Onboard — codebase orientation tour

Run an extend op for a developer entering an unfamiliar repository. Extend their working context with a compact, evidence-backed map: what the project is, where execution starts, what areas are active, which commands are real, and which 2-3 files to read first.

The output is not a repo summary dump. It is an orientation artifact followed by an ask decision: explore an area, trace a feature, make a first change, or find where help is useful.

When to Apply / NOT

Apply:

• New repository, context switch, unfamiliar PR, or implementation planning before touching code.
• User asks for a tour, starting point, orientation, project summary, or "where do I begin?".
• A local checkout exists, even if it is not a git repo.

NOT:

• User already named a concrete bug or failing test — orient only if the fix path is unclear.
• User wants a full architectural critique, security audit, or performance investigation.
• User asks for exhaustive symbol indexing. Onboard is bounded by depth and optimized for first useful map.

Inputs

• path: repository root; default current working directory.
• depth: quick | normal | deep; default normal.
• Optional focus: area, feature, language, package, or entry point. Focus constrains the deep-read and follow-up guidance, not the initial collection contract.

Workflow

1. Parse scope and depth

Normalize the root path first. Reject nonexistent paths. Preserve the requested depth in the output header.

Depth controls collection cost only; the synthesized orientation always uses the same seven sections.

2. Collect bounded context

Collect facts before explaining. Never fabricate a section from filenames alone. Use this native order:

1. Manifest parse. Inspect root manifests and workspace manifests:

• JavaScript / TypeScript: package.json, pnpm-workspace.yaml, lerna.json, turbo.json, nx.json.
• Rust: Cargo.toml, [workspace], crates/*/Cargo.toml.
• Go: go.mod, go.work, cmd/*, Makefile targets.
• Python: pyproject.toml, setup.py, requirements*.txt, tox.ini, noxfile.py, libs/*/pyproject.toml, packages/*/pyproject.toml.
• Java / JVM: pom.xml, .mvn/, build.gradle, build.gradle.kts, settings.gradle, settings.gradle.kts.
• Build-only fallback: Makefile, CMakeLists.txt, meson.build, configure.ac.

1. Structure walk, max depth 3. Prefer ODIN find; headless equivalent:

fd -d 3 -t d . "$ROOT" -E node_modules -E .git -E dist -E target -E out -E .next -E .nuxt -E __pycache__ -E coverage -E .cache -E vendor. If fd is absent: find "$ROOT" -maxdepth 3 -type d \( -name node_modules -o -name .git -o -name dist -o -name target -o -name out -o -name .next -o -name .nuxt -o -name __pycache__ -o -name coverage -o -name .cache -o -name vendor \) -prune -o -type d -print.

1. README and local rules. Read README*, CLAUDE.md, and AGENTS.md, capped at about 5KB each. Follow a one-line README redirect if it points to another Markdown file.
2. CI and runtime services. Inspect .github/workflows/*.{yml,yaml}, .gitlab-ci.yml, Dockerfile, docker-compose*.yml, Procfile, compose.yaml, and deploy manifests present at the root.
3. Git info. If git exists, collect branch, remote, commit count, last commit, shallow status, recent owners, and hotspots:

• git rev-parse --show-toplevel
• git branch --show-current
• git rev-list --count HEAD
• git log -1 --format='%ci %h %s'
• git remote get-url origin
• git shortlog -sn --all -- .
• git --no-pager log --since='180 days ago' --format='' --name-only -- .

1. Native signals. Prefer codegraph MCP if the repo is indexed:

• Entry points and execution surfaces: codegraph_explore("entry points main binaries commands framework configs tests").
• Symbol lookup: codegraph_search for main, App, server, cli, route handlers, exported package entry points.
• Call flow from an entry point: codegraph_callees or codegraph_explore naming the entry symbol and likely module names.
• File inventory: codegraph_files for package/module boundaries.

If no index exists, fallback to AST and text search:

• JavaScript/TypeScript: ast-grep -p 'function main($$$) { $$$ }', ast-grep -p 'export default $$$', plus git grep -nE 'createServer|listen\(|commander|yargs|cac\(|vite|next|astro|svelte'.
• Rust: ast-grep -p 'fn main() { $$$ }', git grep -nE '^\[\[bin\]\]|^path\s*=|fn main\('.
• Go: git grep -nE '^package main$|func main\('.
• Python: git grep -nE 'if __name__ == .__main__.|console_scripts|click\.command|typer\.Typer|argparse'.
• Java/JVM: git grep -nE 'public static void main|@SpringBootApplication|application.yml|plugins \{|mainClass'.
• Tests: fd '(test|spec|_test)\.(js|jsx|ts|tsx|rs|go|py|java|kt)$' "$ROOT".

1. Whole-repo digest. Use repomix for compressed context:

• MCP: pack_codebase(directory="$ROOT", compress=true).
• CLI fallback: npx -y repomix "$ROOT" --compress -o /tmp/onboard-repomix.xml.

Use the digest to confirm stack, top-level modules, and naming conventions. Do not paste it into the final response.

3. Synthesize the seven-section orientation

Use the template in references/orientation.md. Keep the first pass concise; the target is a 2-3 minute read. Sections are ordered and named exactly:

1. What it does — one or two plain-language sentences from README + manifest.
2. Tech stack + CI — languages, framework, package manager, build/test tools, CI jobs.
3. Where execution starts — entry points grouped by kind: binaries/CLIs, server/app boot, framework-loaded config, libraries/exports, tests/benches.
4. Project structure, annotated — top directories with purpose and unusual layout notes.
5. Active development — hotspots + owners — top churn files, recent maintainers, areas under change.
6. Code health — slop/drift/test gaps only when evidence exists. Certainty grades: HIGH from tools, MEDIUM from repeated patterns, LOW from inference.
7. Getting started — exact runnable commands — clone/install/build/test/run commands copied from manifests, CI, or observed scripts.

4. Deep-read 2-3 real files

After the orientation, read actual source before claiming architecture.

Read, in priority order:

1. Primary entry point: structural entry point from codegraph/AST, package bin, Cargo [[bin]], Go cmd/*, Python console script, or framework config.
2. Largest module by file count from the 3-level structure walk.
3. One representative test file.

If fewer exist, read what exists and state the degradation. Tie the files together with file paths and concrete calls/imports. Avoid "likely" architecture except where labeled [INFERENCE].

5. Ask for the next move

Close the first turn with the ask tool. Use one axis, single-select, one Recommended option:

• explore_area — Explore an area (Recommended for first-time onboarding): pick a directory/package and read its central exports plus most-imported file.
• trace_feature — Trace a feature: ask for the feature name, locate its entry point, trace call/import flow, deep-read 2-3 key files.
• first_change — Make a first change: ask for desired change, map risk using hotspots/owners/tests, identify exact files to inspect before editing.
• where_help — Where can I help?: combine hotspots, test gaps, stale docs, low-owner areas, and small cleanup candidates into file-level recommendations.

If the ask tool is unavailable in the current harness, present the same four options as a numbered prompt and stop after the question.

Anti-patterns

• Raw JSON dump: collection output is evidence, not user-facing text.
• Filename architecture: never explain flow before reading source.
• Exhaustive tree spam: annotate structure; do not paste a directory listing.
• Command invention: runnable commands come from manifests, CI, Makefile, or README. Otherwise mark [INFERENCE] and prefer no command.
• Repo-health moralizing: code health helps a newcomer steer. It is not a cleanup assignment unless the user chooses that path.
• Cross-tool cache dependency: no external analyzer binary or persistent intelligence cache. Recompute signals natively.

Validation Gates

Degradation

Use explicit certainty labels. HIGH means observed by tool output. MEDIUM means multiple independent weak signals. LOW means local inference required. Missing data is reported once at the affected section, not repeated throughout the tour.