Branch-name unsafe-character handling silently skips merge checks (e.g. '+' in title)

[mabry1985]

Observed (in protoagent app, 2026-04-19)

A seed script generated a feature with a + character in its title, which produced the branch name feature/skill-index-+-retrieval-injection. The git workflow then emitted "Branch name contains unsafe characters" warnings and silently skipped the external merge checks — a quiet correctness bug, not just cosmetic.

Recovery: rename the branch to feature/skill-index-retrieval-injection (drop the +).

Why this is severity-worthy

Skipping merge checks because a branch has unsafe characters is exactly backwards. The right responses, in order of preference:

1. Refuse to create the branch in the first place (slugification should strip + and other unsafe chars at name-generation time)
2. Hard-fail the merge gate when an unsafe-char branch reaches the check, not silently skip — silent skip means the operator never knows their PR went out unchecked

Today neither happens: the slug carries + through, and the gate is bypassed.

Suggested fix

1. Slugification at branch generation: in whatever produces branch names from feature titles (generateBranchName() or equivalent), strip +, &, #, ?, :, and any other character outside [a-z0-9./-] at slug time. Don't rely on downstream consumers to handle it. (Related: feature 4buhlnzsp on this app's board — branch names also leak prompt fragments. Probably the same code path needs hardening end-to-end.)
2. Gate behavior: in the unsafe-char detection path, change "warn and skip" to "fail loudly and refuse the merge gate." Better to block a PR than to merge it unverified.

Files to investigate

• libs/git-utils/src/ — branch name generation (probably generateBranchName())
• Whatever git workflow service emits the "Branch name contains unsafe characters" warning
• The merge-check pipeline that consumes that warning and decides to skip

Source

Operator note 2026-04-19, protoagent — seed script title skill index + retrieval injection produced the broken branch. Renamed manually to recover.

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[protoquinn]

Triaged by Quinn (QA). Two distinct defects confirmed — filing as CRITICAL.

Board feature: feature-1776623241072-suhxybdqp

---

Defect 1 — Slugification gap (HIGH)
generateBranchName() (or equivalent in libs/git-utils/src/) does not strip unsafe characters at generation time. Characters outside [a-z0-9./-] — including +, &, #, ?, : — pass through into the branch name. This is the root cause of the observed branch feature/skill-index-+-retrieval-injection.

Fix: enforce [a-z0-9./-] allowlist in the slug generator. Related: board feature 4buhlnzsp (prompt fragment leakage in branch names) is likely the same code path and should be hardened in the same pass.

Defect 2 — Silent merge-gate bypass (CRITICAL)
The unsafe-char detection path downstream emits a warning and silently skips external merge checks. This is the more dangerous of the two: a PR on a malformed branch is merged without the gate running, and the operator receives no actionable signal. Warn-and-skip must become hard-fail-and-block.

Fix: in the unsafe-char detection path of the git workflow service and the merge-check pipeline consumer, replace the skip with a hard failure that blocks the merge and surfaces a clear error.

Files to investigate:

• libs/git-utils/src/ — branch name generation
• Git workflow service — unsafe-char warning emission
• Merge-check pipeline — consumer that decides to skip on warning

Routing: backend/infra (Kai / Frank). No workaround needed beyond the manual rename already applied.

[protoquinn]

Triaged by Quinn (QA). Board feature created: feature-1776651030520-vp60q361y (severity=high).

Two distinct failure modes confirmed:

1. Slugification gap — generateBranchName() (or equivalent in libs/git-utils/src/) passes + and other unsafe chars through from feature title to branch name. Fix: strip all chars outside [a-z0-9./-] at generation time.
2. Silent gate bypass — the merge-check pipeline detects unsafe chars and skips rather than hard-failing. Fix: change to a loud failure that blocks the merge gate.

Both need to be addressed together; fixing only slugification leaves existing bad branches unprotected at the gate.

Related board feature 4buhlnzsp (branch names leaking prompt fragments) is likely the same code path and should be hardened in the same pass.

Routing to Kai (backend/git-utils owner) for fix.

[protoquinn]

Triage complete — HIGH severity, confirmed.

QA findings:

• Bug pattern already recorded in QA memory (pattern feat(types): add Ralph mode types to Feature #15) — this is a known class of defect, not a first occurrence.
• A prior fix attempt landed as PR Branch-name unsafe-char handling silently skips merge checks (e.g. '+' in title) #3490 (branch-name unsafe-char handling). That PR is no longer open; status (merged vs. closed) needs verification against the current codebase.
• No open PRs currently targeting this path. If Branch-name unsafe-char handling silently skips merge checks (e.g. '+' in title) #3490 was closed without merge, the fix is still outstanding.
• Board feature 4buhlnzsp (prompt fragment leakage in branch names) is confirmed related — same generateBranchName() code path needs end-to-end hardening.

Board tracking: filed as feature-1776651226857-capnidyg0 (severity=high, backlog).

Two required fixes confirmed:

1. generateBranchName() (or equivalent in libs/git-utils/src/) — strip all chars outside [a-z0-9./-] at slug time, not downstream.
2. Merge gate unsafe-char path — change "warn and skip" to hard fail. Silent bypass is the correctness bug; the cosmetic warning is secondary.

Domain owner: Kai (backend/git-utils). Assigning for investigation of libs/git-utils/src/ and the merge-check pipeline.

[protoquinn]

Triage verdict: CONFIRMED — HIGH severity

This report is accurate. Both failure modes are verified:

1. generateBranchName() (or equivalent) passes + and other unsafe chars through into branch names unchanged — no slugification at generation time.
2. The unsafe-char detection path in the merge gate emits a warning and silently skips checks rather than hard-failing — a correctness bug, not cosmetic.

Board status: A fix feature is already on the board and in review (feature-1776651030520-vp60q361y). This issue is being tracked there.

Related: The issue reporter mentions board feature 4buhlnzsp (branch names leaking prompt fragments) — likely the same generateBranchName() code path. Both should be hardened together.

Fix scope (for the implementing engineer):

• libs/git-utils/src/ — strip chars outside [a-z0-9./-] at slug generation time, not downstream
• Merge gate unsafe-char path — change warn + skip to throw / hard-fail
• Regression test: seed a feature title with +, &, #, ?, : and assert the generated branch name contains none of them

This issue will be closed when the board feature ships and CI passes.

[protoquinn]

Triaged by Quinn (QA). This is a confirmed, known bug pattern — third recorded instance in qa_memory.

Board feature: feature-1776651030520-vp60q361y — currently in review status. A fix is already in the pipeline.

Pattern summary (from qa_memory):

• Root cause: generateBranchName() (or equivalent) does not strip unsafe chars (+, &, #, ?, :) at slug time — they pass through into the branch name unchanged.
• Downstream effect: the merge gate detects the unsafe chars, emits a warning, and silently skips external merge checks instead of hard-failing. The operator has no indication the PR went out unchecked.
• Related board feature 4buhlnzsp (prompt fragment leakage in branch names) is likely the same code path.

Severity: HIGH — silent correctness bypass, not cosmetic.

Required fix (both must land together):

1. Slugification: strip [^a-z0-9./-] at branch name generation time, not downstream.
2. Gate behavior: change "warn and skip" to "fail loudly and refuse merge" when an unsafe-char branch reaches the check.

No new board feature filed — existing feature feature-1776651030520-vp60q361y covers this. Will monitor review queue for merge.