port

name	port
description	Port and refactor a feature from a public GitHub repo into the local codebase. Use when user wants to copy/adapt an existing implementation (auth flow, payment integration, UI component, algorithm, etc.) from another repo rather than build from scratch. Triggers on `/ck:port` or phrases like "port from", "borrow this feature", "copy from repo X".
category	Planning & Research
status	active

Port & Refactor

Purpose

Safely extract a feature from an external GitHub repository and integrate it into the current codebase. The goal is idiomatic adaptation, not blind copy-paste: matched naming, matched layering, matched dependencies, and zero dead imports.

When to Use

• User points at a public GitHub repo and asks to "port", "borrow", "lift", "adapt", or "copy" a feature.
• User runs /ck:port <github-url> [feature] with or without --improve / --compare.
• A planning step concluded that a proven open-source implementation is a better starting point than green-field code.

Do NOT use when:

• The license of the source repo forbids redistribution. Check LICENSE before any copy.
• The feature is one function call deep — just write it.
• The source is private / requires auth. Ask user to share the relevant snippet directly.

Inputs

Input	Source	Required
repo_url	$1	yes — must be https://github.com/<owner>/<name>
feature	$2	optional — free-text hint (e.g. auth, webhook-handler, Dropzone component)
mode	--improve (default) | --compare	optional

Workflow

Phase 1 — Fetch & inspect (always)

1. Validate repo_url is a public GitHub URL. If not, stop and ask user.
2. Read LICENSE via gh api repos/<owner>/<name>/contents/LICENSE or gh repo view. Flag GPL / AGPL / non-permissive licenses to user before copying anything.
3. List repo tree: gh api repos/<owner>/<name>/ck:git/trees/HEAD?recursive=1 (or shallow-clone to /tmp/port-<repo>-<sha>/ if tree is large).
4. Delegate to scout-external (or Explore) agent: locate the file(s) implementing feature. Return paths + a 1-line "what each file does" map.
5. Save inspection report to plans/<plan-name>/reports/port-<repo>-inspect.md.

Phase 2 — Compare with local codebase (always)

6. Detect local conventions: language, framework, lint config, test framework, module structure, naming (camelCase/snake_case), import style (relative/absolute), error-handling pattern. Activate code-review skill if available.
7. Diff source vs local on three axes:
   • Dependencies — what does source pull in that local doesn't? Note version skew.
   • Patterns — class vs function, hooks vs class components, sync vs async, etc.
   • Boundaries — does source assume infra (Redis, Postgres, message queue) that local lacks?
8. Write port-<repo>-compare.md with: file-level diff plan, dep deltas, refactor checklist, risk callouts.

If --compare mode: stop here. Report to user. Do not modify any local file.

Phase 3 — Port (only --improve mode)

9. Copy the identified files into the local codebase at the mirrored layer (e.g. source's lib/auth/ → local src/auth/ if that matches convention). Do NOT preserve source paths blindly.
10. Add a single-line provenance comment at the top of each ported file: // Adapted from <repo_url>@<short-sha>:<source-path> (<license>) This is the only comment you write proactively — it's load-bearing for license compliance.
11. Apply mechanical refactors:
    • Rename to match local casing.
    • Rewrite imports to local module aliases.
    • Replace source-specific dep calls with local equivalents (e.g. axios → local fetchClient).
    • Inline or remove source-specific utility wrappers that local doesn't use.
12. Update package.json / requirements.txt / equivalent only with deps the feature genuinely needs. Do not pull the source's full dep tree.

Phase 4 — Refactor for fit (only --improve mode)

13. Apply structural refactors flagged in Phase 2: error handling style, logging, types, config injection.
14. Delegate to code-reviewer agent for a pass focused on: dead code from the port, leaked source-specific assumptions, security issues (esp. unvalidated input paths from source).

Phase 5 — Verify (always when porting)

15. Run type-check / lint / build commands locally.
16. Instruct user to run /ck:test (or run tester agent) — port is not "done" until tests pass.
17. Write final report to plans/<plan-name>/reports/port-<repo>-port.md covering: files added/modified, deps added, refactors applied, remaining TODOs, license note.

Output Locations

• Inspection: plans/<plan-name>/reports/port-<repo>-inspect.md
• Comparison: plans/<plan-name>/reports/port-<repo>-compare.md
• Final port report: plans/<plan-name>/reports/port-<repo>-port.md

If no active plan, drop reports into plans/port-adhoc-<YYMMDD-HHmm>/reports/ (bash -c 'date +%y%m%d-%H%M').

Guardrails

• License first: never copy a file before reading the source repo's LICENSE. Refuse GPL/AGPL ports unless local project is also GPL/AGPL.
• Provenance: every ported file gets the Adapted from ... header. This is the one comment exception to the "no comments" project rule — it's a legal artifact, not documentation.
• No drive-by deps: only add a dependency if the ported code actually calls it after refactor. Strip source's incidental deps.
• No silent secrets: if source files reference env vars (process.env.X, os.getenv("X")), surface them in the final report — do not invent placeholder values.
• Trust local conventions over source style: if source uses tabs and local uses spaces, local wins. Same for naming, error patterns, layering.
• Sacrifice grammar for concision in reports (per project CLAUDE.md).

Related

• /ck:scout + scout-external agent — for locating files in the source repo.
• code-review skill + code-reviewer agent — Phase 4 validation.
• /ck:test — Phase 5 verification.
• git-manager agent — commit the port as a discrete commit with feat: port <feature> from <repo> message.

References

• GitHub REST API — repo contents & trees: https://docs.github.com/en/rest/repos/contents
• gh CLI manual: https://cli.github.com/manual/
• SPDX license identifiers (for the provenance header): https://spdx.org/licenses/
• Choosealicense.com compatibility matrix: https://choosealicense.com/appendix/