refactor: hub-aware decompose grouping to prevent mega-clusters

[chubes4]

Summary

• Fix: The refactor decompose algorithm used undirected union-find for call graph clustering, which collapsed everything reachable from a high-fan-out orchestrator function into a single mega-group
• Change: Identify "hub" functions (≥4 callees) and exclude their edges from clustering, producing focused sub-groups instead of mega-clusters
• Change: Add dominant prefix detection for semantic cluster naming (e.g., resolve_* functions → resolve.rs) instead of naming after the most-called function

Before vs After

contract_testgen.rs (2,998 lines)

Before (3 groups, one mega-group of 15):

infer_hint_for_param.rs — 15 functions (including the main API!)
make_test_async.rs      — 2 functions
types.rs                — 3 structs

After (8 focused groups):

build.rs              — build_param_inputs, build_variables
condition_contains.rs — condition_contains_param_method, condition_contains_negated_method
default_call_arg.rs   — default_call_arg, infer_setup_from_condition, resolve_constructor
generate_test.rs      — generate_test_plan, generate_test_plan_with_types
helpers.rs            — derive_template_key, slugify, infer_hint_for_param, extract_method_string_arg
like.rs               — is_path_like, is_numeric_like
make_test_async.rs    — make_test_async, render_test_plan
types.rs              — SetupOverride, TestCase, TestPlan

extension/mod.rs (1,130 lines) → 9 groups

rename/mod.rs (1,912 lines) → 9 groups

How It Works

The key insight is that orchestrator functions (those that call 4+ other functions in the same file) create transitive closure in union-find. By excluding hub edges:

1. Leaf helper clusters form naturally (2-3 tightly coupled functions)
2. Hub functions fall through to name-based clustering where they group with similarly-named peers
3. No single group absorbs the majority of the file's functions

Note

The Rust grammar parser currently only matches pub and pub(crate) function visibility — pub(super) and private functions with complex signatures may not be parsed. This limits decompose to ~20 of ~30 items in contract_testgen.rs. That's a separate grammar issue (#818 scope).

Related

• audit: god file in homeboy (20) #536 (god file audit findings)
• refactor: split contract_testgen.rs (3k lines) into submodule directory #946 (contract_testgen.rs split)
• refactor: extract logic from extension/mod.rs into dedicated submodules #947 (extension/mod.rs split)
• refactor: split rename/mod.rs (1.9k lines) into focused submodules #948 (rename/mod.rs split)

[homeboy-ci]

Homeboy Results — homeboy

Lint

Failure Digest

Lint Failure Digest

• No structured lint details available.
• Full lint log: https://github.com/Extra-Chill/homeboy/actions/runs/23422090858

Autofixability classification

• Overall: auto_fixable
• Autofix enabled: yes
• Autofix attempted this run: no
• Auto-fixable failed commands:
  • lint
• Failed commands with available automated fixes:
  • lint

Machine-readable artifacts

• homeboy-lint-summary.json
• homeboy-test-failures.json
• homeboy-audit-summary.json
• homeboy-autofixability.json

⚡ Scope: changed files only

❌ lint (changed files only)

Audit

⚡ Scope: changed files only

✅ audit (changed files only)

Auto-refactor

ℹ️ Autofix enabled, but no fixable file changes were produced

Failure Digest

Autofixability classification

• Overall: human_needed
• Autofix enabled: yes
• Autofix attempted this run: no
• Human-needed failed commands:
  • refactor --from all

Machine-readable artifacts

• homeboy-lint-summary.json
• homeboy-test-failures.json
• homeboy-audit-summary.json
• homeboy-autofixability.json

⚡ Scope: changed files only

❌ refactor --from all

Tooling versions

• Homeboy CLI: homeboy 0.85.3+a5999fe
• Extension: rust from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: unknown
• Action: Extra-Chill/homeboy-action@v2

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Homeboy Action v1