Verify Before Plan

A premise is anything the orchestrator's plan asserts about the world without having looked: "there are 41 SKILL.md files that need editing," "the deprecated endpoint still has callers," "build is green on main," "the agent must rewrite the manifest." Before a wave of parallel subagents fans out against that premise, verify it with a small read-only probe. A wrong premise propagates to every brief in the wave and wastes an entire wave's worth of work — restarting is the only honest salvage.

When to Use This Skill

Use this skill when...	Skip when...
About to dispatch ≥2 parallel agents whose briefs cite a number, state, or path	Single-agent delegation — verify inline
The premise was carried in from an earlier message and not re-checked this session	The premise was produced by a tool call earlier in this same session
The user's report describes a symptom; the plan cites a cause	Waves entirely independent of repo state (e.g. brainstorming)
The plan assumes a tool/library/agent does X based on its name or docs	The behaviour is covered by a passing test the wave will re-run
The plan inherits a premise from another agent's return contract	The return contract already cites file:line evidence for the premise

This skill sits before parallel-agent-dispatch in the dispatch sequence. parallel-agent-dispatch covers the contract; this skill covers the assumption the contract is built on.

The Verification Protocol

Step 1: Name the premise

State the load-bearing facts in one or two sentences, in the form the wave's briefs will reference. Numbers, paths, and "does X" claims must be explicit — "all the affected plugins" is not yet a premise.

Step 2: Pick the cheapest verifier

Premise shape	Verifier
File count / "N occurrences of …"	`Glob` or `Grep -c` directly from the main thread
"Does this tool/agent do X?"	Dispatch one read-only `general-purpose` agent: "Report what `<thing>` actually does, with file:line citations"
"Build is green / artefact exists"	One `Bash` call (`gh pr checks`, `ls path`, `git log --branches`)
"User's bug is X"	Read the failing log; do not patch the symptom
Manifest / counter snapshot	`Read` the file and quote the relevant lines

Inline the verifier if it is one to three tool calls. Use a one-shot investigation agent only when the answer requires multi-file synthesis.

Step 3: Verifier return contract

The verifier — whether inline calls or a dispatched agent — must report:

## Premise
<one-line restatement of what is being checked>

## Evidence
- file:line — <quoted finding>
- file:line — <quoted finding>

## Verdict
- confirmed | refuted | partial: <what changed>
- exact count / value: <N>
- sample paths: <up to 5>

## Implicit assumptions surfaced
- <assumptions the verifier had to make to answer>
- empty is fine — section must exist

Refuse to dispatch the wave until this report exists. "I'll check while dispatching" loses the salvage argument before it starts.

Step 4: Diff verdict against premise

If confirmed, dispatch as planned. If refuted or partial, revise the plan: shrink the file scope, re-allocate per-agent IDs, drop agents that no longer have work, re-write the brief that cites the refuted fact. Only then dispatch.

Anti-patterns

Premise	How it fails	Verifier
"There are 41 SKILL.md files needing edits"	Actual was 28 — some plugins have no skills; 13 agents had empty briefs	`Glob("**/SKILL.md")` then count
"git-repo-agent supports X" (from the name)	Name ≠ behaviour; agent did not implement X	Read `agents/git-repo-agent/SKILL.md`
"The user says the bug is X"	Bug was a config typo two layers up; the X patch did nothing	Read the failing log / repro
"The plan says clear stuck Jobs"	Real root cause was an IdP password mismatch in ConfigMap; jobs were a symptom	Re-spelunk with one read-only agent
"Manifest counter is at WO-012"	Counter was bumped by a coworker mid-session	`Read` the manifest as the last act before allocation
"Build is green" (from morning standup)	Broke an hour ago; one wave-member tripped over the failing step	`gh pr checks` or `gh run list`
"All callers of the deprecated API are gone"	Two remained in a vendored copy outside the search root	`Grep` with a wide-enough path

The unifying pattern: the premise was true at some past moment, but the current session has not confirmed it. Time is the silent invalidator.

Composition

With …	Slot it in by …
`parallel-agent-dispatch`	Verify before the worktree-preflight; preflight assumes the file scope is right
`wave-based-dispatch`	Verify per wave — a Phase-1 wave's return contract is a premise for Phase 2
`exclusive-lock-dispatch`	Verify the lock-holder list is current; locks come and go
`agent-teams`	The Lead Preflight Checklist's "file-scope and pin-budget" entries are premises

Quick Reference

Orchestrator checklist (before any parallel dispatch)

Premise named in one or two sentences with numbers and paths
Verifier picked (inline call ≤ 3, otherwise one read-only agent)
Verifier return contract followed (Premise / Evidence / Verdict / Assumptions)
Verdict confirmed — or plan revised before dispatch
Implicit assumptions logged for the wave's briefs

Common mistakes

Mistake	Correct approach
"Based on the name, X probably does Y"	Dispatch a read-only probe; cite file:line
"The user says the bug is X, so we patch X"	Read the failing repro before any patch
"The plan's remediation is X"	Verify the plan's premise; remediations inherit its truth-value
Verifying after dispatch ("I'll check while they work")	Verify first — re-running a wave costs more than the probe
Skipping the Verdict line — just summarising	The wave's briefs need a copy-pasteable fact, not a narrative

parallel-agent-dispatch — the dispatch contract whose preflight this skill protects
wave-based-dispatch — per-wave premise verification fits cleanly between phases
exclusive-lock-dispatch — lock inventory is itself a premise
.claude/rules/regression-testing.md — landing a verifier as a script check when a premise-failure recurs
Motivating evidence: issue #1283 — aggregate wrong_approach and initial_misdiagnosis signals across 284 sessions

verify-before-plan