debtector 0.4.1

Coupling guardrail for CI/PR: detects cycles, god modules and coupling regressions before merge

Debtector

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Coupling guardrail for CI/PR. Debtector indexes a code repository as a graph in SQLite, computes structural coupling metrics (Ca, Ce, instability, cycles, god modules) and behavioral ones (churn, hotspots, temporal coupling, bus factor), and blocks merges when metrics regress.

ICP: dev/tech lead using code agents. Agents generate hidden coupling faster than any human can track; Debtector acts as an architectural guardrail in the pipeline.

# Full report: structural coupling + git history
debtector report

# Typical CI flow: index, save baseline, check for regressions
debtector index ./src
debtector baseline save
debtector baseline status   # exit 1 if new cycles or coupling worsens

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Installation

Debtector is a command-line tool, not a library. Install it globally to use it across projects.

With uv (recommended)

uv tool install /path/to/codeIndex

uv tool install does not support editable mode. To reflect code changes, reinstall with --force (it's fast):

uv tool install /path/to/codeIndex --force

With pip

# Standard installation
pip install /path/to/codeIndex

# Editable — code changes are reflected immediately without reinstalling
pip install -e /path/to/codeIndex

Verify it is available globally:

debtector --help
which debtector

Requirements: Python ≥ 3.12

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Quick start

# 1. Index the project (incremental: only re-parses changed files)
debtector index ./src

# 2. View structural coupling
debtector coupling

# 3. View git history metrics (hotspots, temporal coupling, bus factor)
debtector git-coupling

# 4. Full report (structural + behavioral)
debtector report

# 5. Save baseline (commit .debtector/baseline.json to the repo)
debtector baseline save
git add .debtector/baseline.json && git commit -m "chore: save metrics baseline"

# 6. In CI: verify metrics have not regressed
debtector baseline status

Note: analysis commands (coupling, git-coupling, report, impact, etc.) silently auto-index if there are modified files. There is no need to run index manually in the normal workflow.

The index lives in .debtector/index.db. The baseline in .debtector/baseline.json. Logs in .debtector/debtector.log.

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Commands

Indexing

Command	Description
index <dir>	Index the directory (incremental by SHA-256 hash)
status	Graph statistics (files, nodes, edges by type)

Code analysis

Command	Description
search <query>	Search symbols by name (FTS5 + BM25). --kind Class|Function|Method to filter
summary <file>	All symbols and imports in a file
impact <files...>	Which files and nodes are affected by a change. --depth N
imports <module>	Which files import a module or library
callers <qname>	Which functions/methods call a specific symbol
untested [path]	Production symbols with no test coverage

Structural coupling

Command	Description
coupling	Ca, Ce, I table per module + cycles + god modules. --sort fan_in|fan_out|instability, --limit N, --json
baseline save	Save metrics snapshot to .debtector/baseline.json
baseline status	Compare current metrics against the baseline. Exit 1 on regressions (configurable)
baseline status --reporter github	Same but emits GitHub Actions Annotations (::error/::warning)
baseline status --reporter gitlab	Same but emits GitLab CI section markers

Behavioral coupling (git history)

Command	Description
hotspots	Technical debt ranking: churn × (fan_in + fan_out). --limit N, --since DATE
temporal-coupling	File pairs that change together without a direct import. --min-shared N, --min-ratio F, --since DATE
bus-factor	Knowledge concentration risk: % of lines by dominant author. --limit N
git-coupling	Aggregated view of the three above. --json combines all three sections
report	Full report: structural + behavioral coupling. --json for AI/CI consumption

Configuration and hooks

Command	Description
install-hook	Git pre-commit hook for auto-indexing
install-skill	Claude Code skills for using the graph in AI context

Global flag --json

All commands support --json to emit compact JSON to stdout, suitable for direct consumption by AI agents or pipelines:

debtector --json coupling
debtector --json report
debtector --json hotspots --limit 10
debtector --json baseline status
debtector --json search "AuthService"

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Available metrics

Structural coupling (debtector coupling)

Metric	Description
Ca (fan-in)	How many modules depend on this one. Weight 1.0 per IMPORTS_FROM and USES_TYPE
Ce (fan-out)	How many modules this one imports. Same weight scheme
I (instability)	Ce / (Ca + Ce). 0 = very stable, 1 = very unstable

Example output:

Module                      Ca      Ce       I    Flags
──────────────────────────────────────────────────────
src/graph_store.py        12.0     3.0   0.200
src/cli.py                 0.0    14.5   1.000  ⚠ unstable
src/models.py              9.5     0.0   0.000  ● god
──────────────────────────────────────────────────────
Total: 8 modules

✓  No cycles
● God modules (Ca > p90): src/models.py

Cycles

Import cycle detection using Tarjan's algorithm (SCCs). Considers IMPORTS_FROM and CALLS edges.

God modules

Modules whose fan-in exceeds the 90th percentile of the project. Relative threshold, not absolute.

Inheritance (debtector coupling --json)

Inheritance hierarchy depth and number of direct children per class.

Behavioral coupling (debtector git-coupling)

Metric	Description
Hotspot score	churn × (fan_in + fan_out). The most changed and most coupled modules carry the highest technical debt risk
Temporal coupling	File pairs that appear together in commits more frequently than a configurable threshold, even without a direct import between them
Bus factor	Minimum number of authors needed to cover 80% of the lines in a file. 1 = single point of failure

Example output of debtector hotspots:

Module                            Churn  Coupling     Score
────────────────────────────────────────────────────────────
src/graph_store.py                   47      15.00    705.00
src/cli.py                           31      14.50    449.50
src/parser/python_parser.py          28       3.00     84.00
────────────────────────────────────────────────────────────
Total: 8 hotspots

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Ratcheting in CI

The typical CI flow is:

# .github/workflows/ci.yml
- name: Check coupling ratchet
  run: |
    debtector index ./src
    debtector baseline status --reporter github

• If baseline.json does not exist → exit 0 (silent mode, does not block)
• If it exists and metrics are equal or improve → exit 0
• If there are new cycles, new god modules, or instability worsens → exit 1

Severity configuration (debtector.toml)

[metrics.thresholds]
god_module_percentile = 90    # percentile for god module
instability_threshold = 0.8   # I >= threshold → warning in table

[metrics.severity]
cycles      = "error"    # blocks CI
god_modules = "warning"  # warns but does not block
instability = "warning"  # warns but does not block
inheritance = "info"     # info only

Severities: error (exit 1) · warning (prints, exit 0) · info (silent, exit 0).

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Supported languages

Language	Extensions
Python	.py
JavaScript	.js, .jsx
TypeScript	.ts, .tsx

---

Graph edge types

Type	Description
CONTAINS	File → class/function
HAS_METHOD	Class → method
IMPORTS_FROM	File → imported module (weight 1.0 in Ca/Ce)
INHERITS	Class → base class
CALLS	Function/method → called function/method
COVERS	Test function → production symbol it exercises
USES_TYPE	Function → type referenced in type hints (weight 1.0 in Ca/Ce)

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.debtector/ directory

.debtector/
  index.db        # SQLite graph (committable if you want to share it)
  baseline.json   # metrics snapshot (commit to repo)
  debtector.log   # structured logs (git-ignored)
  .gitignore      # auto-generated

The .debtector/.gitignore is managed by Debtector: ignores everything except baseline.json and the .gitignore itself.

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Auto-indexing with git hook

debtector install-hook              # re-indexes on each pre-commit
debtector install-hook --add-to-stage  # also stages index.db

The hook is incremental (only re-parses files with a different hash) and never blocks a commit.

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Claude Code integration

debtector install-skill --global   # installs in ~/.claude/skills/
debtector install-skill            # installs in .claude/skills/ of the project

With the skills installed, Claude Code recognizes phrases like "analyze the impact of changing AuthService" or "who imports flask?" and automatically calls the CLI with --json.

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Development

git clone https://github.com/aitormf/codeIndex
cd codeIndex
uv sync --dev

uv run pytest                     # tests
uv run ruff check .               # linter
uv run ruff format .              # formatter
uv run bandit -r src/             # security

# Install pre-commit hooks (three stages required)
uv run pre-commit install
uv run pre-commit install --hook-type commit-msg
uv run pre-commit install --hook-type pre-push

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Logging

DEBTECTOR_LOG_JSON=false debtector index ./src   # colored (default)
DEBTECTOR_LOG_JSON=true  debtector index ./src   # JSON lines (prod/observability)

Logs always go to .debtector/debtector.log, never to stdout.

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Roadmap

• FTS5 — lexical/ranked search
• CALLS — intra-file call edges
• COVERS + debtector untested — test coverage
• .debtectorignore — additional ignored paths
• Ca, Ce, instability — coupling metrics per module
• Cycles — detection with Tarjan's algorithm
• God modules — fan-in outliers (90th percentile)
• Inheritance — depth and number of children
• USES_TYPE — type hint coupling (weight 1.0)
• debtector coupling — tabular output with flags (formerly metrics)
• Baseline + ratcheting — CI only fails if metrics worsen
• Configurable severity — debtector.toml error/warning/info per type
• CI reporter — GitHub Annotations + GitLab CI section markers
• Silent auto-index — analysis commands index before executing
• Hotspots — churn × structural coupling; real technical debt ranking
• Temporal coupling — files that co-change without a direct import
• Bus factor — knowledge concentration risk per file
• debtector git-coupling / report — aggregated behavioral and full views
• Graph diff — metric delta between base branch and PR
• GitHub Action — automatic comment on PRs
• More languages — Go, Rust, Java

License

AGPL-3.0 — see LICENSE.