upstream

name	upstream
description	Check upstream repo for new changes that may be worth incorporating. Use when: (1) User says /upstream (2) User asks to "check upstream" or "what changed upstream" (3) User wants to know if upstream repos have new commits (4) User asks about syncing with or pulling from upstream sources

Upstream Change Tracker

Check the upstream repo that glean derives from for new commits, classify changes by relevance, and present a summary.

Upstream Repo

Repo	Default Branch	Relationship
jahala/tilth	main	Direct fork — glean's entire Rust codebase derives from tilth

Workflow

Step 1: Read Marker File

Read .claude/skills/upstream/references/last-checked.json.

• If the file is empty or does not exist -> this is a first run. Set FIRST_RUN=true.
• If the file exists with content -> parse the JSON to get last_checked_sha and last_checked_date.

Step 2: Fetch Changes

First Run (no marker file)

Fetch the last 30 commits:

gh api "repos/jahala/tilth/commits?per_page=30&sha=main" --jq '[.[] | {sha: .sha, date: .commit.committer.date, message: (.commit.message | split("\n") | .[0]), author: .commit.author.name}]'

Also fetch the changed files for each commit to classify relevance:

gh api "repos/jahala/tilth/commits?per_page=30&sha=main" --jq '[.[].sha]' | jq -r '.[]' | head -30 | while read sha; do gh api "repos/jahala/tilth/commits/$sha" --jq '{sha: .sha, files: [.files[].filename]}'; done

Subsequent Runs (marker file exists)

Use the compare API:

gh api "repos/jahala/tilth/compare/{LAST_SHA}...main" --jq '{total_commits: .total_commits, commits: [.commits[] | {sha: .sha, date: .commit.committer.date, message: (.commit.message | split("\n") | .[0]), author: .commit.author.name}], files: [.files[].filename]}'

Fallback: If the compare API returns 404 (e.g. force-push rewrote history), fall back to date-based query:

gh api "repos/jahala/tilth/commits?since={LAST_DATE}&sha=main&per_page=100" --jq '[.[] | {sha: .sha, date: .commit.committer.date, message: (.commit.message | split("\n") | .[0]), author: .commit.author.name}]'

Step 3: Classify Changed Files by Relevance

Use these mappings to assign HIGH / MEDIUM / LOW relevance to each changed file:

Relevance	Path Patterns
HIGH	src/**/*.rs (all Rust source — direct counterparts in glean)
MEDIUM	Cargo.toml, Cargo.lock, benchmark/**, flake.nix
LOW	.github/**, README.md, AGENTS.md, LICENSE, scripts/**

Files not matching any pattern -> MEDIUM (unknown = worth reviewing).

Step 4: Present Summary

Format the output as follows:

# Upstream Changes

## jahala/tilth (N new commits since YYYY-MM-DD)

### Commits
- `abc1234` Fix tree-sitter parsing for Go — @author (2025-05-01)
- `def5678` Add support for Zig language — @author (2025-04-28)

### Changed Files

**HIGH relevance** (Rust source — direct counterparts in glean):
- src/search/symbol.rs
- src/read/mod.rs

**MEDIUM relevance** (may affect behavior):
- Cargo.toml

**LOW relevance** (infrastructure/docs):
- README.md

### Assessment
2 high-relevance changes to Rust source — worth reviewing for potential incorporation.

If there are no new commits, show:

## jahala/tilth — No new commits since last check (YYYY-MM-DD)

Step 5: Update Marker File

Build the new marker JSON with the HEAD SHA and current date.

• First run: Write the marker file automatically (tell the user it was created).
• Subsequent runs: Ask the user "Update the last-checked marker to current HEAD?" before writing.

Write to .claude/skills/upstream/references/last-checked.json:

{
  "jahala/tilth": {
    "last_checked_sha": "<HEAD_SHA>",
    "last_checked_date": "<ISO_DATE>"
  }
}