gstack/docs/greptile.md

Greptile Integration

Greptile is a YC company that reviews your PRs automatically. It catches real bugs — race conditions, security issues, things that pass CI and blow up in production. It has genuinely saved my ass more than once. I love these guys.

Setup

Install Greptile on your GitHub repo at greptile.com — it takes about 30 seconds. Once it's reviewing your PRs, gstack picks up its comments automatically. No additional configuration.

How it works

The problem with any automated reviewer is triage. Greptile is good, but not every comment is a real issue. Some are false positives. Some flag things you already fixed three commits ago. Without a triage layer, the comments pile up and you start ignoring them — which defeats the purpose.

gstack solves this. /review and /ship are now Greptile-aware. They read Greptile's comments, classify each one, and take action:

• Valid issues get added to the critical findings and fixed before shipping
• Already-fixed issues get an auto-reply acknowledging the catch
• False positives get pushed back — you confirm, and a reply goes out explaining why it's wrong

The result is a two-layer review: Greptile catches things asynchronously on the PR, then /review and /ship triage those findings as part of the normal workflow. Nothing falls through the cracks.

Learning from history

Every false positive you confirm gets saved to ~/.gstack/greptile-history.md. Future runs auto-skip known FP patterns for your codebase. And /retro tracks Greptile's batting average over time — so you can see whether the signal-to-noise ratio is improving.

Two-tier reply system

• Tier 1 (friendly): First response to a comment. Includes inline diff, explanation, and evidence.
• Tier 2 (firm): When Greptile re-flags the same issue after a prior reply. Full evidence chain + re-rank request.

Every reply includes evidence — inline diffs, code references, suggested severity re-ranking. No vague one-line replies.

Example

You:   /ship

Claude: [syncs main, runs tests, pre-landing review...]

        Greptile found 3 comments on this PR:

        [VALID] app/services/payment_service.rb:47 — Race condition:
        concurrent charges can double-debit. Recommend DB-level advisory
        lock around the charge block.
        → https://github.com/you/app/pull/42#discussion_r123

        [ALREADY FIXED] app/models/user.rb:12 — Missing null check
        on email before downcase.
        → Already fixed in commit abc1234. Auto-replying.

        [FALSE POSITIVE] lib/auth.rb:88 — "Token comparison should
        use constant-time comparison." We already use
        ActiveSupport::SecurityUtils.secure_compare here.
        → https://github.com/you/app/pull/42#discussion_r125

        Fixing the race condition in payment_service.rb...
        Applied advisory lock. Committed: fix: address Greptile
        review — advisory lock on concurrent charges

        The auth token comment is a false positive — we're already
        using secure_compare.

        Options for the false positive:
          A) Reply to Greptile explaining (recommended)
          B) Fix it anyway
          C) Ignore

You:    A

Claude: Replied to Greptile. Re-running tests after the fix...
        All tests pass. Continuing to version bump.

        [creates PR with Greptile Review section in body]
        PR: https://github.com/you/app/pull/42

Three Greptile comments. One real fix. One auto-acknowledged. One false positive pushed back with a reply. Total extra time: about 30 seconds. And the PR body has the full audit trail.