codebase-teach

Analyzes bounded contexts from the project's source tree, extracts domain knowledge per context, writes ai-context/features/<context>.md files, and produces teach-report.md with coverage metrics.

Triggers: /codebase-teach, teach codebase, extract domain knowledge, update feature docs, analyze bounded contexts

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Purpose

codebase-teach fills the ai-context/features/ layer with structured domain knowledge derived from reading source code. It is the deep-read complement to memory-update (which records session decisions) and memory-init (which scaffolds empty stubs). It MUST only be invoked manually by the user.

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Process

Step 0 — Load project context (non-blocking)

This step is non-blocking: any failure (missing file, unreadable file) MUST produce at most an INFO-level note. This step MUST NOT produce status: blocked or status: failed.

1. Read ai-context/stack.md — tech stack, versions, key tools.
2. Read ai-context/architecture.md — architectural decisions and rationale.
3. Read ai-context/conventions.md — naming patterns, code conventions.
4. Read the project's CLAUDE.md (at project root) and extract the ## Skills Registry section.

For each file:

• If absent: log INFO: [filename] not found — proceeding without it.
• If present: extract Last updated: or Last analyzed: date. If date is older than 30 days: log NOTE: [filename] last updated [date] — context may be stale. Consider running /memory-update or /project-analyze.

Also read project config file (config.yaml at project root) if it exists, and extract teach_max_files_per_context if present:

• If present: max_files = teach_max_files_per_context
• If absent: max_files = 10 (default)

Log: "File cap per context: [max_files] (source: config.yaml)" or "File cap per context: 10 (default)"

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Step 1 — Scan bounded contexts

Identify bounded context candidates by scanning the project directory tree at depth ≤ 2 under these root directories (in order):

1. src/ — subdirectories at depth 1 (e.g., src/auth/, src/payments/)
2. app/ — subdirectories at depth 1
3. features/ — subdirectories at depth 1
4. domain/ — subdirectories at depth 1
5. ai-context/features/ — existing feature file names (each file stem is treated as a context name)

Exclusion rules — skip directories named: shared, utils, common, lib, types, hooks, components, __tests__, test, tests, node_modules, .git

Cross-reference with existing feature files: Read the ai-context/features/ directory (if it exists) and list all .md files, excluding files whose names begin with _ (e.g., _template.md).

For each detected context candidate, build a record:

{ slug: kebab-case of directory name, dir_path, existing_feature_file: bool }

Slug convention: lowercase the directory name; replace spaces and underscores with hyphens. Example: UserProfile → user-profile, auth_service → auth-service.

If no context candidates are found:

• Log: "No bounded context directories detected."
• Write teach-report.md with a Summary noting "No bounded context directories detected" and a recommendation to run /memory-init first.
• Stop here.

If ai-context/features/ does not exist:

• Log: "INFO: ai-context/features/ not found — feature files will be created if possible."
• Note in teach-report.md: "ai-context/features/ was absent at run time. Recommend running /memory-init to scaffold the directory before re-running /codebase-teach."
• Continue processing (the skill creates the directory and files as needed).

Output: context_list = [{ slug, dir_path, existing_feature_file: bool }, ...]

Log each context found: "Detected context: [slug] — [dir_path] (feature file: [exists|absent])"

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Step 2 — Read key files per context (sequential)

Process contexts one at a time. For each context in context_list:

1. Enumerate implementation files in dir_path (recursive), filtering for file extensions: .ts, .tsx, .js, .jsx, .py, .java, .kt, .rb, .go, .ex, .exs, .cs, .rs, .php, .swift

   • Prioritize files by recency (most recently modified first)
   • Exclude files matching: *.test.*, *.spec.*, test_*, *_test.*, *.d.ts, *.min.*

2. Apply file cap: read at most max_files files. If total enumerated > max_files, log: "[slug]: [total] files found — sampling [max_files] (cap applied)"

3. For each file to read:

   • Attempt to read the file
   • If the file is binary or unreadable: skip it; record in skipped_files with reason
   • If readable: extract the following signals:
     • Business rules: explicit conditional constraints (if/when/unless logic that enforces domain rules)
     • Invariants: assertions or validation guards that are always enforced
     • Data model entities: class/struct/interface/type names with their key fields
     • Integration points: imports of external services, APIs, or infrastructure adapters

4. Accumulate: context_knowledge = { slug, rules[], invariants[], entities[], integrations[], files_read[], skipped[] }

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Step 3 — Write ai-context/features/<slug>.md

For each context processed in Step 2:

If ai-context/features/<slug>.md does not exist (or ai-context/features/ is absent):

• Create the directory if needed
• Write a new file using the six-section structure below
• All AI-generated sections receive [auto-updated] markers

If ai-context/features/<slug>.md already exists:

• Read the entire file
• Identify <!-- [auto-updated]: codebase-teach ... --> ... <!-- [/auto-updated] --> blocks
• Overwrite content only inside [auto-updated] blocks
• Preserve byte-for-byte all content outside any [auto-updated] block
• If no [auto-updated] block exists for a section, append the section at the end of the file inside a new [auto-updated] block

Six-section feature file structure:

# [Context Name] — Domain Knowledge

Last updated by: codebase-teach
Last run: YYYY-MM-DD

---

## Domain Overview

<!-- [auto-updated]: codebase-teach — last run: YYYY-MM-DD -->
[AI-extracted 2–4 sentence summary of what this bounded context does and its primary responsibilities]
<!-- [/auto-updated] -->

---

## Business Rules and Invariants

<!-- [auto-updated]: codebase-teach — last run: YYYY-MM-DD -->
[AI-extracted explicit conditional constraints and always-true invariants from the source]

- Rule: [description]
- Invariant: [description]
<!-- [/auto-updated] -->

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## Data Model Summary

<!-- [auto-updated]: codebase-teach — last run: YYYY-MM-DD -->
Key entities detected:

| Entity | Key Fields |
|--------|-----------|
| [Name] | [field1, field2, ...] |
<!-- [/auto-updated] -->

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## Integration Points

<!-- [auto-updated]: codebase-teach — last run: YYYY-MM-DD -->
External dependencies and integration touchpoints:

- [service/API name]: [what it is used for]
<!-- [/auto-updated] -->

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## Decision Log

<!-- [auto-updated]: codebase-teach — last run: YYYY-MM-DD -->
<!-- Append new AI-detected decisions below. Human entries above this marker are preserved. -->
<!-- [/auto-updated] -->

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## Known Gotchas

<!-- [auto-updated]: codebase-teach — last run: YYYY-MM-DD -->
<!-- Append new AI-detected gotchas below. Human entries above this marker are preserved. -->
<!-- [/auto-updated] -->

_template.md guard: never read, write, or treat any file whose name begins with _ as a feature context. Skip entirely.

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Step 4 — Evaluate coverage and write teach-report.md

Coverage calculation:

documented_contexts = count of contexts that have an ai-context/features/<slug>.md file after Step 3
total_contexts      = count of contexts in context_list
coverage_pct        = (documented_contexts / total_contexts) * 100   (0 if total_contexts == 0)
gap_list            = contexts in context_list where existing_feature_file was false before Step 3
                      AND no file was created in Step 3

Write teach-report.md in the project working directory root (same level as analysis-report.md). Overwrite if it exists.

# Teach Report — [Project Name]

Last run: YYYY-MM-DD
Skill: codebase-teach

## Summary

Contexts detected: [total_contexts]
Contexts documented: [documented_contexts]
Coverage: [coverage_pct]%

## Coverage

[coverage_pct]% — [documented_contexts] of [total_contexts] contexts documented.

## Gaps

Contexts detected in code but not documented in ai-context/features/:

- [context-slug] — [dir_path]

[If no gaps: "None — all detected contexts are documented."]

## Files Read

### [context-slug]
- [file path] — sampled
- [file path] — sampled
- [file path] — SKIPPED: [reason]

[Repeat for each context]

## Sections Written / Updated

- ai-context/features/[context].md — [created|updated] — sections: [list of sections written]

If ai-context/features/ was absent at run time, append to the Summary section:

Note: ai-context/features/ was absent at run time. Recommend running /memory-init to scaffold the directory before re-running /codebase-teach.

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Rules

• MUST NOT modify ai-context/stack.md, ai-context/architecture.md, ai-context/conventions.md, ai-context/known-issues.md, or ai-context/changelog-ai.md
• MUST NOT modify any file under docs/
• MUST NOT be invoked automatically by any other skill — user-initiated only
• MUST skip any file or directory whose name begins with _ in ai-context/features/
• MUST preserve all human-authored content outside [auto-updated] markers when updating existing feature files
• MUST process contexts sequentially — never in parallel
• MUST apply the teach_max_files_per_context cap (default 10) to every context
• MUST list skipped files in teach-report.md under the "Files Read" section for the relevant context
• MUST complete without error even when no bounded context directories are detected
• MUST write teach-report.md on every successful run
• [auto-updated] marker format: <!-- [auto-updated]: codebase-teach — last run: YYYY-MM-DD --> ... <!-- [/auto-updated] --> — consistent with project-analyze convention

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Output

teach-report.md (mandatory — written to project root on every run)

Required sections:

Section	Content
Summary	Contexts detected, documented, coverage %
Coverage	Percentage and ratio
Gaps	Contexts found in code but undocumented (or "None")
Files Read	Per-context list of files sampled and skipped
Sections Written / Updated	Per-feature-file: created or updated, which sections

ai-context/features/<context>.md (one per bounded context)

Written or updated during Step 3. Six sections with [auto-updated] markers on all AI-generated content.