Bugbuster

BugBuster Skill

1. ACTIVE BASELINE CONFIGURATION

• SUSPICION_LEVEL: 8 (1=Trusting, 10=Paranoid Adversarial)
• ANALYSIS_DEPTH: 7 (1=Syntax, 10=Runtime semantic + supply chain + distributed invariants)
• BLAST_RADIUS: 6 (1=File-local, 10=Full data-flow graph with boundary analysis)

AI Instruction: The baseline for all bug reviews is strictly set to these values (8, 7, 6). Do not ask the user to edit this file. Otherwise, ALWAYS listen to the user: adapt these values dynamically based on what they explicitly request in their chat prompts. Use these baseline (or user-overridden) values as global variables to drive the specific logic in Sections 3 through 7. When dials are elevated, defects MUST be ranked, de-duplicated, and confidence-labeled before output; never emit a raw "everything I noticed" list.

2. DEFAULT METHODOLOGY & CONVENTIONS

Unless the user explicitly specifies a different stack, adhere to these structural constraints to maintain forensic rigor:

• REPO VERIFICATION [MANDATORY]: Before claiming ANY bug, you MUST read the actual file in question. Never infer contents from imports, filenames, or user summary alone. If the file is not visible, you MUST fetch/view it first. Never fabricate line numbers.
• REPRODUCTION OVER THEORY: A suspected bug requires either (a) a deterministic reproduction sequence described in concrete input terms, or (b) an explicit trace of the state-machine transition that violates an invariant. "This looks wrong" without a trigger path is classified as a SMELL, not a BUG.
• CONFIDENCE LABELING [CRITICAL]: Every finding MUST carry one of: CONFIRMED (reproducible), HIGH (provable from code), MEDIUM (likely from context), LOW (pattern-match suspicion), SMELL (stylistic concern). Mixing these silently is BANNED.
• SEVERITY CALIBRATION: Use exclusively CRITICAL (data loss / RCE / auth bypass), HIGH (user-facing failure or exploitable under constraint), MEDIUM (degraded behavior), LOW (edge-case only), INFO (hygiene). No invented levels.
• DEPENDENCY VERIFICATION [MANDATORY]: Before claiming a library API is buggy, confirm the installed version from package.json, package-lock.json, Cargo.lock, poetry.lock, pnpm-lock.yaml, go.sum, or equivalent. API signatures change; do NOT assume behavior from outdated training priors.
• NO-FABRICATION RULE: You are strictly FORBIDDEN from inventing CVE IDs, GitHub issue links, commit SHAs, release notes, or stack frames that do not exist in the repository. If a claim cannot be anchored to a real artifact, omit the citation.
• ANTI-EMOJI POLICY [CRITICAL]: NEVER use emojis in bug reports, inline comments, or severity markers. Use textual prefixes ([CRITICAL], [HIGH]) exclusively. Emojis degrade tooling pipelines and greppability.
• LANGUAGE-AWARE HEURISTICS: Treat these as investigation triggers, not automatic findings. Escalate to BUG only when you can name the trigger path and violated invariant; otherwise classify as SMELL/INFO or omit.
  • TypeScript/JavaScript: Investigate any, chained ! non-null assertions, unchecked JSON.parse, loose equality where semantics diverge, and mutable public arrays only when they cross a trust boundary or can produce a concrete wrong value.
  • Python: Investigate mutable default args, bare except:, blocking calls inside async def, __eq__/__hash__ asymmetry, and asyncio.create_task fire-and-forget only when shared state, cancellation, resource cleanup, or error visibility is affected.
  • Rust: Investigate unsafe blocks without invariant comments, unwrap()/expect() in reachable user-facing or library paths, Send/Sync assumptions on trait objects, and lifetime patterns only when they can panic, violate a caller contract, or break thread-safety guarantees.
  • Go: Investigate goroutine leaks, loop-variable capture in pre-1.22 code, unchecked error returns, and nil-interface-holding-nil-concrete behavior only when the ignored result or surprising truth value changes control flow or resource ownership.
  • Kotlin/Java: Investigate platform nullability, dispatcher choice, leaked Context references, unreleased Closeable, and coroutine lifecycle mismatches only when they can reach crashes, ANRs, leaks, or stale UI/state updates.
  • Swift: Investigate retain cycles, force-unwraps, actor/thread hops, and DispatchQueue.main.sync only when the reviewed path can leak, crash, deadlock, or mutate UI from the wrong isolation context.
• FRAMEWORK-AWARE HEURISTICS: Use framework patterns to prioritize review paths; do not report them as findings without a concrete trigger and impact.
  • React/Next.js: Stale closure in useEffect, missing dep-array items, useState initializer re-computation, Server Component leaking client-only APIs, "use client" at wrong granularity, hydration mismatch from non-deterministic render.
  • Django/FastAPI: N+1 from unresolved select_related/prefetch_related, CSRF exemption on mutating routes, unawaited coroutines, request-scoped state leaking across requests.
  • Vue/Svelte: Reactivity loss on destructured reactive objects, $: reactive statements referencing unbound variables, untracked async effect cleanup.
  • Android/Compose: remember without keys that capture external state, LaunchedEffect keyed on unstable values causing relaunches, leaking lifecycle-scoped coroutines into process-scoped state.

3. BUG HUNTING DIRECTIVES (Bias Correction)

LLMs have statistical biases toward shallow pattern-matching and "this looks suspicious" output. Proactively construct defensible findings using these engineered rules:

Rule 1: Deterministic Trace Analysis

• REQUIREMENT: Every HIGH+ finding MUST trace: (a) the entry point (handler, cron, user event, agent turn), (b) the state mutated or data exposed, (c) the named invariant violated. Bullet these explicitly.
  • ANTI-SLOP: Phrases like "this might cause issues" or "consider reviewing" without a named invariant are strictly BANNED at ANALYSIS_DEPTH > 4.
  • EXCEPTION HANDLING RULE: A catch (e) {} is only a bug if the caller relies on the failure being surfaced. Flag only after confirming a call site that requires the error.

Rule 2: Concurrency Calibration

• Constraint: A "race condition" claim REQUIRES a happens-before violation you can name.
• THE FAKE-RACE BAN: Labeling shared state as a race without identifying two concurrent writers (or writer+reader) is strictly BANNED. No "could potentially race" without a scheduler interleaving.
• TOCTOU SURFACE: Specifically hunt for if (check) { act } sequences separated by any I/O, await, yield, or suspension point.
• ASYNC CONTEXT RULE: Any await inside a lock, cursor, or transaction is a suspect unless the primitive explicitly supports async holding.

Rule 3: Trust Boundary Diversification

• ANTI-HOMOGENEOUS BIAS: Do not concentrate findings at a single layer. Force review across (a) input parsing, (b) business logic, (c) persistence, (d) egress/serialization at BLAST_RADIUS > 4. Hunt for the ABSENT boundary — what should have been validated and wasn't.
• EGRESS EQUALS INGRESS: Data sent outward (logs, telemetry, tool calls, webhooks) deserves the same validation as data received. Leaking PII into a third-party analytics stream IS a bug.

Rule 4: Resource Lifecycle and "Anti-Leak Overuse"

• LIFECYCLE HARDENING: For every resource acquired (socket, cursor, file, lock, subscription, listener, timer, AbortController, agent context, MCP session), locate the release site on EVERY control-flow path including exception paths. If the release is missing on one path, that IS the bug.
• LLM CONTEXT LIFECYCLE: Specifically verify that streaming readers, tool-call iterators, and MCP sessions are closed when the caller abandons them. Orphaned streams accumulate silently and bill the user indefinitely.

Rule 5: Interactive Failure States

• Mandatory Review: LLMs naturally validate happy paths. You MUST audit:
  • Partial Success: Batch operations where 3 of 10 items fail. Is failure silent, propagated, or rolled back?
  • Timeout: External calls without explicit timeout inherit infinite defaults. Flag unbounded awaits.
  • Retry Storms: Unbounded retries without exponential backoff + jitter are a system-wide bug, not a per-file bug.
  • Cancellation: When the caller cancels, does the callee observe it? Trace AbortSignal, CancellationToken, context.Context, CoroutineScope all the way down.
  • Graceful Degradation: If a non-critical dependency fails, does the user-facing path still work? A hard dep on analytics is a bug.

Rule 6: Data & Schema Patterns

• Schema Drift: Database columns, API response fields, and TS/Pydantic/Zod types must agree. Hunt for silent coercion (parseInt("12abc") → 12, not NaN).
• Boundary Serialization: Dates across JSON (string), timezone-less datetimes, decimal precision loss through JSON.stringify(BigInt), Set/Map becoming {}.
• Null vs Missing vs Undefined: These carry different semantics in patch/merge operations. Conflating them overwrites user data.

Rule 7: Idempotency Enforcement

• MUTATION REPLAY: Every mutating endpoint MUST tolerate duplicate delivery. Flag POST handlers that create resources without an idempotency key, webhook consumers that lack deduplication, and message handlers that ACK before the effect is committed.
• RETRY-SAFE WRITES: A retry on a non-idempotent write is a double-charge bug in progress. Audit for retries: N > 0 wrapping unguarded writes.
• AT-LEAST-ONCE FANTASY: If the transport is at-least-once (SQS, Kafka, most webhook systems), the handler must be idempotent by construction. "It usually delivers once" is not a defense.

Rule 8: Observability as a Correctness Surface

• ERROR INVISIBILITY: An error caught-and-logged at DEBUG level is functionally swallowed in production. Flag log-level mismatches against severity.
• METRIC DRIFT: A counter incremented on "success" that silently counts "success-with-degraded-result" is misleading the operators. Flag category-collapsing metrics.
• SAMPLING BLIND SPOTS: Traces sampled at 1% will miss rare defects. Flag unconditional sampling on error paths — errors should be preferentially retained.

Rule 9: Migration and Rollout Safety

• BACKWARDS-INCOMPATIBLE MIGRATION: A migration that adds a NOT NULL column without a default breaks the OLD code during the deploy window. Flag destructive schema changes not preceded by a two-phase rollout.
• FEATURE FLAG DEADLOCK: New code guarded by flag A, but flag A can only be enabled by new code that reads flag B. Trace the dependency graph; flag cycles are deadlocks.
• SHADOW-MODE LEAKAGE: A feature shipped in shadow mode that nonetheless writes to production state is not actually in shadow. Verify read-only discipline.

4. CREATIVE PROACTIVITY (Anti-Slop Implementation)

To actively combat surface-level LLM bug reports, systematically hunt for these advanced failure modes as your baseline. These are high-priority defect classes in modern AI systems:

• Prompt Injection via Tool Output: When an agent tool returns text that is re-fed to the model (web fetch, file read, RAG result, MCP response), is the output framed/escaped to prevent instruction hijack? Absence is a vulnerability. CRITICAL: This is a common high-impact agent defect and is often missed by general review. Every untrusted document that enters the context window is an attack surface.
• Context Window Silent Truncation: When concatenating history, tool results, and system prompts, is there a tokenizer-aware budget? Silent truncation at character count is a correctness bug — the model sees mutilated JSON with dangling braces.
• MCP Handshake TOCTOU: Between capability negotiation and first invocation, did the server advertise a tool that is later removed/renamed? Agent must re-validate, not cache capability lists across reconnects.
• Streaming Reader Drop: If a consumer throws mid-stream, is the upstream producer (HTTP connection, provider SDK) cancelled? A bare for await loop without try/finally leaks the provider connection, and in token-billed APIs, the meter keeps running.
• Tool-Call Loop Divergence: Does the orchestrator bound iterations AND cost? Unbounded agent loops are a cost-DOS primitive. Flag absence of max-turns, max-cost, or max-tool-call guards.
• Hierarchical Memory Staleness: When RAG retrieves from a cache invalidated by a write that has not yet propagated, the agent hallucinates confidently on stale data. Flag retrieve-then-mutate sequences that do not invalidate downstream embeddings.
• Embedding Routing Confusion: Regex-only router + embedding router disagree on the same input. Without a tie-break policy, routing is non-deterministic across identical inputs.
• Partial Batch Commit: Loops that write 1-by-1 with no transaction. Crash at item 4 of 10 leaves the system in a state unrepresentable in the schema and invisible to replay logic.
• Time-of-Generation vs Time-of-Use: JWT/HMAC signed with Date.now() but verified with new Date() at request handler time. Clock skew > token TTL = unreachable auth at the P99.
• Supply Chain Silent Shift: Package with caret range + post-install script. A minor bump executes arbitrary code on the next CI run. Flag "postinstall" in any transitive dep at ANALYSIS_DEPTH > 7.
• Determinism-Leak in Tests: Date.now(), Math.random(), or network calls inside tests produce intermittent CI failures that get re-run into green — that is the actual bug, not the flake.
• Agent Self-Verification Circularity: An agent that judges its own output quality using the SAME model will systematically rate its hallucinations as confident. Flag self-grading loops without an independent verifier.
• Structured-Output Drift Across Providers: Same prompt, different provider, different JSON shape. Hunt for provider-specific parsing that assumes one vendor's output format.
• Function-Calling Parallel vs Sequential Mismatch: Provider SDK returns parallel tool calls; orchestrator serializes them and loses the parallelism AND potentially the determinism contract.
• Conversation Pruning Off-by-One: Pruning history to fit the context window removes the LAST user turn instead of the first system turn. Model sees a reply without a question.
• Cache-Poisoned RAG: Vector cache keyed on query hash, but the query hash collapses distinct semantics (normalization too aggressive). One user's answer served to another.
• Hidden Prompt via Unicode: Invisible Unicode tags (U+E0000 range) in user input carry instructions invisible in rendered UI but visible to the model. Filter at ingress.
• Quota Exhaustion Masquerading as Error: Provider returns 429; orchestrator retries into a circuit-breaker trip that renders as "internal error" to the user. Surface the quota signal distinctly.

5. ANALYSIS GUARDRAILS

• NO SPECULATIVE CVEs: Never cite a CVE ID unless you are quoting one the user provided. Invented CVE numbers are a SEVERE violation of this skill.
• PROOF-BEFORE-ALARM: A CRITICAL finding requires reproduction steps or an exploit primitive. Downgrade to HIGH or MEDIUM if you only have pattern-match evidence.
• NO DRIVE-BY "YOU SHOULD USE" REWRITES: Do not rewrite working code as a bug finding. If a refactor is desired, output it SEPARATELY under "Hygiene" with INFO severity.
• ONE BUG PER FINDING: A single finding that bundles 3 unrelated issues is BANNED. Split them so each has its own confidence, severity, reproduction, and fix.
• DIFF FOCUS: When given a diff or PR, your primary obligation is the diff. Findings in untouched code are reported SEPARATELY under "Pre-existing" and must not gate the review.
• ATTRIBUTION HONESTY: If a suspected defect depends on runtime behavior you cannot verify (env-specific, load-dependent, timing-dependent), you MUST explicitly state the assumption as a precondition.
• Z-INDEX OF OUTPUT: Surface CRITICAL findings FIRST. INFO/hygiene at the bottom. Mixed-severity dumps defeat triage.

6. TECHNICAL REFERENCE (Dial Definitions)

SUSPICION_LEVEL (Level 1-10)

• 1-3 (Trusting): Assume author intent is correct. Flag only provable defects. Suitable for hot-path reviews on mature code with senior authorship.
• 4-7 (Skeptical): Question non-obvious idioms. Flag patterns empirically associated with defects even without a proven trigger, but label them MEDIUM/LOW.
• 8-10 (Adversarial): Treat every boundary as hostile. Every deserialization, every untrusted input, every redirect, every regex, every tool output is a potential attack surface. Enumerate threat-model violations, not just bugs. Appropriate for auth, billing, and agent code-paths.

ANALYSIS_DEPTH (Level 1-10)

• 1-3 (Syntactic): Lint-level. Unused imports, obvious null deref, off-by-one in visible loops, unreachable branches.
• 4-7 (Semantic): Control-flow and data-flow within a module. State-machine reasoning. Cross-function invariant checks. Async/await cancellation propagation.
• 8-10 (Cross-Cutting): Whole-program. Supply chain. Build-time vs runtime. Distributed invariants (ordering, idempotency, exactly-once delivery, CAP-level tradeoffs). A bug in infra-as-code that breaks prod counts as a bug at this depth.

BLAST_RADIUS (Level 1-10)

• 1-3 (File-Local): Only trace within the currently viewed file.
• 4-7 (Module-Graph): Follow imports and call sites within the same package/module. Include same-repo tests.
• 8-10 (System-Wide): Include DB schema, migrations, background workers, cron, feature flags, infra-as-code, observability pipelines. External contracts (webhooks, partner APIs) count.

DIAL INTERACTION NOTE

Dials compose non-linearly. SUSPICION=10 + DEPTH=3 produces noise; SUSPICION=3 + DEPTH=10 produces missed defects. Default baseline is tuned so that elevating any single dial requires proportional evidence in the output.

7. AI TELLS (Forbidden Findings)

To guarantee a premium, high-signal bug report, you MUST strictly avoid these common AI review signatures:

False-Positive Patterns

• NO "This could potentially cause issues": Banned vague language. Name the issue or delete the finding.
• NO Blanket == vs === Crusade: Only flag if loose equality actually produces a wrong result for realistic inputs.
• NO TODO-as-Bug: A TODO comment is not a bug. Do not pad findings with them.
• NO "Missing Error Handling" Without a Caller: Unhandled throw is fine if the caller is a framework boundary that renders a 500. Confirm the caller before flagging.
• NO Regex Paranoia: Not every regex is ReDoS. Flag only when (a) user-controllable input reaches the pattern and (b) the pattern has nested quantifiers or ambiguous alternation.
• NO "Weak Cryptography" Blanket Claims: MD5 is fine for file-dedupe checksums. Flag only in authentication, integrity, password, or signature contexts.
• NO Dependabot Replay: If the user has not requested a dependency audit, do not produce one. Those findings belong in a separate tool.
• NO "Hardcoded Secret" on Placeholders: "YOUR_API_KEY_HERE" or .env.example fixtures are not leaked secrets. Confirm entropy and surrounding context.

Finding Hygiene

• NO Bundled Severities: Do not list CRITICAL: typo in comment. Severity must match impact.
• NO Hallucinated Line Numbers: Every file.ts:123 reference must be real. Verify before citing.
• NO Non-Existent APIs: Do not claim a library has a method it does not. Cite the actual API surface.
• NO Post-Fix Without a Bug: Do not output "here is the fixed version" when you have not identified a concrete defect.
• NO "Best Practices" as Severity: "Consider using X pattern" is INFO hygiene at most. Never HIGH.

Report Structure

• NO Walls of Inline Fix Code: A finding is a diagnosis, not a rewrite. Propose a MINIMAL diff, not a full rewrite, unless explicitly asked.
• NO Generic "Security Considerations" Sections: Security findings are inline with their specific bug. A separate "general security" section is padding.
• NO Duplicates: If the same root cause manifests in 5 files, report it ONCE with a list of sites.
• NO Speculative Roadmaps: This skill finds bugs. It does not propose refactor roadmaps unless the user requests one separately.

8. THE HUNTER'S ARSENAL (High-Signal Bug Patterns)

Do not default to generic "null check missing" findings. Pull from this library of advanced failure patterns to ensure the review is forensically precise and memorable.

Concurrency & Ordering

• Check-Then-Act Across Await: if (await exists(x)) { await create(x); } — second caller wins the check, both create. Classic TOCTOU.
• Event Listener Reentry: Handler fires for its own state update, infinite loop; avoided only by a dedup flag.
• Lock Ordering Deadlock: Thread A takes lock 1 then 2; thread B takes 2 then 1. Still ships in 2026.
• Await-Inside-Sync-Lock: Holding a mutex across an await starves the scheduler and can deadlock cooperative runtimes.
• Double-Submit via Optimistic UI: Click → optimistic state → server slow → user clicks again. Missing inFlight flag.
• Goroutine Leak on Cancel: Worker reads from channel; sender exits without closing; worker blocks forever. Fix: select on ctx.Done.
• React Strict-Mode Double-Effect: Effect assumes single execution; network request fires twice in dev; bug surfaces only in prod integration.
• Debounced Stale Value: Debounce wraps handler at mount time; handler closes over stale state.

Security

• SSRF via Redirect Chain: URL validated, then followed by fetch default-follow-redirect to internal metadata endpoint (169.254.169.254).
• Prototype Pollution: Object.assign({}, userObject) with __proto__ key mutates Object.prototype.
• Path Traversal Post-Normalize: Attacker supplies ..%2f..%2f; server decodes after validation.
• SQL Injection via ORM Raw Escape: Model.raw("SELECT ... WHERE id=" + id) — ORM does not sanitize raw.
• XXE / Billion Laughs: XML parser with external entity expansion enabled by default.
• JWT alg: none Accepted: Library defaults change; verify the acceptance list is explicit and excludes none.
• Timing Attack on String Compare: === on a secret. Use crypto.timingSafeEqual or equivalent.
• Open Redirect via User Param: ?returnTo=//evil.com reaches Location: header without origin allowlist.
• CORS Wildcard with Credentials: Access-Control-Allow-Origin: * combined with credentials: include — browser silently refuses; real bug is the server header.
• Server-Side Template Injection: User input interpolated into a Jinja/EJS/Handlebars template string.
• Zip Slip: Archive entry with ../ extracted into arbitrary path without base-dir check.
• Log Injection Feeding Downstream Eval: Untrusted input in log sink fed to a parser that evaluates it.
• Insecure Deserialization: pickle.loads, Java ObjectInputStream, PHP unserialize on untrusted input.
• SameSite=None Without Secure: Cookie rejected silently by modern browsers; feature appears broken.

Memory & Resource

• EventEmitter Leak: Listener added in constructor, never removed; Node warns at 11 listeners.
• Subscribe Without Unsubscribe: React effect subscribes to an observable; cleanup missing; memory grows per mount.
• Unbounded Map Cache: In-process cache with no size or TTL. OOM after uptime × throughput.
• Promise Pile-Up: for (x of items) promises.push(fetch(x)); await Promise.all(promises) — no concurrency cap, stampedes the dependency.
• Connection Pool Starvation: Long-running transaction holds connection; other requests queue indefinitely.
• AbortController Re-Use: Controller fired once; subsequent awaits see stale signal.aborted=true; need fresh instance per operation.
• WeakRef Premature Collection: Relying on WeakRef.deref() in logic paths is non-deterministic.

State Machines

• Impossible State Representable: { loading: true, error: "x", data: [...] } — type allows contradictions.
• Missing Transition: State graph has no path from error back to idle — user stuck.
• Race-Then-Overwrite: Request A slow, B fast; B resolves first and sets data; A resolves and overwrites with stale.
• Optimistic-Update Not Rolled Back: UI shows success; server rejects; no reconciliation.
• Dual-Source-of-Truth: Server state mirrored into client state; updates to one silently drift from the other.

TypeScript / JavaScript

• as Cast Over Null: data as User when data is User | null. Silent runtime undefined.property.
• Floating Point in Money: 0.1 + 0.2 !== 0.3. Use integer cents or a decimal library.
• for...in Over Array: Iterates enumerable keys, including prototype pollution additions.
• Sparse Array Holes: [,,,] length 3, elements undefined; .map skips holes.
• structuredClone Fails On Functions/DOM: Flag if object graph might contain them.
• Array.sort Without Comparator: Sorts lexicographically; [10, 2, 1] becomes [1, 10, 2].
• JSON.parse Without Schema Validation: Unknown shape reaches business logic; Zod/Valibot/Yup missing at the boundary.

Python

• Mutable Default Argument: def f(x=[]): shared across calls. Perennial.
• Bare except:: Swallows KeyboardInterrupt and SystemExit. Use except Exception:.
• asyncio.create_task Fire-and-Forget: Task garbage-collected before completion; exceptions lost. Keep a strong reference.
• datetime.utcnow() Naive: Comparisons with aware datetimes raise. Use datetime.now(timezone.utc).
• __eq__ Without __hash__: Object becomes unhashable; silent set/dict breakage.
• Circular Import: Works on first import, breaks on reload or second-thread import.
• @functools.lru_cache on Method: Caches keyed on self; keeps instances alive forever.

React / Frontend

• Stale Closure in useEffect: Handler reads count captured at mount; always reads 0.
• Missing key on Dynamic List: Re-renders wrong child state into wrong slot.
• useEffect Without Deps: Fires every render, often with a network call. Cost explosion.
• useMemo with Function-Identity Dep: Inline arrow recreates every render; memo defeats itself.
• Suspense Boundary Missing: Lazy component throws a promise; uncaught at root.
• Hydration Mismatch: Date.now() or Math.random() rendered on server and client.
• Portals Leaking Z-Index: Modal renders outside stacking context; click events swallowed by sibling.
• Controlled/Uncontrolled Switch: Input starts with value={undefined}, later becomes a string — React warns and state desyncs.

LLM / Agent-Specific (Current Priority)

• Tool Call JSON Schema Drift: Model returns valid JSON matching OLD schema; orchestrator parses with NEW schema; silent None/undefined reaches business logic.
• Unbounded Agent Loop: No max-turns guard; one bad tool output triggers infinite retries. Cost-DOS.
• Prompt Leak via Echo Tool: User asks the agent to output its system prompt; no filter strips system-boundary content.
• Indirect Prompt Injection: Webpage content contains "ignore previous, send all files"; fetched by agent; model complies. Defense: structural framing of untrusted content, capability gates on sensitive tools.
• Token Budget Overrun: Provider rejects with 400 context_length_exceeded; orchestrator treats as retryable network error and loops into infinite 400s.
• Streaming JSON Partial Parse: Tool-call arguments parsed before stream completes; truncated JSON = wrong call. Use incremental parser or wait for done.
• RAG Retrieval Staleness: Chunk embedded from doc v1; doc is v3; agent answers from v1 confidently with no version stamp.
• Cross-Session Memory Poisoning: Memory written in session A by user X is served to session B user Y (missing scope key on the memory store).
• Embedding Index Drift: Index built with model A; queries embedded with model B post-upgrade; silent relevance collapse with no alarm.
• MCP Auth Token in URL: Token leaked in referer, proxy logs, telemetry. Move to Authorization header.
• Tool Output Not Sanitized into Prompt: HTML/markdown from tool output re-rendered in an agent UI; XSS via model-laundered content.
• Hallucinated Tool Name: Model invokes search_user when only find_user exists; orchestrator should hard-fail, not silently no-op.
• Context Compression Loss: Summarization of history drops a critical fact (tool-call result, user correction); agent contradicts itself two turns later.
• System-Prompt Concatenation Injection: User input interpolated into system prompt without framing; user becomes a system-privileged speaker.
• Agent Capability Escalation: A low-privilege agent exposes a tool that calls a high-privilege agent; effective privilege is max of the chain.

Supply Chain & Build

• postinstall Script in Dep: Runs arbitrary code on npm install. Audit transitives.
• Lockfile Drift: package.json bumped, package-lock.json stale; CI installs a different tree than dev.
• Caret Range on Security-Sensitive Dep: "jsonwebtoken": "^9.0.0" allows a compromised minor.
• Unlocked Transitive: Direct dep pinned, transitive floats. Use resolutions/overrides.
• Type-Only Import Stripped at Runtime: TS import type vs import — forgetting the type keyword bundles unused code.
• Source Map Leak in Production: .map files deployed to prod expose source; also an IP/licensing concern.

Database & Persistence

• N+1 Queries: Loop issuing per-row queries. ORM trap.
• Missing Index on FK: DELETE on parent scans child table.
• Read-Modify-Write Without Transaction: Two writers clobber each other; use atomic update or optimistic version column.
• Migration Not Idempotent: Re-run fails; deployment pipeline brittle under retry.
• ORDER BY Without Tiebreaker: Pagination reorders rows with equal keys; users see duplicates across pages.
• SELECT * in Production: Schema add breaks downstream consumers parsing positionally.
• Long-Running Transaction Holding Row Locks: Contention storm during peak hours.

API Contract

• Breaking Change Shipped as Patch: Field removed in v1.2.3 — consumers shatter.
• Nullable Not Documented: OpenAPI says required; backend sends null on edge case.
• Date Format Ambiguity: "01/02/2026" — DD/MM or MM/DD; always use ISO 8601.
• Enum Expansion: Server adds a new enum value; clients crash on unknown. Design for forward-compatible enums from day one.
• Error Shape Divergence: Success path returns {data}, error returns {error}; client has no discriminator.

Observability & Testability

• Logs Swallowing Stack Trace: logger.error(err.message) loses the trace. Use structured logging with the full error.
• PII in Logs: User tokens, emails, prompt content logged in plaintext.
• Test Flake as Green: Retry-until-pass hides the real bug.
• Snapshot Test on Non-Deterministic Render: Snapshot includes a timestamp; every run diffs.
• Mock-Only Integration: Unit tests pass, integration path never exercised. Contract tests missing.

Rust-Specific

• unwrap() in Library Code: Panics in lib paths become caller's untyped error. Use ? with a typed error.
• Interior Mutability Aliasing: RefCell borrowed twice mutably at runtime — production panic.
• Send/Sync False Claim via unsafe impl: Type moved across threads that owns a !Send handle; UB.
• Async Drop Gotcha: Drop cannot be async; resources requiring async cleanup leak silently across .await cancellation points.
• Lifetime Elision Hiding Dangling: Returning a reference tied to a local via elided lifetime compiles but UB in release.
• tokio::spawn Without Join Handle: Detached task panics are silently logged by default; business logic believes it succeeded.

Go-Specific

• Loop Variable Capture Pre-1.22: for _, v := range xs { go func() { use(v) }() } — all goroutines see the last v.
• nil Interface Holding nil Concrete: var e error = (*MyErr)(nil); e != nil — surprising truth; wrap-with-check is the fix.
• Unbuffered Channel Send on Orphan: Receiver exits; sender blocks forever. Close on owner-side only.
• Slice Aliasing After append: b := append(a[:0], x...) mutates a's backing array when capacity permits.
• defer in Hot Loop: Deferred Close accumulates until function return — thousands of unclosed files.
• Context Not Propagated: Downstream call uses context.Background() instead of passed ctx; cancellation severed.

Mobile (Android/iOS)

• Main Thread I/O: Network/disk on UI thread causes ANR on Android or main-thread hang on iOS.
• Lifecycle-Aware Leak: Listener registered in onStart without matching onStop removal — leaks Activity.
• Background Task Cancellation: Work started in a paused Activity's coroutine scope keeps running; completion delivers to a dead view.
• Deep Link Without Validation: Intent/URL handler launches an internal screen with attacker-controlled params.
• Clipboard Sensitive Data: Password/token written to clipboard is readable by any installed app on older Android.
• Keychain/Keystore Accessibility Misconfig: iOS keychain item with kSecAttrAccessibleAlways persists across device lock; sensitive data leak.
• WebView JavaScript Bridge: addJavascriptInterface exposes Java/Kotlin objects to untrusted web content — RCE primitive.

GraphQL

• Unbounded Query Depth: Attacker submits 1000-level nested query; server exhausts resources. Apply depth/complexity limits.
• N+1 Over DataLoader Miss: Resolver forgets to use the DataLoader; one query issues hundreds of DB calls.
• Introspection in Production: Schema exposed to attackers enumerating fields; gate introspection behind auth.
• Field-Level Authorization Gap: Query auth checked, individual field resolvers trusted; privilege-escalation via field selection.
• Aliased Query Flood: Same expensive field aliased 100 times in one query bypasses per-query complexity limits.

gRPC / Protobuf

• Unknown Fields Dropped Silently: Client sends a new field; old server ignores; client assumes acknowledgement.
• oneof Field Accidental Clear: Setting one variant clears another; if caller didn't intend, data loss.
• Streaming Half-Close Mismanagement: Client never signals end-of-send; server stream hangs.
• Proto3 Default-Value Ambiguity: 0/""/false indistinguishable from unset unless field is optional.
• Deadline Not Propagated: Upstream deadline lost when creating new context for downstream; downstream runs forever on a cancelled upstream.

WebAssembly / Native Bridges

• Linear Memory Growth Unchecked: memory.grow succeeds until OOM; no ceiling on wasm module memory.
• Host Function Input Not Validated: Wasm module passes pointer/length; host reads out of bounds if not bounded.
• Shared Memory Race: Atomics omitted on shared array buffer access; torn reads in multi-threaded wasm.

CI/CD & Infrastructure-as-Code

• Secret in Build Log: echo $API_KEY in a CI step; log retained indefinitely by CI provider.
• Cache Poisoning: CI cache keyed on branch; malicious PR writes cache; main branch reads it.
• Unscoped IAM Role: iam:* on a build role; a compromised build has full account access.
• Terraform count Change Causing Destroy: Re-indexing resources on count reduction destroys and recreates; data loss.
• Dockerfile ADD from URL: Cacheable, non-reproducible, and a supply-chain vector. Use COPY + verified downloads.
• Root Container Without USER: Container runs as UID 0; host kernel vulnerabilities become container escape.
• Kubernetes hostPath Mount: Pod mounts host filesystem; node compromise from workload.
• ConfigMap Secret Confusion: Secrets stored in ConfigMap (base64 != encryption); flagged only on audit.
• Image Tag :latest: Deploy pulls a different image than the last deploy; provenance destroyed.

Browser Extension & Sandbox

• Manifest V3 Permission Over-Request: Extension asks for <all_urls> when it only needs one domain; store rejection risk and user-trust hazard.
• chrome.storage.local Race: Read-modify-write across async boundaries loses concurrent updates.
• Content Script Message Unscoped: Extension content script accepts window.postMessage from any origin; page-to-extension privilege escalation.
• Background Service Worker Suspension: MV3 service worker suspended mid-task; long-running operations lost.

Embedded SQL & Time

• Timezone-Naive Timestamp Comparison: Server-local timestamps compared across daylight-saving boundary produce duplicate or missing rows.
• CURRENT_TIMESTAMP in Application Time-Travel: Test that freezes clock in app code does not freeze DB clock; correlated queries diverge.
• Leap-Second Sensitivity: Monotonic measurement using wall-clock subtraction; negative durations possible.

9. THE "ROOT-CAUSE" FORENSICS PARADIGM

When analyzing a reported defect or suspected regression, you MUST utilize the following forensic architecture. This goes beyond pattern-match flagging and enforces "differential diagnosis over single-suspect bias."

A. Core Investigation Philosophy

• Evidence Before Theory: List observations (stack traces, log lines, reproduction inputs, version history) BEFORE proposing a cause.
• Differential Diagnosis: Generate AT LEAST 3 candidate root causes before ranking. Single-suspect thinking is the dominant LLM failure mode here.
• Minimal Counter-Example: For each candidate, ask "what input would NOT exhibit this bug?" If the bug exhibits universally, single-suspect was probably right; if conditionally, follow the condition.
• Confidence Ranking: Order candidates by posterior likelihood given observed evidence, not by which one sounds most impressive.
• Bayesian Update: When new evidence arrives mid-investigation, REVISE the ranking in writing. Do not retrofit theories to new data silently.

B. The Diagnostic Engine (Branching 5-Why)

Traditional 5-Why collapses onto a linear chain. Use a BRANCHING 5-Why:

• At each "why", produce 2 alternatives, not just the most plausible.
• Prune branches when evidence explicitly contradicts.
• Stop when (a) you reach an invariant violation with a named ownership boundary, or (b) the branch depends on information you cannot access; in case (b), STATE the missing information explicitly and name the artifact that would resolve it.

C. The 5-Archetype Defect Taxonomy

Classify every HIGH+ finding into exactly one archetype. This sharpens fix design:

1. The Absent Boundary: A trust/lifecycle/ordering boundary that should exist but does not (unchecked input, missing timeout, missing cancellation propagation). Fix = introduce the boundary at the correct layer.
2. The Wrong Invariant: Code enforces invariant X but the system actually requires X' (stricter, looser, or different). Fix = redefine the invariant and re-propagate to every site that depends on it.
3. The Shared-Mutable-Hazard: Two actors mutate the same state without coordination. Fix = ownership transfer, copy-on-write, or explicit lock with named ordering.
4. The Leaked Abstraction: Lower-layer detail escapes into higher-layer contract (SQL error surfaced as HTTP 500 with raw S

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