Refactor Gemini/Antigravity log parsing and unify indentation helpers

[Copilot]

This issue identified avoidable duplication across Gemini/Antigravity engine log parsing and scattered indentation utilities. This PR consolidates the shared logic into reusable helpers while preserving existing engine behavior and call-site semantics.

• Engine log parsing deduplication

  • Added parseSingleJSONResponseLogMetrics(...) in pkg/workflow/single_json_response_logs.go.
  • Switched both GeminiEngine.ParseLogMetrics and AntigravityEngine.ParseLogMetrics to delegate to the shared parser.
  • Removed duplicated per-engine JSON response parsing structs/logic from gemini_logs.go and antigravity_logs.go.

• Indentation helper consolidation

  • Added stringutil.LeadingWhitespace and stringutil.IndentLines in pkg/stringutil/stringutil.go.
  • Routed duplicated indentation logic in:
    • pkg/parser/frontmatter_hash.go (indentationOf)
    • pkg/cli/codemod_network_firewall.go (removed local indentLines)
    • pkg/cli/yaml_frontmatter_utils.go (getIndentation now delegates to shared helper)

• Focused coverage for new shared behavior

  • Added pkg/workflow/single_json_response_logs_test.go to validate equivalent Gemini/Antigravity metrics parsing.
  • Added tests for LeadingWhitespace and IndentLines in pkg/stringutil/stringutil_test.go.

// shared parser usage
func (e *GeminiEngine) ParseLogMetrics(logContent string, verbose bool) LogMetrics {
	return parseSingleJSONResponseLogMetrics(logContent, verbose, geminiLogsLog, "Gemini")
}

func (e *AntigravityEngine) ParseLogMetrics(logContent string, verbose bool) LogMetrics {
	return parseSingleJSONResponseLogMetrics(logContent, verbose, antigravityLogsLog, "Antigravity")
}

[Copilot]

Pull request overview

This PR reduces duplication by centralizing (1) Gemini/Antigravity line-delimited JSON log metrics parsing into a shared workflow helper and (2) multiple ad-hoc indentation utilities into pkg/stringutil, while adding focused unit tests to lock in the shared behaviors.

Changes:

• Added a shared parseSingleJSONResponseLogMetrics helper and routed both Gemini and Antigravity engines to use it.
• Introduced stringutil.LeadingWhitespace and stringutil.IndentLines, then updated call sites to delegate to these helpers.
• Added unit tests covering the new shared parser behavior and the new string utilities.

Show a summary per file

File	Description
pkg/workflow/single_json_response_logs.go	New shared parser for line-delimited single-JSON-response style engine logs.
pkg/workflow/single_json_response_logs_test.go	Tests that Gemini/Antigravity metrics parsing remains equivalent after refactor.
pkg/workflow/gemini_logs.go	Removes duplicated parsing logic; delegates metrics parsing to the shared helper.
pkg/workflow/antigravity_logs.go	Removes duplicated parsing logic; delegates metrics parsing to the shared helper.
pkg/stringutil/stringutil.go	Adds shared indentation helpers (LeadingWhitespace, IndentLines).
pkg/stringutil/stringutil_test.go	Adds tests validating the new indentation helpers.
pkg/parser/frontmatter_hash.go	Switches indentation calculation to use stringutil.LeadingWhitespace.
pkg/cli/yaml_frontmatter_utils.go	Replaces local indentation extraction with stringutil.LeadingWhitespace.
pkg/cli/codemod_network_firewall.go	Replaces local indentLines with stringutil.IndentLines.

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• Files reviewed: 9/9 changed files
• Comments generated: 2