🎯 Repository Quality Improvement Report - Monolithic Function Decomposition

[github-actions[bot]]

Analysis Date: 2026-02-19
Focus Area: Monolithic Function Decomposition
Strategy Type: Custom (first run — no history)
Custom Area: Yes — selected because gh-aw has several functions exceeding 500–850 lines that have grown organically as features were added; decomposing them reduces review friction, simplifies testing, and improves contributor onboarding.

Executive Summary

A static scan of the gh-aw codebase identified five functions each exceeding 400 lines. The largest is createMCPServer in pkg/cli/mcp_server.go at 853 lines, which registers 8 distinct MCP tools inside a single function body. Other oversized functions include the import processing pipeline (processImportsFromFrontmatterWithManifestAndSource, 671 lines), the MCP setup generator (generateMCPSetup, 661 lines), and the activation job builder (buildActivationJob, 567 lines). None of these functions are untested — the repository has an impressive 233% test-to-source LOC ratio — but their sheer size creates review fatigue and makes future changes riskier.

The repository otherwise shows strong code health: 1,060 uses of console.Format* helpers, only 19 TODO/FIXME items, and active test coverage across all major packages. This report focuses exclusively on function decomposition as the highest-leverage structural improvement.

Full Analysis Report

Focus Area: Monolithic Function Decomposition

Current State Assessment

Metrics Collected:

Metric	Value	Status
Total Go source files	1,501	✅
Test-to-source LOC ratio	233%	✅
TODO/FIXME items	19	✅
Functions > 400 lines	5	⚠️
Largest single function	853 lines (createMCPServer)	❌
Files > 1,000 lines	6	⚠️
Console formatting adoption	1,060 usages	✅

Top 5 Oversized Functions:

Rank	Function	File	Lines
1	createMCPServer	pkg/cli/mcp_server.go	853
2	processImportsFromFrontmatterWithManifestAndSource	pkg/parser/import_processor.go	671
3	generateMCPSetup	pkg/workflow/mcp_setup_generator.go	661
4	buildActivationJob	pkg/workflow/compiler_activation_jobs.go	567
5	Anonymous method in compiler_safe_outputs_config.go	pkg/workflow/compiler_safe_outputs_config.go	523

Findings

Strengths

• Excellent test coverage ratio (233%) means refactoring is safe with the existing test suite as a safety net
• The codebase already shows strong decomposition discipline in most files (the above are outliers)
• mcp_setup_generator.go has detailed package-level documentation explaining the setup phases
• compiler_safe_outputs_config.go uses a handlerConfigBuilder fluent API — good design already present

Areas for Improvement

• createMCPServer (🔴 High): 853-line function registers 8 tools inline. Each tool's handler (including schema, description, and business logic) could be a standalone register*Tool(server, ...) function. This makes reviewing a specific tool's logic much easier.
• processImportsFromFrontmatterWithManifestAndSource (🔴 High): 671-line function with clearly distinct phases — dependency resolution, cycle detection (dfsForCycle), topological sort, and content merging. Phases already have helper functions (findCyclePath, topologicalSortImports) but the main orchestrator does too much.
• generateMCPSetup (🟡 Medium): 661-line method with well-commented phases. Phase boundaries are visible but all reside in one function.
• buildActivationJob (🟡 Medium): 567 lines; already has generatePromptInActivationJob and generateCheckoutGitHubFolderForActivation as extracted helpers, showing the right instinct. More extraction is possible.

Detailed Analysis

The pattern across all five functions is the same: incremental feature additions appended to an existing function body rather than extracting new helpers. This is natural and common in fast-moving projects. The fix is equally natural: extract coherent sub-tasks into well-named helper functions.

For createMCPServer, the structure is essentially:

func createMCPServer(...) *mcp.Server {
    // ~60 lines: setup + server creation
    // ~100 lines: "status" tool
    // ~100 lines: "compile" tool
    // ~100 lines: "logs" tool
    // ~100 lines: "audit" tool
    // ~100 lines: "mcp-inspect" tool
    // ~100 lines: "add" tool
    // ~100 lines: "update" tool
    // ~100 lines: "fix" tool
}

Each tool block is already a coherent unit. Extracting them to registerStatusTool(server, execCmd) etc. reduces the main function to ~80 lines while keeping all logic intact.

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🤖 Tasks for Copilot Agent

NOTE TO PLANNER AGENT: The following 4 tasks are designed for GitHub Copilot coding agent execution. Please split these into individual work items for the agent to process one at a time, in order (Tasks 2–4 may be done in parallel; Task 1 is independent).

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Task 1: Decompose createMCPServer into per-tool registration functions

Priority: High
Estimated Effort: Medium
Focus Area: Monolithic Function Decomposition

Description:
pkg/cli/mcp_server.go contains a single createMCPServer function that is 853 lines long. It registers 8 MCP tools (status, compile, logs, audit, mcp-inspect, add, update, fix) inline. Extract each tool's registration into a dedicated helper function to reduce the main function to ~80 lines.

Acceptance Criteria:

• createMCPServer reduced to ≤ 120 lines (setup + calls to register functions)
• Each tool extracted to its own register(Name)Tool(server *mcp.Server, execCmd func(...) *exec.Cmd) function in the same file
• All existing tests in pkg/cli/mcp_server*_test.go still pass (make test-unit)
• make fmt and make lint pass cleanly
• No behavioural changes — only structural refactoring

Code Region: pkg/cli/mcp_server.go lines 403–1255

Refactor `pkg/cli/mcp_server.go` to decompose the `createMCPServer` function (lines 403–1255, ~853 lines) into per-tool helper functions.

The function registers 8 MCP tools: status, compile, logs, audit, mcp-inspect, add, update, fix. Extract each tool's `mcp.AddTool(...)` block into its own function named `register(Name)Tool(server *mcp.Server, execCmd func(ctx context.Context, args ...string) *exec.Cmd)`. The `createMCPServer` function should then call each helper in sequence and return the server.

Rules:
- Pure structural refactoring — no logic changes
- Keep all helpers in the same file (`mcp_server.go`)
- Run `make fmt` after changes
- Verify `make test-unit` passes

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Task 2: Extract phase helpers from processImportsFromFrontmatterWithManifestAndSource

Priority: High
Estimated Effort: Medium
Focus Area: Monolithic Function Decomposition

Description:
pkg/parser/import_processor.go has a 671-line function processImportsFromFrontmatterWithManifestAndSource (line 179) that orchestrates the full import pipeline: path extraction → remote resolution → cycle detection → topological sort → content loading → merging. The cycle detection and topological sort are already extracted into findCyclePath, dfsForCycle, and topologicalSortImports. The remaining orchestration phases can be extracted further.

Acceptance Criteria:

• Main function reduced to ≤ 200 lines by extracting at least 2 sub-phases into named helpers
• All existing tests in pkg/parser/ still pass (go test -v ./pkg/parser/)
• make fmt and make lint pass
• No behavioural changes

Code Region: pkg/parser/import_processor.go lines 179–849

Refactor `pkg/parser/import_processor.go` to reduce `processImportsFromFrontmatterWithManifestAndSource` (line 179, ~671 lines).

The function has distinct phases: (1) extract import paths from frontmatter, (2) resolve remote imports, (3) detect cycles, (4) topological sort, (5) load content for each import, (6) merge results. Phases 3, 4 already have helpers. Extract phases 2 and 5 (or whichever are largest) into named private functions.

Rules:
- Pure structural refactoring — no logic changes
- Run `go test -v ./pkg/parser/` to verify
- Run `make fmt` after changes

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Task 3: Document phase boundaries in generateMCPSetup

Priority: Medium
Estimated Effort: Small
Focus Area: Monolithic Function Decomposition

Description:
pkg/workflow/mcp_setup_generator.go has a 661-line generateMCPSetup method. The file already has excellent package-level documentation listing the setup phases (Docker image download, gh-aw extension install, safe-outputs config, safe-inputs config, Serena, MCP gateway, engine MCP config rendering). However, within the function body the phase boundaries are not clearly demarcated with section comments, making navigation difficult.

Extract the largest self-contained phase (safe-outputs setup or safe-inputs setup) into a helper method, and add clear phase header comments to the remaining phases.

Acceptance Criteria:

• At least one major phase (safe-outputs or safe-inputs setup) extracted into a private method
• Remaining phase boundaries marked with // Phase N: (name) section comments
• All workflow compilation tests pass (go test -v -run "TestCompile" ./pkg/workflow/)
• make fmt passes

Code Region: pkg/workflow/mcp_setup_generator.go

Improve `pkg/workflow/mcp_setup_generator.go`'s `generateMCPSetup` method (76–736, ~661 lines).

1. Extract the safe-outputs setup phase (the block starting around "Write safe-outputs config") into a private method `(c *Compiler) generateSafeOutputsSetupSteps(yaml *strings.Builder, workflowData *WorkflowData, safeOutputConfig string)`.
2. Add `// Phase N: (description)` comments at the top of each remaining phase to match the package-level documentation.

Rules:
- Pure structural improvement — no logic changes
- Run `go test -v -run "TestCompile" ./pkg/workflow/` to verify
- Run `make fmt` after changes

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Task 4: Extract sub-job builders from buildActivationJob

Priority: Medium
Estimated Effort: Medium
Focus Area: Monolithic Function Decomposition

Description:
pkg/workflow/compiler_activation_jobs.go has buildActivationJob at 567 lines (lines 443–1009). The function already delegates to generatePromptInActivationJob and generateCheckoutGitHubFolderForActivation, showing the right pattern. The remaining inline blocks (member check step generation, safe-inputs trigger step, conditions/labels setup) can each become a helper to reduce the main function to ≤ 200 lines.

Acceptance Criteria:

• buildActivationJob reduced to ≤ 250 lines
• Extracted helpers follow the existing naming convention (e.g., generate* prefix)
• All tests in pkg/workflow/ still pass (go test -v ./pkg/workflow/)
• make fmt and make lint pass
• No behavioural changes

Code Region: pkg/workflow/compiler_activation_jobs.go lines 443–1009

Refactor `buildActivationJob` in `pkg/workflow/compiler_activation_jobs.go` (lines 443–1009, ~567 lines) to reduce its size.

Following the pattern already established by `generatePromptInActivationJob` and `generateCheckoutGitHubFolderForActivation`, extract 2–3 more self-contained step-generation blocks into private `generate*` methods. Good candidates are: the member-check permission step block, the safe-inputs trigger condition block, and the label/condition builder block.

Rules:
- Pure structural refactoring — no logic changes
- Run `go test -v ./pkg/workflow/` to verify
- Run `make fmt` after changes

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📊 Historical Context

Previous Focus Areas

Date	Focus Area	Type	Custom	Key Outcomes
2026-02-19	Monolithic Function Decomposition	Custom	Yes	Identified 5 functions >400 lines; generated 4 decomposition tasks

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🎯 Recommendations

Immediate Actions (This Week)

1. Task 1 — Decompose createMCPServer — Priority: High — Biggest single win; 853 lines → ~80 lines in main function
2. Task 2 — Extract phases from import processor — Priority: High — Second-largest function; clearer phases improve contributor onboarding

Short-term Actions (This Month)

1. Task 3 — Document/extract generateMCPSetup phases — Priority: Medium
2. Task 4 — Split buildActivationJob — Priority: Medium

Long-term Actions (This Quarter)

1. Add a linter rule (e.g., gocyclo or a custom script) to flag functions exceeding 300 lines — prevents regression
2. Consider adding a make lint-complexity target to Makefile using gocognit or similar

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📈 Success Metrics

Track these metrics to measure improvement in Monolithic Function Decomposition:

• Functions > 400 lines: 5 → 0
• Largest single function: 853 lines → ≤ 200 lines
• pkg/cli/mcp_server.go main function size: 853 lines → ≤ 120 lines
• Average function size (top 10 largest): ~540 lines → ≤ 250 lines

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Next Steps

1. Review and prioritize the 4 tasks above
2. Assign Task 1 and Task 2 to Copilot coding agent via planner (they are independent)
3. Tasks 3 and 4 can be done in parallel after Tasks 1–2 are merged
4. Re-evaluate this focus area in ~30 days; add complexity linter to prevent regression

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References:

• §22184005791

AI generated by Repository Quality Improvement Agent

• expires on Feb 26, 2026, 1:42 PM UTC

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