google/mantis-review
>- Independently reviews findings and filters out false positives. Use when consolidated findings need validation against the actual source code. Don't use for reproducing crashes or patching code.
npx skills add https://github.com/google/mantis --skill mantis-review
Independent Validator. Reviews consolidated findings against active source code
to verify validity and filter out noise and false positives.
/mantis-reviewpositives.
workspace/findings/ (finding JSON files, including each finding's optionaldiscovery_commit provenance stamp).
workspace/.mantis_state.json (current loop pass_number; and, whenpresent, active_snapshot = {root, snapshot_id, snapshot_pinned} for
snapshot provenance).
--snapshot_root,--snapshot_id, --state_root (and, rarely, --target_root).
code_paths paths/lines, read under theresolved CODE_ROOT (the pinned snapshot root — see Instructions Step 0 /
Block A), never the live tree when a snapshot is pinned.
"status", "reasoning","repro_hints", "triage_checklist", and appends history).
workspace/helpers/append_review.py.workspace/findings/ exists with finding files.append_review.py,which MUST carry # MANTIS_HELPER_VERSION = 2 as its first line; regenerate
the helper if that marker is absent or a different integer (see Instructions
step 5).
finding, scan its history array:
--snapshot_id was passed NOR isactive_snapshot readable in state): SKIP the review update iff a
"stage": "reviewer" entry already exists for the current pass_number
(byte-for-byte today's behavior).
"stage": "reviewer"entry exists whose pass_number equals the current pass AND whose
snapshot equals SNAPSHOT_ID. A reviewer entry that lacks snapshot
(legacy) or carries a different snapshot counts as UNKNOWN → RE-REVIEW
(do NOT skip), so a finding reviewed under the old skill is re-grounded
against the current pinned snapshot.
Read and evaluate the deduplicated findings against the actual source code of
the repository. **Assume every finding is a false positive by default. Your job
is to disprove the finding using an adversarial stance. Evaluate the claim based
ONLY on the code and the raw claim itself. Explicitly ignore the original
finder's prose reasoning and justification, as they may be hallucinated.**
Execute your validation as follows:
**Step 0 — Locator Resolution & Snapshot Provenance Gate (do this FIRST, before
reading any finding's code):**
0a. Resolve where to read code. Block A — Locator Resolution here:
LOCATOR RESOLUTION (before reading ANY target code or artifact):
0. ROLE: If this skill NEVER reads target source (report, calibrate, reflect),
you are a FINDINGS-ONLY stage: skip steps 2-6; still read active_snapshot from
state for provenance/annotation; NEVER stop merely because a code root is unset.
1. Determine CODE_ROOT, in this priority order:
a. If --target_root is passed on THIS invocation, CODE_ROOT = --target_root.
It is AUTHORITATIVE and OVERRIDES SNAPSHOT_ROOT and the state fallback
(used when a caller hands you a prepared tree, e.g. a patched shadow).
b. Else if --snapshot_root (or SNAPSHOT_ROOT) is passed, use it.
c. Else read state_root/workspace/.mantis_state.json (state_root from
--state_root if passed, else ./workspace/... relative to the current dir)
-> active_snapshot.root / .snapshot_id / .snapshot_pinned.
d. Else (no arg AND no readable active_snapshot): CODE_ROOT = current directory,
treat snapshot_pinned = false (MODE-OFF). Do NOT stop.
2. SENTINEL CHECK (only if snapshot_pinned is true AND you did NOT take path 1a):
verify CODE_ROOT/.mantis_snapshot_id exists and equals SNAPSHOT_ID. If missing
or different -> STOP "snapshot sentinel mismatch". (A --target_root tree (1a) is
deliberately mutated and is sentinel-EXEMPT.)
3. PATH FIELDS:
- SNAPSHOT-RELATIVE (read under CODE_ROOT): code_paths entries; plan target_files
that are file paths. Strip ONLY a trailing ":<digits>". A code_paths entry
containing "://" is a URL/endpoint, NOT a file read. A code_paths entry that is
NOT of the form <existing-path>:<integer> is a non-source LOCATOR
(symbol/offset/endpoint): only check that the artifact/symbol exists; skip ALL
line-range and line-existence logic.
- STATE-RELATIVE (read/write under state_root/workspace, NEVER prefix CODE_ROOT):
kb_references, repro_file_path, reattack_file_path, helper scripts, report
files, and all state/findings JSON.
4. Never WRITE under CODE_ROOT when snapshot_pinned is true. Any command that
compiles, generates, or writes artifacts MUST run in a PRIVATE SHADOW copy
(mktemp -d from CODE_ROOT), never with cwd=CODE_ROOT. Read-only inspection may
cd into CODE_ROOT.
5. VCS-METADATA CARVE-OUT: history-log extraction and any VCS diff/blame command
run in the LIVE repository root (which still has .git/.hg/.repo), NOT CODE_ROOT
(the snapshot copy strips VCS metadata). Do NOT stop merely because CODE_ROOT
lacks .git/.hg/.repo.
6. Every shell command uses ABSOLUTE paths and sets its own working directory on
that call. Do NOT assume the working directory persists between calls.
The reviewer READS target source, so it is NOT a findings-only stage: run all of
Block A steps 1-6. CODE_ROOT is the pinned snapshot root you will read every
code_paths entry under. Per Block A step 3, a code_paths entry containing
:// is a URL (existence check only), and any entry not of the form
<existing-path>:<integer> is a non-source locator (check the artifact/symbol
exists; skip all line-existence logic). Never STOP merely because CODE_ROOT
lacks .git/.hg (Block A step 5).
> [!NOTE] **CURRENT-PASS CHECK (defensive; the binding guarantee is on the
> harness per mantis-pipeline-adapter Scenario 2):** if active_snapshot is
> present AND active_snapshot.pass != state.pass_number, treat the snapshot as
> STALE for this pass — STOP "stale active_snapshot: pass mismatch" or degrade
> as HALT (snapshot_pinned effectively false: no authoritative verdicts, Block
> B NOT_MATCHED, reproduce not_attempted). This catches a custom harness that
> preserved active_snapshot across the Stage 15 pass increment without
> re-pinning. The reference meta-agent re-pins every pass, so this check never
> fires there. Block B itself cannot detect this (it is snapshot_id-only, not
> pass-aware).
0b. Determine SNAPSHOT MODE (once, before touching findings): - SNAPSHOT
MODE is OFF iff --snapshot_id was NOT passed on this invocation AND
workspace/.mantis_state.json has no readable active_snapshot. This is a
legacy / non-sync run: do NOT run the Snapshot Provenance Gate below; review
EVERY finding with steps 1-5 exactly as before. - Otherwise SNAPSHOT MODE is
ON. From Block A you now hold SNAPSHOT_ID and snapshot_pinned. Apply the
Snapshot Provenance Gate (0c) to every finding.
0c. Snapshot Provenance Gate (SNAPSHOT MODE ON only). After Step 1 loads the
findings, apply the match check to EACH finding F via **Block B — Snapshot Match
Check**, applied to F:
SNAPSHOT MATCH CHECK for finding F (decides MATCHED vs NOT_MATCHED):
1. If snapshot_pinned is false -> NOT_MATCHED. Stop.
2. Read F.discovery_commit:
- missing OR empty OR the literal "MIXED" -> NOT_MATCHED.
- not exactly equal to SNAPSHOT_ID -> NOT_MATCHED.
- exactly equal to SNAPSHOT_ID -> MATCHED.
There is no other route to MATCHED; never fuzzy-compare. The global "default the
field and proceed" backward-compat rule does NOT apply to discovery_commit:
absent = NOT_MATCHED. (There is NO separate "dirty" gate: a dirty tree's
SNAPSHOT_ID already embeds the working-tree content hash, so within-pass findings
MATCH and cross-pass bare-commit findings do not.)
Then, using the idempotency rule (Input/Output Contract → Idempotency Guarantee)
to avoid double-writes:
2-5 (the full 13-rule review) for F.
snapshot_pinned false / HALT / live-endpointpass; discovery_commit missing, empty, or the literal MIXED; or
discovery_commit != SNAPSHOT_ID) → F was discovered against a different (or
absent/unpinned) snapshot; its code_paths line numbers may no longer point
at the same code. **DO NOT run the 13 rules on F. DO NOT mark it
FALSE_POSITIVE.** Finalize F as a drift NEEDS_RESEARCH via the helper (step
5), writing EXACTLY:
"status": "NEEDS_RESEARCH""reasoning":"Snapshot drift: finding discovered against snapshot <F.discovery_commit or 'unknown'>, which does not match the current pinned snapshot <SNAPSHOT_ID>. Not re-validated this pass; routed to re-research."
"repro_hints" (and, if F carried stale repro_hints from a priorpass, leave them — they are ignored downstream because status is not
VALID/PROVISIONALLY_VALID).
"triage_checklist": all 13 constraints set to UNKNOWN (paste the objectbelow verbatim). This object is REQUIRED: appending a reviewer history
entry makes triage_checklist mandatory on a non-chain finding
(schema.json lines 365-398), and for a NEEDS_RESEARCH finding every
entry MUST avoid FAIL/passes:false (schema.json lines 418-470).
Setting ensure_source_code_coherence and
verify_attacker_control_of_source to UNKNOWN (never FAIL) is the whole
point: a line/path mismatch caused by DRIFT is NOT evidence of
hallucination, so Rules 12/13 must NOT fire on it.
reviewer "history" entry (with "snapshot", per step 5 / thehistory JSON below). Then STOP processing F — skip steps 2-5 for it.
Drift triage_checklist (paste verbatim; all 13 keys, all UNKNOWN):
{
"ignore_hypothetical_misuse": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"ignore_missing_hygiene": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"require_strict_reproducibility": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"avoid_pedantic_linting": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"no_security_flaw_stretching": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"evaluate_questionable_file_paths": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"ignore_resource_exhaustion_dos": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"intrinsic_security_flaws": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"verify_mitigations_pragmatically": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"refine_code_paths_strictly": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"ignore_simd_vector_padding": { "outcome": "UNKNOWN", "reason": "snapshot drift: not re-validated against the current pinned snapshot" },
"ensure_source_code_coherence": { "outcome": "UNKNOWN", "reason": "snapshot drift: line/path mismatch may be caused by drift, not hallucination; not re-validated" },
"verify_attacker_control_of_source": { "outcome": "UNKNOWN", "reason": "snapshot drift: trust-boundary path not re-traced against the current pinned snapshot" }
}
Findings finalized as drift NEEDS_RESEARCH in Step 0c are DONE — do not
process them again in steps 2-5. Only MATCHED findings (SNAPSHOT MODE ON) or all
findings (SNAPSHOT MODE OFF) flow into steps 2-5 below.
workspace/findings/directory. If the directory is empty or missing, notify the user.
SNAPSHOT MODE ON, only findings that were MATCHED in Step 0c; findings
finalized there as drift NEEDS_RESEARCH are already done and are skipped),
read the file under CODE_ROOT (the pinned snapshot root resolved in
Step 0 / Block A — resolve every code_paths path relative to CODE_ROOT,
never the live tree) to inspect the exact files and line numbers listed in
code_paths and confirm the finding is grounded in the actual snapshot
state. Do not make assumptions about the validity of a path without
inspecting the source code first.
each finding against these strict criteria. Mark a finding as
FALSE_POSITIVE if it violates any of the following rules:
01. Ignore Hypothetical Misuse: Do not flag security flaws that rely on a
calling API hypothetically misusing a function, writing bad fallback
logic, or sending invalid parameters if the function itself behaves
safely.
02. Ignore Missing Hygiene / Defense-In-Depth: Do not report missing HTTP
security headers (e.g., X-Content-Type-Options), missing authentication
on local-only test functions, or hardcoded mock databases as security
flaws.
03. Require Strict Reproducibility: Only mark a finding as VALID if a
direct, unambiguous, and triggerable flaw exists within the boundaries of
the code logic. If the finding is extremely fragile (e.g., relies on
unstable timing that cannot be automated or brute-forced, or requires
unrealistic environmental conditions to trigger), mark it as
FALSE_POSITIVE. *Note on Race Conditions:* Do NOT dismiss race conditions
or timing bugs simply because they have a low success probability (e.g.,
1 in a million), provided the attack path can be automated and repeatedly
attempted by an attacker to eventually trigger the exploit.
04. Avoid Pedantic Linting: If the code uses standard safe libraries
(such as json.loads, parameterised SQL queries, or secure standard
library hashes) but lacks extreme paranoia, mark it as FALSE_POSITIVE.
05. No Security Flaw Stretching on Mitigations: If you are reviewing a
mitigation or a safe variant of a function that successfully blocks the
original security flaw class, do NOT invent complex protocol-level
bypasses or adjacent security flaw classes (e.g., SSRF when reviewing
Command Injection fixes). If the primary security flaw is successfully
blocked, mark it as FALSE_POSITIVE.
06. Evaluate Questionable File Paths: Do NOT instantly dismiss a finding
simply because its path contains /test, /experimental, or /mock.
Code in these paths is sometimes compiled into production targets or
reachable via production endpoints. Do not blindly assume it is safe;
instead, take reasonable measures to trace its usage to confirm whether
it is actually exposed in production.
07. Ignore Resource Exhaustion DoS: Do not flag functions for lacking
recursion limits, input size boundaries, or cycle constraints unless the
primary stated purpose of the module is to defend against DoS attacks.
08. Intrinsic Security Flaws: If a function uses a fundamentally broken
algorithm (such as MD5, SHA1), hardcodes static secrets, or contains
direct injection paths in its own logic, mark it as VALID even if it is
not currently called anywhere in the codebase.
09. Verify Mitigations Pragmatically: Do not hallucinate flaws in active
mitigations. If the code adds trailing validation slashes or configures
safe parsing flags, accept that the mitigation works.
10. Refine code_paths Strictly: The code_paths field should only
include the exact filename:line_number of the flawed code block. Strip
out any helper files, test harnesses, or correct caller files from
code_paths.
11. Ignore SIMD/Vector Padding Violations: If a finding represents an
out-of-bounds read or write inside optimized vector routines (e.g., NEON,
SSE, AVX, VSX), verify if the library employs a global memory allocation
contract (such as trailing safety padding, like row_bytes + 16). If the
out-of-bounds access is mathematically guaranteed to reside entirely
within this pre-allocated padding buffer under all execution paths, mark
the finding as a FALSE_POSITIVE (By Design).
12. Ensure Source Code Coherence (Anti-Hallucination): Verify that every
file path listed in code_paths exists in the repository, and that
function names, variable names, or line numbers actually exist at those
locations. If references are missing or incorrect, immediately mark the
finding as a FALSE_POSITIVE to prevent downstream agents from wasting
resources on hallucinated bugs.
13. Verify Attacker Control of the Source (Trust-Boundary Tracing):
Before marking a data-flow finding VALID, identify and cite the file:line
where untrusted data enters the analyzed codebase (the "Ingress Point")
from which the specific tainted field's value flows to the sink, OR where
that field is populated by an untrusted writer.
multi-component repo), cite the writer.
ingress point on the data-flow path (e.g., reads from shared memory,
IPC handlers, HTTP request parameter retrieval).
origins (server-authored static config, host-plane internal state),
mark FALSE_POSITIVE.
where the vulnerability exists in library code independent of active
callers.
flaw.
uncertain of its feasibility without dynamic verification (e.g. requires
complex heap grooming or precise timing).
complexity, unresolved external APIs, or massive call graphs — OR because
the finding was NOT_MATCHED by the Step 0c Snapshot Provenance Gate
(snapshot drift). Drift findings are finalized in Step 0c and never reach
these 13 rules; do NOT re-classify a drift finding as FALSE_POSITIVE.
FALSE_POSITIVE is the ONLY status for which atriage_checklist entry may be "FAIL" (or "passes": false). For any
VALID, PROVISIONALLY_VALID, or NEEDS_RESEARCH finding, EVERY
checklist entry must be PASS / NOT_APPLICABLE / UNKNOWN — never
FAIL — or schema.json (lines 418-470) will reject the finding. If a
rule looks failed but you are NOT setting status to FALSE_POSITIVE
(e.g. Rule 12/13 references look off only because of snapshot drift), use
UNKNOWN with a reason, not FAIL.
triage_checklist object evaluating all 13 negativeconstraints. For each rule, set outcome to:
"PASS": if the finding satisfies the constraint (does not violate therule, meaning the bug remains potentially valid).
"FAIL": if the finding violates the rule. Setting ANY entry to"FAIL" REQUIRES the finding's status to be FALSE_POSITIVE
(schema.json lines 418-470 reject FAIL on VALID/
PROVISIONALLY_VALID/NEEDS_RESEARCH). A FAIL entry also REQUIRES a
reason (schema.json lines 788-797).
"UNKNOWN": if the rule applicability is unresolved/needs research(REQUIRES a reason). Use this — not "FAIL" — whenever the finding
is not being marked FALSE_POSITIVE, including all rules on a drift
NEEDS_RESEARCH finding (Step 0c).
"NOT_APPLICABLE": if this rule is entirely irrelevant to this classof bug (REQUIRES a reason).
status is VALID, every entry must be PASS orNOT_APPLICABLE (no UNKNOWN, no FAIL) per schema.json lines
471-507.
VALID or PROVISIONALLY_VALID, provide high-signal "repro_hints"
explaining how a reproducer agent can trigger the bug, what inputs or payload
parameters are required, and what crash condition, sanitizer trace
(ASan/UBSan/MSan/TSan), or functional validation result (e.g., an unexpected
HTTP 200 OK) is expected to confirm the security flaw.
re-emit or manually rewrite the entire JSON object in your output.** Instead,
write a reusable helper script (e.g., workspace/helpers/append_review.py)
during your first finding update. For all subsequent findings, do not
regenerate the script; simply execute the existing helper script with the new
parameters to append the required fields.
Helper version guard (mechanical): the helper's FIRST line MUST be the
comment # MANTIS_HELPER_VERSION = 2. Before reusing an existing
workspace/helpers/append_review.py, check that first line (a one-line
grep): if the marker is ABSENT or a DIFFERENT integer, REGENERATE the helper
(an old persisted helper would silently omit the snapshot provenance field
and mishandle the drift path). The regenerated helper MUST:
status, reasoning, optional repro_hints,triage_checklist (JSON), pass_number, timestamp, and snapshot
(write it under key "snapshot", never "snapshot_id");
history entry INCLUDING "snapshot" (the currentSNAPSHOT_ID; omit or write "" only in SNAPSHOT MODE OFF, where no
snapshot is in play);
Guarantee): do nothing if a matching reviewer entry already exists.
You must append the following to the existing object:
"status" field (one of "VALID", "FALSE_POSITIVE","PROVISIONALLY_VALID", or "NEEDS_RESEARCH").
"reasoning" field."repro_hints" field (optional for "NEEDS_RESEARCH" or"FALSE_POSITIVE").
"triage_checklist" object containing evaluations for all 13 negativeconstraints (each key in the object maps to the constraint of the matching
name from Section 3 above):
{
"ignore_hypothetical_misuse": { "outcome": "PASS" },
"ignore_missing_hygiene": { "outcome": "PASS" },
"require_strict_reproducibility": { "outcome": "FAIL", "reason": "Requires unstable 1-in-a-million race condition that cannot be automated." },
"avoid_pedantic_linting": { "outcome": "PASS" },
"no_security_flaw_stretching": { "outcome": "PASS" },
"evaluate_questionable_file_paths": { "outcome": "PASS" },
"ignore_resource_exhaustion_dos": { "outcome": "PASS" },
"intrinsic_security_flaws": { "outcome": "PASS" },
"verify_mitigations_pragmatically": { "outcome": "PASS" },
"refine_code_paths_strictly": { "outcome": "PASS" },
"ignore_simd_vector_padding": { "outcome": "PASS" },
"ensure_source_code_coherence": { "outcome": "PASS" },
"verify_attacker_control_of_source": { "outcome": "PASS" }
}
For backward compatibility, the schema also permits "passes": <bool> as
an alternative to "outcome", but "outcome" is preferred. The reason
must be provided if the outcome is FAIL, UNKNOWN, or NOT_APPLICABLE
(or if passes is false) to explain the evaluation; it should be omitted
for PASS / true to save tokens.
"history" array (now carrying the snapshot the review wasperformed against, for (pass_number, snapshot) idempotency):
{
"stage": "reviewer",
"action": "reviewed",
"details": "Determined status as [VALID/FALSE_POSITIVE/PROVISIONALLY_VALID/NEEDS_RESEARCH] because [reason]",
"pass_number": <current_pass_number>,
"snapshot": "<SNAPSHOT_ID>",
"timestamp": "<current_iso8601_timestamp>"
}
In SNAPSHOT MODE OFF (no snapshot in play), set "snapshot": "" (or omit the
field). schema.json's history_entry has no additionalProperties:false,
so this extra field validates unchanged.
When complete, notify the user.
Take google/mantis-review from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
The agent identifies a skill by the name field in its header. Two skills with the
same name cannot sit side by side — one of them will be ignored.