Fix Verify Loop

Fix-Verify Loop

fix-verify-loop is a bounded resolver. Input: confirmed P0/P1 findings. Output: staged code where each listed finding is resolved, OR an escalation list of findings it could not resolve in 2 attempts.

It verifies ONLY per-finding resolution. Regression detection, finding new issues, and reviewing the diff as a whole are explicitly NOT its job — those belong to whoever reviews the diff next (caller's choice).

When to use

After a two-pass-review (or any review) produces confirmed P0/P1 findings that need fixing. Also after test failures that need code or test fixes.

Protocol

Input

• Findings: confirmed P0/P1 findings conforming to the [Output Schema](#output-schema) below
• Artifact paths: files to fix
• Criteria: the original criteria the fix must satisfy

Intake filter: Only process findings where verdict = "confirmed" and severity in ["P0", "P1"]. Ignore P2/P3 findings — they are out of scope. Note: findings with verdict: "confirmed" are accepted regardless of source — the caller is responsible for confirmation quality (e.g., an orchestrator may set this as an escape hatch for review findings that have no verifier pass).

Pre-gate (findings without an independent verifier pass): A finding requires a verifier pre-gate BEFORE Round 1 if it has not been verifier-validated. Detect via:

• evidence field is null or missing, OR
• evidence field starts with "Orchestrator-confirmed".

Confidence is the reviewer or verifier's honest signal — it does not by itself trigger pre-gate. Pre-gate's job is to catch findings that haven't been independently verified, not findings that the verifier already vouched for at low confidence.

For these findings, run this pre-gate first:

1. Spawn the verifier agent with: Artifact = the finding's file (or surrounding context), Findings = the single finding, Criteria = "is this finding real?".
2. If verifier returns rejected → adds to dropped bucket → drop the finding from fix-verify-loop. Skip to next finding.
3. If verifier returns confirmed or demoted (still real) → proceed to Round 1 normally.
4. If verifier output is inconclusive (no parseable verdict) → treat as a failed attempt. Proceed to Round 1 anyway (this consumes one of the two attempts; see inconclusive rule below).

Findings that pass the intake filter and either don't trigger the pre-gate or pass it proceed to Round 1.

Per-finding loop

Process findings sequentially, one at a time. Do not batch. For each finding, run Round 1; if not resolved, run Round 2; if still not resolved, escalate. Round 1 and Round 2 mirror each other in shape — same fix-then-verify dispatch, same verifier question.

Preconditions — pre-staged hunk check

This check fires in Round 1 only, AFTER the fix subagent declares files_changed and BEFORE staging. The fix subagent doesn't know what files it will touch until it runs, so the Round 1 order is: spawn fix → check pre-staged hunks → stage → verify. In Round 2, any pre-existing staged content is from Round 1's prior attempt and not user-authored — the check would fire spuriously, so we skip it. Round 2 order is: spawn fix → stage → verify.

Before staging (Round 1 only):

• Run git diff --staged -- (the files_changed returned by the fix subagent).
• If non-empty (pre-existing staged hunks exist in those files):
• Inspect the hunks. Form a heuristic judgment:
• No overlap with the fix's likely lines, hunks small, look unrelated → recommend "Commit pre-existing first"
• Overlap with the fix's lines, OR hunks large/sprawling → recommend "Stash pre-existing"
• Hunks clearly continue the fix's logical change → recommend "Proceed (treat as part of this fix)"
• Use the AskUserQuestion tool with options "Commit pre-existing first", "Stash pre-existing", "Proceed (treat as part of this fix)". Include a one-line summary of what was found (e.g., "3 hunks in auth.js totaling 18 lines, no overlap with fix's edits"). Surface the heuristic recommendation as the first option labeled "(Recommended)".

Round 1 — Fix + Verify

1. Fix. Spawn a fix subagent (Opus). Subagent receives: the finding (full schema), the affected file path(s), the criterion it violates. Subagent edits the working tree and returns { files_changed: [paths], summary: string, concerns: [string] | null }.
2. Pre-staging check. Run the [Preconditions](#preconditions--pre-staged-hunk-check) check on files_changed.
3. Stage. git add — do NOT commit. The user decides when to commit.
4. Verify. Spawn the verifier agent with:

• Artifact: the staged diff scoped to this finding's files (git diff --staged -- )
• Findings: the original finding being fixed (single)
• Criteria: ONLY "is this finding resolved?"
• Output contract: "Return a ReviewOutput envelope (see [Output Schema](#output-schema)) with a verdict on the single finding."

1. Decide. Map the verifier's verdict on the finding:

• confirmed → still real and still in scope (P0/P1) → not resolved → proceed to Round 2.
• rejected → not a real issue → adds to resolved bucket → done.
• demoted → check the new severity:
• new severity in [P0, P1] → still in fix-verify-loop scope → proceed to Round 2.
• new severity in [P2, P3] → out of fix-verify-loop scope → adds to demoted bucket → done (the issue exists at lower severity; hand-off implicit).
• Inconclusive (the verifier subagent fails to return a parseable ReviewOutput — crash, malformed output, no verdict on the finding) → counts as a failed attempt. Proceed to Round 2. No retry loop.

Round 2 — Fix + Verify

Same shape as Round 1. The only difference is the fix subagent gets Round 1 context.

1. Fix. Spawn another fix subagent with full Round 1 context (what was attempted, why it didn't work, the verifier's evidence). Subagent returns { files_changed: [paths], summary: string, concerns: [string] | null }.
2. Stage. git add . (No pre-staging check in Round 2 — see [Preconditions](#preconditions--pre-staged-hunk-check) for why.)
3. Verify. Same dispatch as Round 1 — verifier asked "is this finding resolved?" on the single finding.
4. Decide. Map the verifier's verdict on the finding:

• confirmed → still real and still in scope (P0/P1) → not resolved → adds to escalated bucket → escalate (do not attempt Round 3).
• rejected → not a real issue → adds to resolved bucket → done.
• demoted → check the new severity:
• new severity in [P0, P1] → still in fix-verify-loop scope → adds to escalated bucket → escalate.
• new severity in [P2, P3] → out of fix-verify-loop scope → adds to demoted bucket → done (the issue exists at lower severity; hand-off implicit).
• Inconclusive (the verifier subagent fails to return a parseable ReviewOutput) → counts as a failed attempt → adds to escalated bucket → escalate. No retry loop.

Escalation

If Round 2 still has the finding unresolved:

• STOP. Do not attempt Round 3.
• Present to the user in this shape (derive the staged line via git diff --staged --stat -- ):

``` Escalated — finding not resolved after 2 attempts:

• Finding: [ID — title]
• Attempted: [Round 1 summary] → [Round 2 summary]
• Still unresolved: [verifier's evidence | verifier inconclusive]
• Currently staged: [e.g. "R2's changes to auth.js, +12/-4 lines" | nothing staged]

`` Then use the AskUserQuestion` tool with options: "Manual fix", "Try a different approach", "Defer this finding", "Discard R2 changes and revert". Recommended: "Defer this finding".

After all findings are processed, return a [FixVerifyLoopOutput](#fixverifyloopoutput) envelope with four buckets:

• resolved: finding IDs marked done in Round 1 or Round 2 (with the staged files)
• escalated: findings that hit Round 2 without resolution, with attempt summaries
• dropped: findings the pre-gate verifier rejected as not-real
• demoted: findings demoted to P2/P3 by the verifier (out of fix-verify-loop scope)

Bucket assignment by verdict path:

• Pre-gate rejected → dropped
• Pre-gate confirmed or demoted → proceed to Round 1
• R1 rejected → resolved
• R1 confirmed (still real, P0/P1) → proceed to Round 2
• R1 demoted to [P0, P1] → proceed to Round 2
• R1 demoted to [P2, P3] → demoted
• R2 rejected → resolved
• R2 confirmed (still real, P0/P1) → escalated
• R2 demoted to [P0, P1] → escalated
• R2 demoted to [P2, P3] → demoted

Rules

• Max 2 attempts. Never loop beyond Round 2.
• Scoped fixes. Fix subagents must NOT edit files outside the scope of their finding without user approval. If a fix requires additional files, the subagent must FIRST return { needs_scope_expansion: true, additional_files: [paths], justification: string } instead of making edits. The parent then uses the AskUserQuestion tool with options: "Approve expanded scope", "Reject — fix within original scope only", "Defer this finding". Recommended: "Approve expanded scope" (include the justification and file list). On approval, re-dispatch the subagent with expanded scope. Additional files are included in verification.
• Always verify. Every fix gets the verifier-on-one-question check. Don't skip — the verifier agent is the only verification mechanism this skill uses.
• Test failures. Determine if it's a code bug or test bug first, then fix the right one. This judgment happens during the fix subagent's work — the subagent inspects the failure and the test, decides which is wrong, and fixes the right one. The skill itself does not branch on this; it's part of the fix subagent's task.

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Output Schema

FixVerifyLoopOutput

The skill returns this envelope after all findings are processed:

{
  resolved: [Finding.id, ...],            // fixed in R1 or R2
  escalated: [{                           // could not be fixed in 2 attempts
    id: Finding.id,
    attempts: [string, string],           // R1 + R2 summaries
    evidence: string | null,              // verifier's evidence (null if R2 was inconclusive)
    staged_summary: string                // e.g., "R2's changes to auth.js, +12/-4 lines"
  }, ...],
  dropped: [{                             // pre-gate verifier rejected as not-real
    id: Finding.id,
    reason: string                        // verifier's rejection evidence
  }, ...],
  demoted: [{                             // demoted to P2/P3 (out of scope)
    id: Finding.id,
    new_severity: "P2" | "P3",
    evidence: string                      // verifier's demotion reasoning
  }, ...]
}

Finding

Finding {
  id: sequential number starting from 1,
  severity: "P0" | "P1" | "P2" | "P3",
  title: short title,
  body: detailed explanation with evidence,
  file: file path or null for global issues,
  line_start: number or null,
  line_end: number or null,
  confidence: 0.0-1.0,
  criterion: what was violated,
  verdict: "confirmed" | "demoted" | "rejected" | null,
  evidence: reasoning for verdict | null
}

ReviewOutput

Findings are wrapped in a ReviewOutput envelope:

ReviewOutput {
  schema_version: "v1",
  findings: Finding[],
  checks_run: string[]
}

Severity calibration

• P0 — Must fix: breaks functionality, security breach, data loss, or violates criteria
• P1 — Fix before shipping: correct but incomplete, fragile, or reliability risk
• P2 — Should fix: quality issue, code smell, not blocking
• P3 — Nice to have: observation, style, minor improvement

Field notes

• confidence — 1.0 means certain, below 0.5 means you're guessing. Be honest.
• criterion — required for P0/P1 findings. Name the specific criterion violated.
• verdict — populated by the verifier in two-pass review. Set to null when producing findings directly.
• evidence — verifier's reasoning for the verdict. Set to null when producing findings directly.
• checks_run — list every criterion evaluated, file path checked, or acceptance criterion verified. For ACs, use AC-N: PASS — [evidence] or AC-N: FAIL — [reason].

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: preetamnath
• Source: preetamnath/agent-skills
• License: MIT
• Homepage: https://www.preetamnath.com/blog/agent-skills

Install and usage instructions live in the source repository linked above.