diff --git a/.beads/interactions.jsonl b/.beads/interactions.jsonl
index b772f40..867a339 100644
--- a/.beads/interactions.jsonl
+++ b/.beads/interactions.jsonl
@@ -7,3 +7,8 @@
 {"id":"int-3e1630bd","kind":"field_change","created_at":"2026-04-07T12:38:16.042213Z","actor":"Ken Judy","issue_id":"code-quality-metrics-h22","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"lint clean, typecheck clean, 117/117 tests, 96.21% lines / 96.42% functions — all thresholds met"}}
 {"id":"int-cee835a3","kind":"field_change","created_at":"2026-04-07T12:38:16.543793Z","actor":"Ken Judy","issue_id":"code-quality-metrics-oga","extra":{"field":"status","new_value":"closed","old_value":"open","reason":"All 7 implementation steps complete. Formula fixed, fields renamed, spec updated, tests green."}}
 {"id":"int-d7bd06be","kind":"field_change","created_at":"2026-04-07T12:41:46.049872Z","actor":"Ken Judy","issue_id":"code-quality-metrics-zx6","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Both workflow files updated: formula fixed (bounded), fields renamed to net_additions_ratio_*, thresholds updated to <0.50, display labels updated. Also cleaned up redundant sort+map in code-metrics.yml ratioStats computation."}}
+{"id":"int-8c6635bc","kind":"field_change","created_at":"2026-04-07T13:28:25.173297Z","actor":"Ken Judy","issue_id":"code-quality-metrics-2hj","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"isTestFile moved to lib/metrics.js, re-exported from lib/git.js. 119/119 tests pass."}}
+{"id":"int-94ca1d4f","kind":"field_change","created_at":"2026-04-07T13:33:11.382272Z","actor":"Ken Judy","issue_id":"code-quality-metrics-bul","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"code-metrics.yml refactored: inline helpers removed, require() added, CONFIG.* used for all thresholds, velocity_commits_per_day added, classifyDoraArchetype signature fixed"}}
+{"id":"int-5369ba6b","kind":"field_change","created_at":"2026-04-07T13:33:11.931574Z","actor":"Ken Judy","issue_id":"code-quality-metrics-a6p","extra":{"field":"status","new_value":"closed","old_value":"open","reason":"pr-metrics.yml refactored: inline helpers removed, require() added, isTestFile() replaces 4x regex, CONFIG.* thresholds, classifyDoraArchetype signature fixed"}}
+{"id":"int-7a66b645","kind":"field_change","created_at":"2026-04-07T13:34:14.142186Z","actor":"Ken Judy","issue_id":"code-quality-metrics-ac0","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"CLAUDE.md updated: architecture section reflects shared lib/, config section notes single source of truth, 'update both places' warning removed, net additions ratio threshold updated"}}
+{"id":"int-6b197fa6","kind":"field_change","created_at":"2026-04-07T13:34:39.195467Z","actor":"Ken Judy","issue_id":"code-quality-metrics-22h","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"lint clean, typecheck clean, 119/119, 96.21%/96.42% coverage — all thresholds met"}}
diff --git a/.github/workflows/code-metrics.yml b/.github/workflows/code-metrics.yml
index 4ae970f..5b68ae2 100644
--- a/.github/workflows/code-metrics.yml
+++ b/.github/workflows/code-metrics.yml
@@ -30,60 +30,10 @@ jobs:
         with:
           script: |
             const fs = require('fs');
-
-            // ---------------------------------------------------------------
-            // Inline helpers (mirrors local-code-metrics.js logic)
-            // ---------------------------------------------------------------
-
-            const CONVENTIONAL_COMMIT_RE = /^(feat|fix|refactor|test|chore|docs|perf|ci|build|revert)(\(.+\))?:/i;
-            function scoreMessageQuality(message) {
-              if (!message) return false;
-              if (CONVENTIONAL_COMMIT_RE.test(message)) return true;
-              return message.split(/\s+/).filter(Boolean).length >= 10;
-            }
-
-            function quantile(sorted, p) {
-              if (sorted.length === 0) return 0;
-              if (sorted.length === 1) return sorted[0];
-              const idx = p * (sorted.length - 1);
-              const lo = Math.floor(idx);
-              const hi = Math.ceil(idx);
-              return sorted[lo] + (sorted[hi] - sorted[lo]) * (idx - lo);
-            }
-
-            function computeStats(values) {
-              if (values.length === 0) return { p50: 0, p90: 0, p95: 0, mean: 0, stddev: 0 };
-              const sorted = [...values].sort((a, b) => a - b);
-              const mean = values.reduce((s, v) => s + v, 0) / values.length;
-              const variance = values.reduce((s, v) => s + (v - mean) ** 2, 0) / values.length;
-              return {
-                p50: quantile(sorted, 0.5),
-                p90: quantile(sorted, 0.9),
-                p95: quantile(sorted, 0.95),
-                mean,
-                stddev: Math.sqrt(variance)
-              };
-            }
-
-            function computeVelocityTrend(timestamps) {
-              if (timestamps.length < 2) return 'stable';
-              const ms = timestamps.map(t => new Date(t).getTime()).sort((a, b) => a - b);
-              const spanDays = (ms[ms.length - 1] - ms[0]) / 86400000 || 1;
-              const midMs = (ms[0] + ms[ms.length - 1]) / 2;
-              const halfSpan = spanDays / 2 || 1;
-              const firstRate = ms.filter(t => t <= midMs).length / halfSpan;
-              const secondRate = ms.filter(t => t > midMs).length / halfSpan;
-              if (secondRate > firstRate * 1.25) return 'accelerating';
-              if (secondRate < firstRate * 0.75) return 'decelerating';
-              return 'stable';
-            }
-
-            function classifyDoraArchetype(large, sprawling, testFirst, msgQuality) {
-              if (large < 20 && sprawling < 10 && testFirst > 50 && msgQuality > 60) return 'harmonious-high-achiever';
-              if (sprawling > 25 && large > 30) return 'legacy-bottleneck';
-              if (large > 40 || (testFirst < 30 && large > 20)) return 'foundational-challenges';
-              return 'mixed-signals';
-            }
+            // lib/ modules are available after checkout — require() resolves from $GITHUB_WORKSPACE
+            const { CONFIG } = require('./lib/config');
+            const { computeStatistics, computeVelocity } = require('./lib/statistics');
+            const { scoreMessageQuality, classifyDoraArchetype, isTestFile } = require('./lib/metrics');
 
             // ---------------------------------------------------------------
             // Main collection
@@ -91,7 +41,7 @@ jobs:
 
             async function collectMetrics() {
               const [owner, repo] = process.env.GITHUB_REPOSITORY.split('/');
-              const since = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000).toISOString();
+              const since = new Date(Date.now() - CONFIG.ANALYSIS_DAYS * 24 * 60 * 60 * 1000).toISOString();
 
               console.log(`Repository: ${owner}/${repo}`);
               console.log(`Looking for commits since: ${since}`);
@@ -165,6 +115,7 @@ jobs:
                     p90_lines_changed: 0,
                     p95_lines_changed: 0,
                     stddev_lines_changed: 0,
+                    velocity_commits_per_day: 0,
                     velocity_trend: "stable",
                     net_additions_ratio_median: 0,
                     net_additions_ratio_p90: 0,
@@ -178,9 +129,9 @@ jobs:
                 }
 
                 const metrics = [];
-                console.log(`Processing ${Math.min(uniqueCommits.length, 50)} commits...`);
+                console.log(`Processing ${Math.min(uniqueCommits.length, CONFIG.MAX_COMMITS)} commits...`);
 
-                for (const commit of uniqueCommits.slice(0, 50)) {
+                for (const commit of uniqueCommits.slice(0, CONFIG.MAX_COMMITS)) {
                   try {
                     const detail = await github.rest.repos.getCommit({
                       owner,
@@ -188,13 +139,8 @@ jobs:
                       ref: commit.sha
                     });
 
-                    const testFiles = detail.data.files?.filter(f =>
-                      /\.(test|spec)\.|Tests?\.cs$|Test\.cs$|__tests__|\/tests?\//i.test(f.filename)
-                    ) || [];
-
-                    const prodFiles = detail.data.files?.filter(f =>
-                      !/\.(test|spec)\.|Tests?\.cs$|Test\.cs$|__tests__|\/tests?\//i.test(f.filename)
-                    ) || [];
+                    const testFiles = detail.data.files?.filter(f => isTestFile(f.filename)) || [];
+                    const prodFiles = detail.data.files?.filter(f => !isTestFile(f.filename)) || [];
 
                     const message = commit.commit.message.split('\n')[0];
 
@@ -212,8 +158,8 @@ jobs:
                       test_first_indicator: testFiles.length > 0 && prodFiles.length > 0,
                       prod_additions: prodFiles.reduce((sum, f) => sum + f.additions, 0),
                       prod_deletions: prodFiles.reduce((sum, f) => sum + f.deletions, 0),
-                      large_commit: (prodFiles.reduce((sum, f) => sum + f.additions + f.deletions, 0)) > 100,
-                      sprawling_commit: (detail.data.files?.length || 0) > 5,
+                      large_commit: (prodFiles.reduce((sum, f) => sum + f.additions + f.deletions, 0)) > CONFIG.LARGE_COMMIT_THRESHOLD,
+                      sprawling_commit: (detail.data.files?.length || 0) > CONFIG.SPRAWLING_COMMIT_THRESHOLD,
                       message_quality: scoreMessageQuality(message),
                       commit_type: "feature_branch"
                     });
@@ -228,15 +174,16 @@ jobs:
                 fs.writeFileSync('commit_metrics.json', JSON.stringify(metrics, null, 2));
 
                 // Statistical distributions
+                const timestamps = metrics.map(m => new Date(m.date).getTime());
                 const lineSizes = metrics.map(m => m.total_additions + m.total_deletions);
-                const lineStats = computeStats(lineSizes);
-                const fileStats = computeStats(metrics.map(m => m.files_changed));
+                const lineStats = computeStatistics(lineSizes, timestamps);
+                const fileStats = computeStatistics(metrics.map(m => m.files_changed), timestamps);
                 const ratios = metrics.map(m => {
                   const t = m.total_additions + m.total_deletions;
                   return t === 0 ? 0 : (m.total_additions - m.total_deletions) / t;
                 });
-                const ratioStats = computeStats(ratios);
-                const velocityTrend = computeVelocityTrend(metrics.map(m => m.date));
+                const ratioStats = computeStatistics(ratios, timestamps);
+                const velocity = computeVelocity(metrics.map(m => m.date));
 
                 const qualityCount = metrics.filter(m => m.message_quality).length;
                 const msgQualityPct = metrics.length > 0
@@ -264,11 +211,12 @@ jobs:
                   stddev_lines_changed: Math.round(lineStats.stddev),
                   p50_files_changed: Math.round(fileStats.p50),
                   p90_files_changed: Math.round(fileStats.p90),
-                  velocity_trend: velocityTrend,
+                  velocity_commits_per_day: velocity.commits_per_day,
+                  velocity_trend: velocity.trend,
                   net_additions_ratio_median: parseFloat(ratioStats.p50.toFixed(2)),
                   net_additions_ratio_p90: parseFloat(ratioStats.p90.toFixed(2)),
                   message_quality_pct: msgQualityPct,
-                  dora_archetype: classifyDoraArchetype(largePct, sprawlingPct, testFirstPct, parseFloat(msgQualityPct)),
+                  dora_archetype: classifyDoraArchetype({ large_commits_pct: largePct.toFixed(2), sprawling_commits_pct: sprawlingPct.toFixed(2), test_first_pct: testFirstPct.toFixed(2), message_quality_pct: msgQualityPct }),
                   note: "Feature branches only - main/master excluded. Large commit threshold applied to production code only."
                 };
 
diff --git a/.github/workflows/pr-metrics.yml b/.github/workflows/pr-metrics.yml
index 489cc79..36bf056 100644
--- a/.github/workflows/pr-metrics.yml
+++ b/.github/workflows/pr-metrics.yml
@@ -17,23 +17,9 @@ jobs:
           script: |
             const pr = context.payload.pull_request;
 
-            // ---------------------------------------------------------------
-            // Inline helpers (mirrors local-code-metrics.js logic)
-            // ---------------------------------------------------------------
-
-            const CONVENTIONAL_COMMIT_RE = /^(feat|fix|refactor|test|chore|docs|perf|ci|build|revert)(\(.+\))?:/i;
-            function scoreMessageQuality(message) {
-              if (!message) return false;
-              if (CONVENTIONAL_COMMIT_RE.test(message)) return true;
-              return message.split(/\s+/).filter(Boolean).length >= 10;
-            }
-
-            function classifyDoraArchetype(large, sprawling, testFirst, msgQuality) {
-              if (large < 20 && sprawling < 10 && testFirst > 50 && msgQuality > 60) return 'harmonious-high-achiever';
-              if (sprawling > 25 && large > 30) return 'legacy-bottleneck';
-              if (large > 40 || (testFirst < 30 && large > 20)) return 'foundational-challenges';
-              return 'mixed-signals';
-            }
+            // lib/ modules are available after checkout — require() resolves from $GITHUB_WORKSPACE
+            const { CONFIG } = require('./lib/config');
+            const { scoreMessageQuality, classifyDoraArchetype, isTestFile } = require('./lib/metrics');
 
             // ---------------------------------------------------------------
             // Fetch PR data
@@ -55,13 +41,8 @@ jobs:
 
             console.log(`Analyzing ${commits.length} commits and ${files.length} files in PR`);
 
-            const testFiles = files.filter(f =>
-              /\.(test|spec)\.|Tests?\.cs$|Test\.cs$|__tests__|\/tests?\//i.test(f.filename)
-            );
-
-            const prodFiles = files.filter(f =>
-              !/\.(test|spec)\.|Tests?\.cs$|Test\.cs$|__tests__|\/tests?\//i.test(f.filename)
-            );
+            const testFiles = files.filter(f => isTestFile(f.filename));
+            const prodFiles = files.filter(f => !isTestFile(f.filename));
 
             // ---------------------------------------------------------------
             // Per-commit analysis
@@ -76,13 +57,8 @@ jobs:
                   ref: commit.sha
                 });
 
-                const commitTestFiles = detail.data.files?.filter(f =>
-                  /\.(test|spec)\.|Tests?\.cs$|Test\.cs$|__tests__|\/tests?\//i.test(f.filename)
-                ) || [];
-
-                const commitProdFiles = detail.data.files?.filter(f =>
-                  !/\.(test|spec)\.|Tests?\.cs$|Test\.cs$|__tests__|\/tests?\//i.test(f.filename)
-                ) || [];
+                const commitTestFiles = detail.data.files?.filter(f => isTestFile(f.filename)) || [];
+                const commitProdFiles = detail.data.files?.filter(f => !isTestFile(f.filename)) || [];
 
                 const prodChanges = commitProdFiles.reduce((sum, f) => sum + f.additions + f.deletions, 0);
                 const testChanges = commitTestFiles.reduce((sum, f) => sum + f.additions + f.deletions, 0);
@@ -102,8 +78,8 @@ jobs:
                   prod_changes: prodChanges,
                   test_changes: testChanges,
                   total_changes: detail.data.stats.additions + detail.data.stats.deletions,
-                  large_commit: prodChanges > 100,
-                  sprawling_commit: (detail.data.files?.length || 0) > 5,
+                  large_commit: prodChanges > CONFIG.LARGE_COMMIT_THRESHOLD,
+                  sprawling_commit: (detail.data.files?.length || 0) > CONFIG.SPRAWLING_COMMIT_THRESHOLD,
                   test_first_indicator: commitTestFiles.length > 0 && commitProdFiles.length > 0,
                   test_only: commitTestFiles.length > 0 && commitProdFiles.length === 0,
                   prod_only: commitProdFiles.length > 0 && commitTestFiles.length === 0,
@@ -274,7 +250,7 @@ jobs:
             // ---------------------------------------------------------------
 
             const archetype = commitMetrics.length > 0
-              ? classifyDoraArchetype(largePct, sprawlingPct, testFirstPct, msgQualityPct)
+              ? classifyDoraArchetype({ large_commits_pct: largePct.toFixed(2), sprawling_commits_pct: sprawlingPct.toFixed(2), test_first_pct: testFirstPct.toFixed(2), message_quality_pct: msgQualityPct.toFixed(2) })
               : 'mixed-signals';
 
             const archetypeDescriptions = {
diff --git a/AGENTS.md b/AGENTS.md
index 35d27f5..224e831 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -132,6 +132,21 @@ npm run lint      # lint must be clean before moving to next step
 
 When introducing new tooling (new lint rules, type checking, config changes), run the gate immediately after setup — before writing any tests or code — to catch configuration gaps early.
 
+**When modifying `.github/workflows/` or `lib/`**, run a workflow smoke test:
+
+```bash
+gh workflow run code-metrics.yml --ref <your-branch>
+gh run watch                          # wait for completion
+gh run download <run-id> --dir /tmp/smoke && cat /tmp/smoke/*/metrics_summary.json | python3 -m json.tool
+```
+
+Verify:
+- The artifact contains `velocity_commits_per_day` (numeric, not absent)
+- No `Cannot find module` errors in the log
+- Confirm the run's commit SHA matches your branch HEAD: `gh run view <run-id>`
+
+A green run ≠ new code ran. The artifact is the proof.
+
 ## Landing the Plane (Session Completion)
 
 **When ending a work session**, you MUST complete ALL steps below. Work is NOT complete until `git push` succeeds.
diff --git a/CLAUDE.md b/CLAUDE.md
index 2e35596..e22804e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -40,20 +40,20 @@ npm install   # triggers `prepare`, which sets core.hooksPath to .githooks
 
 ## Architecture
 
-Three public components with no shared code between them:
+Three public components sharing pure-computation logic via `lib/`:
 
 1. **`local-code-metrics.js`**: Standalone Node.js script (requires Node ≥18). Orchestration entry point that delegates to focused modules in `lib/`. Reads local git history via shell commands, classifies files as test vs. production, computes metrics, writes `local_commit_metrics.json` + `local_metrics_summary.json` + (optionally) `local_claude_analysis.json`, and prints a console report with insights.
 
-   The `lib/` directory contains the internal modules (not shared with workflows):
-   - `lib/config.js` — CONFIG object; single source of truth for all thresholds
-   - `lib/git.js` — git shell commands, log parsing, per-commit analysis, diff extraction
-   - `lib/statistics.js` — statistical distributions (p50/p90/p95/stddev), velocity and trend
-   - `lib/metrics.js` — message quality scoring, DORA archetype classification, insights generation
-   - `lib/claude.js` — Anthropic client setup, commit pre-filtering, diff-level API analysis
+   The `lib/` directory contains the internal modules:
+   - `lib/config.js` — CONFIG object; single source of truth for all thresholds (**shared with workflows**)
+   - `lib/statistics.js` — statistical distributions (p50/p90/p95/stddev), velocity and trend (**shared with workflows**)
+   - `lib/metrics.js` — message quality scoring, DORA archetype classification, test file detection, insights generation (**shared with workflows**)
+   - `lib/git.js` — git shell commands, log parsing, per-commit analysis, diff extraction (local only — workflows use REST API)
+   - `lib/claude.js` — Anthropic client setup, commit pre-filtering, diff-level API analysis (local only — workflows use GitHub-managed auth)
 
-2. **`.github/workflows/code-metrics.yml`**: Weekly GitHub Actions workflow. Uses the GitHub API to analyze feature branches from the past 30 days. Outputs a JSON artifact and creates a GitHub issue with the summary.
+2. **`.github/workflows/code-metrics.yml`**: Weekly GitHub Actions workflow. Uses the GitHub API to analyze feature branches from the past 30 days. Requires `lib/config.js`, `lib/statistics.js`, and `lib/metrics.js` via `require()`. Outputs a JSON artifact and creates a GitHub issue with the summary.
 
-3. **`.github/workflows/pr-metrics.yml`**: Per-PR GitHub Actions workflow. Posts a detailed comment on each PR with commit-by-commit analysis, test adequacy, and development pattern detection.
+3. **`.github/workflows/pr-metrics.yml`**: Per-PR GitHub Actions workflow. Requires `lib/config.js` and `lib/metrics.js` via `require()`. Posts a detailed comment on each PR with commit-by-commit analysis, test adequacy, and development pattern detection.
 
 ## Key Metrics and Thresholds
 
@@ -64,7 +64,7 @@ Three public components with no shared code between them:
 | Test-to-production ratio | 0.5–2.0:1 |
 | Avg files changed per commit | <5 |
 | Commit message quality % | >60% |
-| Additions-to-deletions ratio (median) | <3.0 |
+| Net additions ratio (median) | <0.50 |
 
 Statistical distributions (p50/p90/p95/stddev) are computed for lines changed and files changed. Commit velocity trend and DORA team archetype are included in the summary.
 
@@ -91,7 +91,7 @@ The script degrades gracefully when the key is absent. No SDK install is require
 
 ## Configuration
 
-Thresholds are configured in the `CONFIG` object in `lib/config.js`, which is the single source of truth for the local script. Key values:
+Thresholds are configured in the `CONFIG` object in `lib/config.js`, which is the single source of truth for **all three components**. The GitHub Actions workflows `require('./lib/config')` directly — changing a value in `lib/config.js` propagates automatically to the local script and both workflows. No manual synchronization needed. Key values:
 
 | Key | Default | Description |
 |-----|---------|-------------|
@@ -102,9 +102,7 @@ Thresholds are configured in the `CONFIG` object in `lib/config.js`, which is th
 | `AI_DIFF_MAX_CHARS` | 4000 | Diff truncation limit for Claude API calls |
 | `AI_RISK_ADDITIONS_RATIO` | 3 | Additions/deletions multiplier for Claude pre-filter |
 
-The GitHub workflows have equivalent values hard-coded in their shell/jq logic. When adjusting thresholds, update both places.
-
-Test file detection uses patterns for JS, Python, Go, Java, and C#. Extend `TEST_FILE_PATTERNS` in `lib/config.js` or the equivalent grep patterns in the workflows for other languages.
+Test file detection uses patterns for JS, Python, Go, Java, and C#. Extend `TEST_FILE_PATTERNS` in `lib/config.js` — the change propagates automatically to all three components.
 
 ## Workflow Permissions
 
diff --git a/README.md b/README.md
index 6053ae2..a8c0c31 100644
--- a/README.md
+++ b/README.md
@@ -29,19 +29,48 @@ Research shows that AI coding tools can lead to increased batch sizes, reduced r
 ## Quick Start
 
 ### Option 1: GitHub Actions (Recommended)
+
+**Step 1 — Copy the workflow files and shared lib modules into your repository**
+```bash
+mkdir -p .github/workflows lib
+curl -o .github/workflows/code-metrics.yml \
+  https://raw.githubusercontent.com/stride-nyc/code-quality-metrics/main/.github/workflows/code-metrics.yml
+curl -o .github/workflows/pr-metrics.yml \
+  https://raw.githubusercontent.com/stride-nyc/code-quality-metrics/main/.github/workflows/pr-metrics.yml
+curl -o lib/config.js \
+  https://raw.githubusercontent.com/stride-nyc/code-quality-metrics/main/lib/config.js
+curl -o lib/statistics.js \
+  https://raw.githubusercontent.com/stride-nyc/code-quality-metrics/main/lib/statistics.js
+curl -o lib/metrics.js \
+  https://raw.githubusercontent.com/stride-nyc/code-quality-metrics/main/lib/metrics.js
+```
+
+> The workflows use `require('./lib/config')`, `require('./lib/statistics')`, and `require('./lib/metrics')` at runtime. These three files must be committed alongside the workflow files.
+
+**Step 2 — Create the required issue labels** (used by the weekly report)
 ```bash
-# 1. Copy workflows to your repository
-mkdir -p .github/workflows
-# Copy .github/workflows/code-metrics.yml and pr-metrics.yml from this repo
+gh label create metrics --color 0075ca --description "Code metrics reports"
+gh label create automated --color e4e669 --description "Automated workflow output"
+```
 
-# 2. Ensure feature branches aren't auto-deleted
-# Go to repo Settings > General > Pull Requests
-# Uncheck "Automatically delete head branches"
+**Step 3 — Ensure feature branches are not auto-deleted**
 
-# 3. Run manually or wait for weekly schedule
+Go to your repo **Settings → General → Pull Requests** and uncheck  
+"Automatically delete head branches" — the weekly workflow needs branches to exist to analyze them.
+
+**Step 4 — Set workflow permissions**
+
+Go to **Settings → Actions → General → Workflow permissions** and select  
+"Read and write permissions" (required for creating issues and PR comments).
+
+**Step 5 — Trigger the first run**
+```bash
 gh workflow run code-metrics.yml
+gh run watch   # follow the run live
 ```
 
+The PR analysis workflow (`pr-metrics.yml`) triggers automatically on every new or updated pull request — no manual step needed.
+
 ### Option 2: Local Analysis
 ```bash
 # 1. Clone and run
@@ -60,7 +89,7 @@ node local-code-metrics.js
 | **Sprawling Commit %** | <10% | Identifies scattered changes across files |
 | **Test-First Discipline** | >50% | Monitors TDD practices with AI tools |
 | **Message Quality %** | >60% | Conventional commits or descriptive messages |
-| **Additions/Deletions Ratio (median)** | <3.0 | Flags batch-acceptance pattern |
+| **Net Additions Ratio (median)** | <0.50 | Flags batch-acceptance pattern (bounded 0–1: 1.0 = entirely net-new code) |
 | **Avg Files Changed** | <5 | Measures development granularity |
 
 ## Real-World Example
@@ -114,7 +143,7 @@ Large commits: <20%
 Sprawling commits: <10%
 Test-first discipline: >50%
 Message quality: >60%
-Additions ratio (median): <3.0
+Net additions ratio (median): <0.33
 ```
 
 ### Warning Signs
@@ -122,7 +151,7 @@ Additions ratio (median): <3.0
 Large commits: 20-40%
 Sprawling commits: 10-25%
 Test-first discipline: 30-50%
-Additions ratio (median): 3.0-6.0
+Net additions ratio (median): 0.33-0.50
 ```
 
 ### Critical Issues
@@ -130,7 +159,7 @@ Additions ratio (median): 3.0-6.0
 Large commits: >40%
 Sprawling commits: >25%
 Test-first discipline: <30%
-Additions ratio (median): >6.0
+Net additions ratio (median): >0.50
 ```
 
 ## DORA Archetype Classification
diff --git a/__tests__/isTestFile.test.js b/__tests__/isTestFile.test.js
index c8eb338..729d527 100644
--- a/__tests__/isTestFile.test.js
+++ b/__tests__/isTestFile.test.js
@@ -2,6 +2,20 @@
 
 const { isTestFile } = require('../local-code-metrics');
 
+// isTestFile must also be available directly from lib/metrics (for workflow require() calls)
+describe('isTestFile available from lib/metrics', () => {
+  test('isTestFile is exported from lib/metrics.js', () => {
+    const { isTestFile: isTestFileFromMetrics } = require('../lib/metrics');
+    expect(typeof isTestFileFromMetrics).toBe('function');
+  });
+
+  test('isTestFile from lib/metrics behaves identically to the one from local-code-metrics', () => {
+    const { isTestFile: isTestFileFromMetrics } = require('../lib/metrics');
+    expect(isTestFileFromMetrics('src/app.test.js')).toBe(true);
+    expect(isTestFileFromMetrics('src/app.js')).toBe(false);
+  });
+});
+
 describe('isTestFile', () => {
   // --- degenerate case ---
   test('returns false for a plain production source file', () => {
diff --git a/lib/git.js b/lib/git.js
index f3c59f7..c329a8b 100644
--- a/lib/git.js
+++ b/lib/git.js
@@ -3,6 +3,7 @@
 
 const { execSync } = require('child_process');
 const { CONFIG } = require('./config');
+const { isTestFile } = require('./metrics');
 
 /**
  * Execute Git command with error handling
@@ -50,15 +51,6 @@ function parseGitLog(logOutput) {
   return commits;
 }
 
-/**
- * Check if a filename matches test file patterns
- * @param {string} filename
- * @returns {boolean}
- */
-function isTestFile(filename) {
-  return CONFIG.TEST_FILE_PATTERNS.some(pattern => pattern.test(filename));
-}
-
 /**
  * Analyze a single commit for AI drift indicators
  * @param {string} sha
diff --git a/lib/metrics.js b/lib/metrics.js
index 1b1b3c6..70b3a10 100644
--- a/lib/metrics.js
+++ b/lib/metrics.js
@@ -3,6 +3,17 @@
 
 const { CONFIG } = require('./config');
 
+/**
+ * Check if a filename matches test file patterns.
+ * Defined here (not lib/git.js) so GitHub Actions workflows can require('./lib/metrics')
+ * without pulling in child_process-dependent git functions.
+ * @param {string} filename
+ * @returns {boolean}
+ */
+function isTestFile(filename) {
+  return CONFIG.TEST_FILE_PATTERNS.some(pattern => pattern.test(filename));
+}
+
 /** @type {RegExp} */
 const CONVENTIONAL_COMMIT_RE = /^(feat|fix|refactor|test|chore|docs|perf|ci|build|revert)(\(.+\))?:/i;
 
@@ -95,4 +106,4 @@ function generateInsights(summary, metrics) {
   return { insights, warnings, recommendations };
 }
 
-module.exports = { scoreMessageQuality, classifyDoraArchetype, generateInsights };
+module.exports = { isTestFile, scoreMessageQuality, classifyDoraArchetype, generateInsights };