/challenge
Use before a root-cause, done/verified claim, irreversible action, or 2nd-time fix reaches the owner (APEX or plain conversation); also fires at every eLicit/Verify gate. Not for code correctness (use sniper).
$ npx -y skills add fusengine/agents --skill challenge --agent claude-codeHow it fires
How this skill gets triggered: by you, by Claude, or both.
- Fires itselfAuto-invocation. Claude auto-loads it when your prompt matches the work.
- You can call itInvoke it directly when you want it.
- Slash command
/challenge
Context preview
The summary Claude sees to decide when to auto-load this skill.
Use before a root-cause, done/verified claim, irreversible action, or 2nd-time fix reaches the owner (APEX or plain conversation); also fires at every eLicit/Verify gate. Not for code correctness (use sniper).
SKILL.md
challenge.SKILL.mdname: challenge
description: "Use before a root-cause, done/verified claim, irreversible action, or 2nd-time fix reaches the owner (APEX or plain conversation); also fires at every eLicit/Verify gate. Not for code correctness (use sniper)."
<objective> Challenge is the adversarial verification protocol behind the `challenger` agent: refute-by-default, fresh-context intake (claim + evidence only, never the author's reasoning), sources-backed (Context7 -> Exa -> fuse-browser -> code), bounded to 2 refutation rounds ending in a mandatory verdict (CONFIRMED / REFUTED / UNCERTAIN). It is consultative, not a veto -- it reports the strongest objection and leaves the decision to the lead/owner.
It fires systematically by claim TYPE, not by a stakes judgment: before a root-cause conclusion, a done/verified claim, an irreversible action (commit/deploy/rm/push), or a 2nd-time fix reaches the owner, whether inside an APEX task or in plain conversation -- plus automatically at every APEX eLicit round and Verify gate. It does not cover code correctness, lint, or type validation -- that stays sniper's lane at eXamine. </objective>
Challenge Skill
Reusable protocol behind the `challenger` agent. Also usable directly inside any expert agent's own eLicit step when a dedicated agent call is overkill -- the discipline is the same either way.
The 7 Principles
1. **Refute by default** -- a claim is FALSE until proven otherwise. Never "are you sure?" -- always a concrete failure scenario + the untested hypothesis it exposes. 2. **Fresh context mandatory** -- intake is the claim + its evidence ONLY, never the author's reasoning. Inheriting the author's angle reproduces the author's blind spot. 3. **Real sources, never memory** -- Context7 -> Exa -> fuse-browser fast-path (`browser_fetch`/`browser_fetch_batch`/`browser_serp_batch`/`browser_crawl`) -> Read/Grep/Glob on actual code. Docs and code beat recollection. 4. **Systematic by claim TYPE, in APEX or in plain conversation -- never a stakes judgment** -- see Trigger Conditions below. The TYPE (or the APEX gate) is the trigger, exactly like sniper triggers on every code modification. 5. **Bounded** -- max 2 refutation rounds, then a mandatory verdict. No open-ended ping-pong. 6. **Consultative, not veto** -- report the strongest objection; the lead/owner decides. Read-only, edits nothing. 7. **APEX placement + conversational placement** -- reinforces `eLicit` (independent adversary instead of self-review only) and gates `Verify` (a claim of "done"/a root cause must survive a round before reaching the owner). Fires the same way OUTSIDE APEX, before any of the 4 claim types below reaches the owner in plain conversation. Does NOT touch `eXamine` -- that's sniper's code-correctness lane.
Trigger Conditions (systematic by claim TYPE, in APEX or in plain conversation -- like sniper on every code modification)
Runs automatically, no stakes judgment, before the lead reports to the owner any of these 4 TYPES -- whether inside an APEX task or in plain conversation:
- A root-cause conclusion ("it's broken because X" / "the reason is Y")
- A "done/verified/it works" claim
- An irreversible action about to run (commit / deploy / `rm` / push)
- A fix/explanation proposed a 2nd time
Also runs automatically at, in APEX specifically:
- Every eLicit round (Step 4/5 boundary -- challenge the elicitation's own findings/fixes)
- Every Verify gate (before a "done/verified" claim reaches the owner)
This is a scope by claim TYPE, not a reduced-coverage shortcut -- the 3 real failures that motivated this skill were all CONVERSATIONAL claims to the owner, none inside an APEX task with eLicit/Verify. A challenger that only fired on APEX gates would have missed all three. "Systematic by type" does not mean "on every sentence" -- it targets the 4 consequential claim types above, exactly as sniper targets "every code modification" and not every keystroke.
Protocol Steps
| Step | Action | |------|--------| | 0. Intake | Receive claim + evidence verbatim. Discard any leaked reasoning/narrative before starting. | | 1. Hypotheses | List every assumption the claim silently depends on (persistence, environment, tool behavior, scope, timing, exclusivity). | | 2. Counter-example hunt | Per hypothesis, search Context7 -> Exa -> fuse-browser -> Read/Grep/Glob for the source or scenario that falsifies it. | | 3. Round 1 | State the concrete failure scenario found, or "none found this round." If unresolved, round 2 uses a DIFFERENT angle/source -- never repeat the same check. | | 4. Round 2 + verdict | Deepen once more, then ALWAYS produce a verdict. Never continue past round 2. |
Output Format (mandatory)
VERDICT: CONFIRMED | REFUTED | UNCERTAIN
Claim challenged: <verbatim claim>
Failure scenario (concrete): <exact breaking input/condition, or "none found">
Untested hypotheses: [...]
Sources checked: [Context7: ..., Exa: ..., fuse-browser: ..., code read: <file:line>]
What remains to verify (if UNCERTAIN): <the specific check that resolves it>
Recommendation: <escalate to owner / safe to proceed / block until re-verified>
Integration with APEX
Analyze -> Plan -> Execute -> eLicit [+ CHALLENGE: independent adversary] -> [VERIFY gate: claim survives challenge] -> eXamine (sniper, code only)
- **eLicit**: the self-review pass gets a second, independent adversarial pass using this protocol -- an agent challenging its own claim inherits its own blind spot, so the challenge MUST run fresh-context (principle 2). ALWAYS, every eLicit round -- NO EXCEPTIONS.
- **Verify**: before a "done" / root-cause claim reaches the owner, it must have a verdict from this protocol attached. ALWAYS, every Verify gate -- NO EXCEPTIONS.
- **Outside APEX (plain conversation)**: before the lead reports any of the 4 claim types (root-cause / done-verified / irreversible action / 2nd-time fix) to the owner, ALWAYS -- NO EXCEPTIONS, regardless of whether an APEX task is runn
Read more
name: challenge description: "Use before a root-cause, done/verified claim, irreversible action, or 2nd-time fix reaches the owner (APEX or plain conversation); also fires at every eLicit/Verify gate. Not for code correctness (use sniper)."
<objective> Challenge is the adversarial verification protocol behind the `challenger` agent: refute-by-default, fresh-context intake (claim + evidence only, never the author's reasoning), sources-backed (Context7 -> Exa -> fuse-browser -> code), bounded to 2 refutation rounds ending in a mandatory verdict (CONFIRMED / REFUTED / UNCERTAIN). It is consultative, not a veto -- it reports the strongest objection and leaves the decision to the lead/owner.
It fires systematically by claim TYPE, not by a stakes judgment: before a root-cause conclusion, a done/verified claim, an irreversible action (commit/deploy/rm/push), or a 2nd-time fix reaches the owner, whether inside an APEX task or in plain conversation -- plus automatically at every APEX eLicit round and Verify gate. It does not cover code correctness, lint, or type validation -- that stays sniper's lane at eXamine. </objective>
Challenge Skill
Reusable protocol behind the `challenger` agent. Also usable directly inside any expert agent's own eLicit step when a dedicated agent call is overkill -- the discipline is the same either way.
The 7 Principles
1. **Refute by default** -- a claim is FALSE until proven otherwise. Never "are you sure?" -- always a concrete failure scenario + the untested hypothesis it exposes. 2. **Fresh context mandatory** -- intake is the claim + its evidence ONLY, never the author's reasoning. Inheriting the author's angle reproduces the author's blind spot. 3. **Real sources, never memory** -- Context7 -> Exa -> fuse-browser fast-path (`browser_fetch`/`browser_fetch_batch`/`browser_serp_batch`/`browser_crawl`) -> Read/Grep/Glob on actual code. Docs and code beat recollection. 4. **Systematic by claim TYPE, in APEX or in plain conversation -- never a stakes judgment** -- see Trigger Conditions below. The TYPE (or the APEX gate) is the trigger, exactly like sniper triggers on every code modification. 5. **Bounded** -- max 2 refutation rounds, then a mandatory verdict. No open-ended ping-pong. 6. **Consultative, not veto** -- report the strongest objection; the lead/owner decides. Read-only, edits nothing. 7. **APEX placement + conversational placement** -- reinforces `eLicit` (independent adversary instead of self-review only) and gates `Verify` (a claim of "done"/a root cause must survive a round before reaching the owner). Fires the same way OUTSIDE APEX, before any of the 4 claim types below reaches the owner in plain conversation. Does NOT touch `eXamine` -- that's sniper's code-correctness lane.
Trigger Conditions (systematic by claim TYPE, in APEX or in plain conversation -- like sniper on every code modification)
Runs automatically, no stakes judgment, before the lead reports to the owner any of these 4 TYPES -- whether inside an APEX task or in plain conversation:
- A root-cause conclusion ("it's broken because X" / "the reason is Y")
- A "done/verified/it works" claim
- An irreversible action about to run (commit / deploy / `rm` / push)
- A fix/explanation proposed a 2nd time
Also runs automatically at, in APEX specifically:
- Every eLicit round (Step 4/5 boundary -- challenge the elicitation's own findings/fixes)
- Every Verify gate (before a "done/verified" claim reaches the owner)
This is a scope by claim TYPE, not a reduced-coverage shortcut -- the 3 real failures that motivated this skill were all CONVERSATIONAL claims to the owner, none inside an APEX task with eLicit/Verify. A challenger that only fired on APEX gates would have missed all three. "Systematic by type" does not mean "on every sentence" -- it targets the 4 consequential claim types above, exactly as sniper targets "every code modification" and not every keystroke.
Protocol Steps
| Step | Action | |------|--------| | 0. Intake | Receive claim + evidence verbatim. Discard any leaked reasoning/narrative before starting. | | 1. Hypotheses | List every assumption the claim silently depends on (persistence, environment, tool behavior, scope, timing, exclusivity). | | 2. Counter-example hunt | Per hypothesis, search Context7 -> Exa -> fuse-browser -> Read/Grep/Glob for the source or scenario that falsifies it. | | 3. Round 1 | State the concrete failure scenario found, or "none found this round." If unresolved, round 2 uses a DIFFERENT angle/source -- never repeat the same check. | | 4. Round 2 + verdict | Deepen once more, then ALWAYS produce a verdict. Never continue past round 2. |
Output Format (mandatory)
VERDICT: CONFIRMED | REFUTED | UNCERTAIN Claim challenged: <verbatim claim> Failure scenario (concrete): <exact breaking input/condition, or "none found"> Untested hypotheses: [...] Sources checked: [Context7: ..., Exa: ..., fuse-browser: ..., code read: <file:line>] What remains to verify (if UNCERTAIN): <the specific check that resolves it> Recommendation: <escalate to owner / safe to proceed / block until re-verified>
Integration with APEX
Analyze -> Plan -> Execute -> eLicit [+ CHALLENGE: independent adversary] -> [VERIFY gate: claim survives challenge] -> eXamine (sniper, code only)
- **eLicit**: the self-review pass gets a second, independent adversarial pass using this protocol -- an agent challenging its own claim inherits its own blind spot, so the challenge MUST run fresh-context (principle 2). ALWAYS, every eLicit round -- NO EXCEPTIONS.
- **Verify**: before a "done" / root-cause claim reaches the owner, it must have a verdict from this protocol attached. ALWAYS, every Verify gate -- NO EXCEPTIONS.
- **Outside APEX (plain conversation)**: before the lead reports any of the 4 claim types (root-cause / done-verified / irreversible action / 2nd-time fix) to the owner, ALWAYS -- NO EXCEPTIONS, regardless of whether an APEX task is runn
Showing the first part of this file.
A plugin ecosystem that turns Claude Code into a supervised, multi-agent development environment.
Repo: fusengine/agents
Other skills on fusengine-agents.
- /agent-creator
Use when creating expert agents. Generates agent.md with frontmatter, hooks, required sections, and skill references.
Open skill - /apex-methodology
Use when starting ANY development task -- feature, bug fix, refactor, hotfix (triggers: implement, create, build, fix, add feature, refactor, develop).
Open skill - /brainstorming
Use when creating a feature/component or adding functionality. Fires BEFORE APEX Analyze to refine requirements via structured questioning.
Open skill - /code-quality
Use when validating code quality after modifications -- SOLID compliance, DRY duplication, linter errors, architecture violations. Do NOT use for functional verification (run verification FIRST, then code-quality).
Open skill - /elicitation
Use when an expert agent self-reviews and self-corrects code after the Execute phase, before sniper validation (BMAD-METHOD elicitation techniques).
Open skill - /exploration
Use when exploring an unfamiliar codebase -- architecture analysis, pattern detection, dependency mapping, rapid discovery.
Open skill

