on specific errors; updated shell script to retry bun run build after forced dependency reinstall.
Model Parsing Improvements cmd/installer/tasks.go	Extracted parseCursorModelsOutput parser function; reworked fetchCursorModels to attempt multiple command variants with timeout and ANSI code stripping for robust model discovery.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 With whiskers twitched and paws so keen,
We fortify the build machine—
When troubles strike, we now retry,
Parse models three ways, aim for sky!
Clean errors shown, less noise, more cheer,
The installer's stronger, crystal clear! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 16.67% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main changes: adding failure recovery mechanisms and diagnostic improvements to the installer, which are the core objectives.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch hotfix/installer-failure-paths

---

No actionable comments were generated in the recent review. 🎉

🧹 Recent nitpick comments

cmd/installer/errors.go (1)

8-30: LGTM - minor note on unreachable code.

The function logic is sound for extracting the last meaningful line from raw output. However, lines 26-29 appear unreachable: after strings.TrimSpace(raw) on line 9, if the result is non-empty (passed the check on line 10), at least one line from strings.Split will also be non-empty after individual trimming, so the loop will always return before reaching line 26.

This doesn't affect correctness—just dead code that could be removed for clarity.

cmd/installer/tasks.go (2)

53-53: Consider hoisting ansiRegex to package level.

The regex is recompiled on every call to fetchCursorModels. Moving it to a package-level var eliminates redundant compilation.

Proposed fix

+var ansiRegex = regexp.MustCompile(`\x1b\[[0-9;]*[a-zA-Z]`)
+
 // fetchCursorModels calls cursor-agent models and parses the output
 func fetchCursorModels() (map[string]interface{}, error) {
 	variants := [][]string{
 		{"models"},
 		{"--list", "models"},
 	}

-	ansiRegex := regexp.MustCompile(`\x1b\[[0-9;]*[a-zA-Z]`)
 	var lastErr error

---

87-92: Line 91 is unreachable.

If the loop completes without returning, lastErr is guaranteed to be set (either from an exec failure or a parse failure on the last iteration). The fallback at line 91 will never execute.

Simplified return

 	if lastErr != nil {
 		return nil, lastErr
 	}
-
-	return nil, NewParseError("failed to fetch models from cursor-agent", lastClean, fmt.Errorf("all command variants failed"))
+	// This point is unreachable since lastErr is always set if loop completes
+	return nil, lastErr
 }

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