ci: diff mutants only on request; the review pipeline proves them on the material before reviewing

Validate ran the three "Мутанты по диффу" shards on every push of every
branch: 48 of 56 job-hours on 08–09.09, most of them cancelled by the
next push. Mutants now run when asked — pull requests, the nightly
schedule, a push carrying a `Release:` trailer, or a dispatch with
`mutants=true` (classify-changes.mjs → `mutants_requested`); an ordinary
push runs the light checks only.

The proof moves to where it is consumed. process.yml gets a gate after
the #499 reuse step: on the code stage it looks for a dispatch Validate
run on the exact material SHA whose mutant jobs executed and passed
(scripts/validate-gate.mjs); none → it dispatches one and waits; red or
missing → the task goes back S7→S6 with the run link and the review
cycle is not spent. Spec stage and the reuse fast-path skip the gate
(`proceed=true`); all later steps branch on `proceed` in place of the
old conflict conjunct only. merge-candidate.mjs dispatches Validate on
the pushed candidate and waits for that dispatch run.

PROCESS.md/AGENTS.md: review does not start on red code; one handoff —
one push.

Mutants: mutants-run-on-every-push, review-starts-on-red-validate,
review-trusts-push-run-without-mutants, merge-waits-push-run-without-mutants.

Issue: #510
User-Visible: no

test/classify-changes.test.mjs

@@ -2,7 +2,7 @@ import test from 'node:test';
 import assert from 'node:assert/strict';
 import { execFileSync } from 'node:child_process';
 import {
-  CHECK_OF_OUTPUT, CLASSIFIERS, OUTPUTS, PERF_PROFILES, classifyAll, classifyChanges, formatOutputs,
+  CHECK_OF_OUTPUT, CLASSIFIERS, OUTPUTS, PERF_PROFILES, classifyAll, classifyChanges, formatOutputs, mutantsRequested,
 } from '../scripts/classify-changes.mjs';
 import { manifest } from '../scripts/check-inputs.mjs';
 import { fileURLToPath } from 'node:url';
@@ -160,7 +160,20 @@ test('CLI --heavy читает событие и сообщение из окр
   const run = (env) => execFileSync(process.execPath, ['scripts/classify-changes.mjs', '--heavy'], {
     encoding: 'utf8', env: { ...process.env, ...env },
   }).trim();
-  assert.equal(run({ EVENT_NAME: 'push', HEAD_MESSAGE: 'fix: x\n\nIssue: #1\nUser-Visible: no' }), 'heavy=false');
-  assert.equal(run({ EVENT_NAME: 'push', HEAD_MESSAGE: 'x\n\nRelease: v1.2.3' }), 'heavy=true');
-  assert.equal(run({ EVENT_NAME: 'workflow_dispatch', FULL_INPUT: 'true', HEAD_MESSAGE: '' }), 'heavy=true');
+  assert.equal(run({ EVENT_NAME: 'push', HEAD_MESSAGE: 'fix: x\n\nIssue: #1\nUser-Visible: no' }), 'heavy=false\nmutants_requested=false');
+  assert.equal(run({ EVENT_NAME: 'push', HEAD_MESSAGE: 'x\n\nRelease: v1.2.3' }), 'heavy=true\nmutants_requested=true');
+  assert.equal(run({ EVENT_NAME: 'workflow_dispatch', FULL_INPUT: 'true', HEAD_MESSAGE: '' }), 'heavy=true\nmutants_requested=true');
+  // #510: мутанты по кнопке без полного набора — вызов конвейера ревью и слияния
+  assert.equal(run({ EVENT_NAME: 'workflow_dispatch', FULL_INPUT: 'false', MUTANTS_INPUT: 'true', HEAD_MESSAGE: '' }), 'heavy=false\nmutants_requested=true');
+});
+
+test('#510 AC1: мутанты по диффу запрашиваются кандидатом, PR, ночью и по кнопке — не обычным пушем', () => {
+  const t = (env) => mutantsRequested(env);
+  assert.equal(t({ eventName: 'push', headMessage: 'fix: x\n\nIssue: #1\nUser-Visible: no' }), false, 'обычный push');
+  assert.equal(t({ eventName: 'push', headMessage: 'x\n\nRelease: v1.2.3' }), true, 'кандидат беты');
+  assert.equal(t({ eventName: 'pull_request' }), true);
+  assert.equal(t({ eventName: 'schedule' }), true);
+  assert.equal(t({ eventName: 'workflow_dispatch', fullInput: 'true' }), true);
+  assert.equal(t({ eventName: 'workflow_dispatch', fullInput: 'false', mutantsInput: 'true' }), true);
+  assert.equal(t({ eventName: 'workflow_dispatch', fullInput: 'false', mutantsInput: 'false' }), false, 'кнопка без запроса');
 });