fix(code-review): resolve PR base host-agnostically (GitHub Enterprise fork fix)

[davidalee]

Summary

The stable ce-code-review skill silently picks the wrong merge base — or no base at all — on GitHub Enterprise or any non-github.com host when the reviewer is working from a fork. The base-resolution awk block in SKILL.md matches remotes by literal github.com: / github.com/ substring, and the HTTPS fallback URL is hard-coded to https://github.com/.... On GHE, PR_BASE_REMOTE ends up empty, the script falls through to origin, and in fork workflows origin is the user's fork — so the resulting diff is either empty, incorrect, or relative to the wrong base.

This PR makes base resolution host-agnostic: the agent derives both <base-host> and <base-repo> from the same PR URL it already parses, and the awk block extracts (host, owner/repo) from each remote URL generically. No behavior change for github.com users.

How this was uncovered

While building ce-code-review-beta in #784 (Codex CLI delegation), the Codex code-review bot flagged the identical hard-coding pattern in the beta variant's resolve-base.sh:

The PR-base detection is hard-coded to https://github.com/... and later remote matching is hard-coded to github.com: / github.com/, so reviews on GitHub Enterprise (or any non-github.com host) will fail to identify the true base remote. In fork setups this can silently fall back to origin, producing the wrong merge base (or no base) even when the correct upstream remote exists.

That feedback was resolved in #784. Auditing the stable skill on main confirmed the same root cause — now living inline in SKILL.md after #815 replaced the standalone script with prose-driven base detection. This PR ports the fix.

What changed

plugins/compound-engineering/skills/ce-code-review/SKILL.md — base-resolution prose and awk:

• Prose: instructs the agent to derive both <base-host> and <base-repo> from the PR URL (previously only the repo portion). Calls out case-insensitivity and shows a GHE example alongside the existing github.com example.
• awk: replaces the two index($2, "github.com:<base-repo>") || index($2, "github.com/<base-repo>") substring checks with a per-remote parser that handles:
  • https://[user@]host[:port]/owner/repo[.git]
  • ssh://[user@]host[:port]/owner/repo[.git]
  • scp-form user@host:owner/repo[.git]
  • Strips userinfo, port, and trailing .git; lowercases host and owner/repo before exact-equality comparison.
• HTTPS fallback URL: https://github.com/<base-repo>.git → https://<base-host>/<base-repo>.git.

Why this is safe to merge

• No new dependencies, no new scripts: the change stays inline per fix(ce-code-review): replace resolve-base.sh with prose-driven base detection #815's design intent (prose-driven base detection).
• No behavior change on github.com: the new awk produces the same remote pick for canonical github.com URLs, verified across HTTPS, scp-form, mixed-case, userinfo, port, and .git/no-.git variants.
• Boundary case preserved: org/repo PR does not spuriously match a remote at org/repo-extra (exact equality, not substring).
• No test regressions: full bun test suite passes (1340/1340); bun run release:validate clean.
• Diff is small: 1 file, +15/-4 lines.

Test plan

• bun test — all 1340 tests pass on this branch
• bun run release:validate — metadata in sync
• Awk smoke test with realistic remote URL forms:
  • git@ghe.acme.com:EveryInc/compound-engineering-plugin.git matches (ghe.acme.com, everyinc/compound-engineering-plugin) ✓
  • https://x-token@ghe.acme.com/Org/Repo.git matches (ghe.acme.com, org/repo) ✓
  • git@github.com:org/repo-extra.git does not match (github.com, org/repo) ✓
  • git@github.com:org/repo.git still matches (github.com, org/repo) ✓ (regression guard)

Related

• Upstream feedback that surfaced this: Codex review on #784
• Fix in beta variant: davidalee/compound-engineering-plugin@c09b90d7 (part of PR feat(code-review-beta): code review delegation to Codex #784)
• Prior design context: fix(ce-code-review): replace resolve-base.sh with prose-driven base detection #815 (replaced the standalone resolve-base.sh with inline prose)

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