Bug: git push errors with confusing error message when there's nothing to push when using pre-push qlty hook

[noahd1]

What happened?

[qltysh/cloud (nd-ghm-schema)] $ git push

   ERROR

 > Missing remote commit ID from Git pre-push input
error: failed to push some refs to 'github.com:qltysh/cloud.git'
[qltysh/cloud (nd-ghm-schema)] $ git push --no-verify
Everything up-to-date
[qltysh/cloud (nd-ghm-schema)] $

What did you expect to happen?

I expected to see "Everything up-to-date" without an error message as if the pre-push hook wasn't there

Can you reproduce the problem?

Yes, consistently

CLI Version

qlty 0.556.0 macos-arm64 (9ed3b48 2025-07-17)

[brynary]

@claude please inspect our Git hooks. Diagnose the issue and add a comment here with your findings. Don't make any code changes yet

[claude]

Claude finished @brynary's task —— View job

---

Diagnosis Complete: Pre-Push Hook Bug Analysis

Todo List

• Find Git hooks implementation in codebase
• Examine pre-push hook code
• Identify source of "Missing remote commit ID" error
• Analyze edge case when nothing to push
• Document findings and root cause

---

Root Cause Analysis

Issue Location: qlty-cli/src/commands/check.rs:332

The Problem: The pre-push hook fails when there's nothing to push because it doesn't handle empty Git input gracefully.

Current Flow

1. Git executes .qlty/hooks/pre-push.sh → calls qlty check --upstream-from-pre-push
2. Code reads stdin expecting: <local-ref> SP <local-object-name> SP <remote-ref> SP <remote-object-name> LF
3. When nothing to push, Git sends empty input
4. Code splits empty input → parts.get(3) returns empty string
5. Bug: Code throws error instead of handling empty case gracefully

Current Code Logic (Lines 328-333)

let parts: Vec<&str> = buffer.split_whitespace().collect();
let remote_commit_id = parts.get(3).unwrap_or(&"");

if remote_commit_id.is_empty() {
    bail!("Missing remote commit ID from Git pre-push input")  // ← BUG HERE
}

What Should Happen

When there's nothing to push, the hook should:

• Recognize empty input as a valid "nothing to push" scenario
• Exit successfully (like git push --no-verify does)
• NOT run any checks since there are no changes to analyze

The Fix

The code should handle empty input as a valid case and return early, rather than treating it as an error. When buffer is empty or parts has fewer than 4 elements, it should return Ok(None) instead of bailing.

Missing Test Coverage

• No tests exist for the --upstream-from-pre-push functionality
• No tests for the "nothing to push" edge case
• No integration tests for various Git pre-push scenarios

Recommendation: Handle empty Git input gracefully in the compute_upstream() function and add comprehensive test coverage for pre-push scenarios.