Extract action pin formatting helpers to reduce string concatenation

[Copilot]

Action pin resolution code had 11 instances of multi-part string concatenation creating unnecessary intermediate allocations. Centralized formatting into two helpers.

Changes

• Added formatting helpers in pkg/workflow/action_pins.go:

  • formatActionReference(repo, sha, version) → "repo@sha # version"
  • formatActionCacheKey(repo, version) → "repo@version"

• Replaced concatenation across:

  • 7 instances in action_pins.go (all action reference returns)
  • 4 instances in action_cache.go (Get/Set cache key generation)

Example

Before:

return actionRepo + "@" + latestPin.SHA + " # " + latestPin.Version
cacheKey := actionRepo + "@" + version

After:

return formatActionReference(actionRepo, latestPin.SHA, latestPin.Version)
cacheKey := formatActionCacheKey(actionRepo, version)

Tests added for both helpers covering standard cases, nested paths, and edge cases.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[plan] Extract action pin formatting helpers to reduce string concatenation</issue_title>
<issue_description>## Objective

Replace 10+ instances of multi-part string concatenation in action pin formatting with helper functions for better performance and consistency.

Context

From discussion githubnext/gh-aw#12006: Sergo analysis found repeated string concatenation patterns in action resolution code. While the codebase uses strings.Builder well (187 instances), this specific hotspot creates unnecessary intermediate allocations.

Files to Modify

• pkg/workflow/action_pins.go - 8 instances (lines 137, 159, 197, 206, 211, 246, 260, 278)
• pkg/workflow/action_cache.go - 2 instances (lines 169, 194)

Current Pattern

// Repeated 10+ times:
return actionRepo + "@" + latestPin.SHA + " # " + latestPin.Version

// In cache code:
cacheKey := repo + "@" + version

Proposed Solution

Add helper functions to centralize formatting logic:

// formatActionReference formats an action reference with repo, SHA, and version.
// Example: "actions/checkout@abc123 # v4.1.0"
func formatActionReference(repo, sha, version string) string {
    return fmt.Sprintf("%s@%s # %s", repo, sha, version)
}

// formatActionCacheKey generates a cache key for action resolution.
// Example: "actions/checkout@v4"
func formatActionCacheKey(repo, version string) string {
    return fmt.Sprintf("%s@%s", repo, version)
}

Alternative (if benchmarking shows need)

For maximum performance, use strings.Builder with pre-allocation:

func formatActionReference(repo, sha, version string) string {
    var b strings.Builder
    b.Grow(len(repo) + len(sha) + len(version) + 5)
    b.WriteString(repo)
    b.WriteString("@")
    b.WriteString(sha)
    b.WriteString(" # ")
    b.WriteString(version)
    return b.String()
}

Acceptance Criteria

• All 10+ instances replaced with helper function calls
• Helper functions defined in appropriate file (suggest action_pins.go)
• All existing tests pass with identical output
• Action pin format remains valid
• Cache key consistency maintained
• Optional: Benchmark shows performance improvement or no regression

AI generated by Plan Command for discussion #12006

Comments on the Issue (you are @copilot in this section)

• Fixes [plan] Extract action pin formatting helpers to reduce string concatenation #12180

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