diff --git a/docs/jev.md b/docs/jev.md
new file mode 100644
index 00000000..02fc5187
--- /dev/null
+++ b/docs/jev.md
@@ -0,0 +1,159 @@
+# Jev without another runtime
+
+Jev belongs in a bounded decision, judge, or analyst callback. Runtime already owns
+execution, graph scheduling, continuation, journals, and budgets. Do not add a
+`JevAgent`, a second graph runner, or another critique/revise loop.
+
+## Graphs: use the existing registry adapter
+
+After the Eval change that publishes `@tangle-network/agent-eval/jev`, construct an
+ordinary `jevAnalyst` and register it in the existing Eval registry. Then use
+`analystsFromRegistry` to attach it to an `analyzes` edge. The application owns the
+scoped native transport, trace selection/redaction, findings, and paid-call account.
+
+```ts
+import { AnalystRegistry } from '@tangle-network/agent-eval/analyst'
+import { jevAnalyst } from '@tangle-network/agent-eval/jev'
+import {
+  analystsFromRegistry,
+  promptHandle,
+  runGraph,
+} from '@tangle-network/agent-runtime/kernel'
+
+const registry = new AnalystRegistry({
+  hooks: {
+    // Retain failed/skipped summaries and usage, not only the returned findings.
+    onAfterAnalyze: persistAnalystSummary,
+  },
+})
+
+registry.register(jevAnalyst({
+  id: 'evidence-review',
+  description: 'Assess supplied execution evidence against the task requirements',
+  inputKind: 'trace-store',
+  model: pinnedJevModel,
+  version: policyVersion,
+  questions: reviewQuestions,
+  evaluate: nativeEvaluation, // Router /v1/systemone; single accounted attempt.
+  renderState: renderAuthorizedTraceEvidence,
+  findings: mapAnswersToEvidenceBackedFindings,
+  maximumCharge: enforcedMaximumCharge,
+  receipt: readNativeReceipt,
+}))
+
+const graph = {
+  nodes: [
+    { id: 'driver', profile: driverProfile },
+    { id: 'worker', profile: workerProfile },
+  ],
+  edges: [
+    {
+      kind: 'delegates' as const,
+      from: 'driver', to: 'worker',
+      directive: promptHandle('delegates/worker-brief/v1'),
+      continuity: 'resume' as const,
+      maxTraversals: authorizedTraversalLimit,
+    },
+    {
+      kind: 'analyzes' as const,
+      analyst: 'evidence-review', over: ['worker'], to: 'driver',
+      directive: promptHandle('analyzes/findings-report/v1'),
+    },
+  ],
+  budget: authorizedBudget,
+  deliverable: independentCompletionCheck,
+}
+
+const result = await runGraph(graph, {
+  ...executionOptions,
+  analysts: analystsFromRegistry(registry, [{
+    id: 'evidence-review', description: 'Review execution evidence', area: 'verification',
+  }], { runOpts: {
+    signal,
+    costLedger: sharedCostLedger,
+    costPhase: 'graph-review',
+  } }),
+})
+```
+
+The named values above are caller-owned domain/execution configuration, not hidden
+defaults. Use real span/event/artifact references in findings. A probability-like
+answer is a model judgment, not a causal diagnosis or a demonstrated calibration.
+Do not reveal final-test rubrics to workers through review feedback.
+
+`runGraph` keeps node pinning, versioned directives, traversal caps, resume semantics,
+and edge-delivery evidence. A function-shaped analyst does not become free: its
+native call must use the shared paid-call ledger with a genuine enforced bound.
+Do not assume a separate analyst ledger automatically debits the Supervisor's token
+pool. Allocate explicit analyst authority and reconcile its receipts in the total
+experiment account; where one Supervisor pool must own every call, use the existing
+metered agent-analyst path rather than hiding inference inside a supposedly pure lens.
+
+The registry isolates analyst failures; its findings list alone is not proof of a
+successful analysis. Persist and inspect the existing summaries. A failed optional
+review must not be interpreted as a clean bill of health or an authorization to act.
+
+## Before and after local inference
+
+Use the actual call boundaries, not a new hook bus:
+
+- `ToolLoopHooks.beforeTurn` is awaited and can prepare the conversation. It runs
+  **before** the existing compaction step.
+- `ToolLoopCompaction.distill` owns compaction at a clean tool-call boundary. Do not
+  add a second compactor or orphan tool requests from their results.
+- A caller-owned `ToolLoopChat` can prepare the final outgoing request and inspect
+  the completed result. Preserve the provided signal, call/correlation identity,
+  tool grants, served-model evidence, and all physical-attempt receipts.
+- `RuntimeHooks` is observation-only. Its notifier does not await a required model
+  decision and deliberately isolates observer errors. Use a durable sink/queue for
+  analysis that must survive coordinator termination.
+
+A normal awaited composition is enough:
+
+```ts
+const brain: ToolLoopChat = async (messages, tools, context) => {
+  context?.signal.throwIfAborted()
+  const prepared = await prepareAllowedContext(messages, context)
+  context?.signal.throwIfAborted()
+  const response = await modelCall(prepared, tools, context)
+  await inspectCompletedResponse(response, context)
+  return response
+}
+```
+
+This is an ordering example, not a complete metering wrapper. When preparation or
+inspection calls Jev, admit those calls through the shared paid-call account and
+preserve their receipts even if a later operation fails. Do not return only the
+main model's usage and call the entire program measured. Do not hide paid work in
+an observer. Optional optimization failures should preserve the ordinary agent path;
+authorization and irreversible actions remain deterministic controls.
+
+A blocking output policy must run before delivery. It cannot retract streamed text
+or undo completed tool effects. Prefer explicit generation → evaluation → revision
+composition over silently rewriting a user's answer after it has been delivered.
+
+## Sandbox coverage
+
+A sandbox prompt may contain many native model requests. Session preparation is not
+a portable barrier before each request inside Claude Code, Codex, or another external
+harness. Use the substrate's supported native hooks and document their actual scope.
+Do not add a misleading universal `beforeInference` flag to `agent-provider-tangle`.
+
+## Optimization
+
+The new Eval judge returns the existing `JudgeConfig`, so current campaigns and
+`improve()` remain the path for comparing prompt variants, questions, rubric levels,
+context policies, and output-selection policies. Keep train, selection, and final-test
+partitions separate, and retain exact candidate/model versions plus all inner costs.
+Jev selects/evaluates bounded options; generative models still produce arbitrary
+arguments, code, summaries, and prompt rewrites.
+
+## Verification and dependencies
+
+`tests/kernel/jev-composition.test.ts` exercises the existing registry/graph and local
+call ordering with deterministic injected responses. It is not a live Jev benchmark.
+No new Runtime dependency or public orchestration primitive is needed. Production
+consumers need the released Eval adapter and the native Router endpoint; do not
+claim support merely because an unpublished import appears in a snippet.
+
+Related changes: agent-eval #761, tangle-router #531, agent-dev-container #7620.
diff --git a/src/runtime/supervise-surface.ts b/src/runtime/supervise-surface.ts
index 23e02831..f2ef7d65 100644
--- a/src/runtime/supervise-surface.ts
+++ b/src/runtime/supervise-surface.ts
@@ -162,6 +162,13 @@ export function analystsFromRegistry(
         { traceStore: trace },
         { ...opts?.runOpts, only: [kindId] },
       )
+      // Registry failures are isolated, not successful reviews with zero findings.
+      const summary = result.per_analyst.find((entry) => entry.analyst_id === kindId)
+      if (summary?.status !== 'ok') {
+        throw new ValidationError(
+          `analyst ${JSON.stringify(kindId)} did not complete: ${summary?.status ?? 'missing result'}`,
+        )
+      }
       return result.findings
     },
     ...(authoring === undefined
@@ -218,7 +225,7 @@ export interface AnalystAuthoring {
  *
  * The version is DERIVED from the definition's own canonical digest, never supplied by the manager.
  * That is what makes an invented lens reproducible: the same authored words always compile to the
- * same analyst version, two different wordings can never share one, and a finding's `analyst_id`
+ * same version, two different wordings can never share one, and a finding's `analyst_id`
  * plus version names the exact text that produced it.
  */
 function traceAnalystFromAuthored(definition: AuthoredAnalystDefinition): TraceAnalystDefinition {
diff --git a/src/runtime/tool-loop.ts b/src/runtime/tool-loop.ts
index b6f2fd7d..447bd1e0 100644
--- a/src/runtime/tool-loop.ts
+++ b/src/runtime/tool-loop.ts
@@ -64,7 +64,7 @@ export type ToolLoopChat = (
 export interface ToolLoopHooks {
   /** Run before each inference turn (e.g. flush queued steers into `messages`). */
   beforeTurn?(turn: number, messages: ToolLoopMessageRecord[]): void | Promise<void>
-  /** Return true to stop before the next turn (e.g. pool starved / deadline passed / aborted). */
+  /** Stop predicate, rechecked after awaited preparation before spending on inference. */
   stopBefore?(turn: number): boolean
   /** Each turn's usage, for metering into a conserved budget pool. */
   onUsage?(usage: { input: number; output: number }): void
@@ -206,10 +206,15 @@ export async function runBrainLoop(opts: {
   for (let turn = 1; maxTurns === 0 || turn <= maxTurns; turn += 1) {
     if (opts.hooks?.stopBefore?.(turn)) break
     await opts.hooks?.beforeTurn?.(turn, messages)
+    // Preparation may run a classifier or await a steer while authority changes.
+    if (opts.hooks?.stopBefore?.(turn)) break
     // Close the chapter BEFORE the inference turn that would otherwise re-bill the whole transcript:
     // distill the accumulated middle to a compact note so this and every later turn pay O(working-set),
     // not O(total-history). A clean boundary — the prior turn's tool replies are already folded in.
-    if (opts.compaction) await maybeCompact(messages, opts.compaction, turn)
+    if (opts.compaction) {
+      await maybeCompact(messages, opts.compaction, turn)
+      if (opts.hooks?.stopBefore?.(turn)) break
+    }
     const r = await opts.chat(messages, opts.tools)
     completedTurns = turn
     if (r.usage) {
diff --git a/tests/kernel/jev-composition.test.ts b/tests/kernel/jev-composition.test.ts
new file mode 100644
index 00000000..040b287a
--- /dev/null
+++ b/tests/kernel/jev-composition.test.ts
@@ -0,0 +1,121 @@
+import { type AnalystContext, CostLedger } from '@tangle-network/agent-eval'
+import { AnalystRegistry } from '@tangle-network/agent-eval/analyst'
+import { describe, expect, it } from 'vitest'
+import { shotLoop } from '../../examples/graphs/shot-loop'
+import { analystsFromRegistry } from '../../src/runtime/supervise-surface'
+import { runBrainLoop } from '../../src/runtime/tool-loop'
+import { runGraphWithTestBrain } from '../../src/testing'
+
+// These are composition proofs over deterministic fixtures, not live Jev quality tests.
+describe('native decision composition without another runtime', () => {
+  it('delivers an ordinary Eval analyst through the existing graph and ledger', async () => {
+    const contexts: AnalystContext[] = []
+    const registry = new AnalystRegistry()
+    const sharedCostLedger = new CostLedger()
+    const controller = new AbortController()
+    registry.register({
+      id: 'verify',
+      description: 'Fixture for a native evidence-review analyst',
+      inputKind: 'trace-store',
+      version: 'native-fixture-v1',
+      // No network or real model runs in this fixture.
+      cost: { kind: 'deterministic' },
+      async analyze(store, context) {
+        expect(store).toBeDefined()
+        contexts.push(context)
+        const answer = { type: 'noul', noul: 0.75 } as const
+        return [
+          {
+            schema_version: '1.0.0',
+            finding_id: `fixture-${context.runId}`,
+            analyst_id: 'verify',
+            produced_at: new Date(0).toISOString(),
+            severity: 'info',
+            area: 'verification',
+            claim: 'Injected native-answer fixture reached the graph reviewer',
+            confidence: answer.noul,
+            evidence_refs: [],
+            derived_from_judge: true,
+            metadata: { fixture: true, nativeAnswer: answer },
+          },
+        ]
+      },
+    })
+    const { graph, opts } = shotLoop()
+    const analysts = analystsFromRegistry(
+      registry,
+      [
+        {
+          id: 'verify',
+          description: 'Native-answer fixture',
+          area: 'verification',
+        },
+      ],
+      {
+        runOpts: {
+          signal: controller.signal,
+          costLedger: sharedCostLedger,
+          costPhase: 'graph-review',
+          tags: { policy: 'native-fixture-v1' },
+        },
+      },
+    )
+    const result = await runGraphWithTestBrain(graph, {
+      ...opts,
+      runId: 'jev-composition-fixture',
+      analysts,
+    })
+    expect(contexts.length).toBeGreaterThan(0)
+    expect(contexts.every((context) => context.costLedger === sharedCostLedger)).toBe(true)
+    expect(contexts.every((context) => context.costPhase === 'graph-review')).toBe(true)
+    expect(contexts.every((context) => context.tags?.policy === 'native-fixture-v1')).toBe(true)
+    expect(result.ledger.some((edge) => edge.kind === 'analyzes')).toBe(true)
+    expect(result.ledger.some((edge) => edge.edge === 'analyzes:verify:coder->reviewer')).toBe(true)
+    expect(graph.nodes.map((node) => node.id)).toEqual(['reviewer', 'coder'])
+  })
+
+  it('prepares before compaction and observes the exact post-compaction request', async () => {
+    const order: string[] = []
+    const result = await runBrainLoop({
+      initialMessages: [
+        { role: 'system', content: 'Keep mandatory instructions.' },
+        { role: 'user', content: 'Original task.' },
+        { role: 'assistant', content: 'Prior work.' },
+      ],
+      tools: [],
+      maxTurns: 1,
+      hooks: {
+        async beforeTurn(_turn, messages) {
+          order.push('prepare')
+          messages.push({ role: 'user', content: 'Selected optional context.' })
+        },
+      },
+      compaction: {
+        thresholdTokens: 1,
+        preserveHead: 2,
+        distill: async () => {
+          order.push('compact')
+          return 'Retained progress.'
+        },
+      },
+      chat: async (messages) => {
+        order.push('inference')
+        expect(messages[0]?.content).toBe('Keep mandatory instructions.')
+        expect(messages[1]?.content).toBe('Original task.')
+        expect(messages.at(-1)?.content).toContain('Retained progress.')
+        const response = { content: 'answer', toolCalls: [], usage: { input: 10, output: 2 } }
+        // Awaited caller composition, not RuntimeHooks or a second loop.
+        await Promise.resolve().then(() => {
+          order.push('inspect')
+        })
+        return response
+      },
+      execute: async () => {
+        throw new Error('No tool should execute')
+      },
+    })
+    expect(order).toEqual(['prepare', 'compact', 'inference', 'inspect'])
+    expect(result.final).toBe('answer')
+    expect(result.usage).toEqual({ input: 10, output: 2 })
+  })
+})
diff --git a/tests/kernel/supervise-surface.test.ts b/tests/kernel/supervise-surface.test.ts
index 21832d16..dda5bef7 100644
--- a/tests/kernel/supervise-surface.test.ts
+++ b/tests/kernel/supervise-surface.test.ts
@@ -171,7 +171,10 @@ describe('analystsFromRegistry — the eval registry as a supervise lens', () =>
       list: () => DEFAULT_TRACE_ANALYST_KINDS.map((kind) => ({ id: kind.id })),
       run: async (runId, inputs, opts) => {
         calls.push({ runId, only: opts?.only, hasStore: inputs.traceStore !== undefined })
-        return { findings: [finding] } as never
+        return {
+          findings: [finding],
+          per_analyst: [{ analyst_id: opts?.only?.[0], status: 'ok' }],
+        } as never
       },
     }
   }
@@ -198,6 +201,41 @@ describe('analystsFromRegistry — the eval registry as a supervise lens', () =>
     expect(registry.calls[0]?.hasStore).toBe(true)
   })
 
+  it.each(['failed', 'skipped'] as const)(
+    'does not report a %s analyst as a clean review',
+    async (status) => {
+      const registry = fakeRegistry()
+      registry.run = async () =>
+        ({
+          findings: [],
+          per_analyst: [{ analyst_id: 'failure-mode', status }],
+        }) as never
+      await expect(
+        analystsFromRegistry(registry).run('failure-mode', toolSpansToTraceAnalysisStore([span])),
+      ).rejects.toThrow(`did not complete: ${status}`)
+    },
+  )
+
+  it('refuses a missing execution receipt even when there are no findings', async () => {
+    const registry = fakeRegistry()
+    registry.run = async () => ({ findings: [], per_analyst: [] }) as never
+    await expect(
+      analystsFromRegistry(registry).run('failure-mode', toolSpansToTraceAnalysisStore([span])),
+    ).rejects.toThrow('missing result')
+  })
+
+  it('preserves a successful review with no findings', async () => {
+    const registry = fakeRegistry()
+    registry.run = async () =>
+      ({
+        findings: [],
+        per_analyst: [{ analyst_id: 'failure-mode', status: 'ok' }],
+      }) as never
+    await expect(
+      analystsFromRegistry(registry).run('failure-mode', toolSpansToTraceAnalysisStore([span])),
+    ).resolves.toEqual([])
+  })
+
   it('refuses a kind the registry does not have, at adapt time', () => {
     expect(() =>
       analystsFromRegistry(fakeRegistry(), [
diff --git a/tests/kernel/tool-loop-preparation-stop.test.ts b/tests/kernel/tool-loop-preparation-stop.test.ts
new file mode 100644
index 00000000..21461bee
--- /dev/null
+++ b/tests/kernel/tool-loop-preparation-stop.test.ts
@@ -0,0 +1,109 @@
+import { describe, expect, it, vi } from 'vitest'
+import { runBrainLoop } from '../../src/runtime/tool-loop'
+
+const initialMessages = [
+  { role: 'system', content: 'Keep the task constraints.' },
+  { role: 'user', content: 'Complete the task.' },
+  { role: 'assistant', content: 'Earlier work.' },
+  { role: 'user', content: 'More evidence.' },
+]
+
+const response = {
+  content: 'done',
+  toolCalls: [],
+  usage: { input: 10, output: 2 },
+}
+
+describe('tool-loop preparation authority', () => {
+  it('does not compact or infer after cancellation during a classifier hook', async () => {
+    const controller = new AbortController()
+    const chat = vi.fn(async () => response)
+    const distill = vi.fn(async () => 'digest')
+    const execute = vi.fn(async () => 'tool output')
+    const result = await runBrainLoop({
+      initialMessages,
+      chat,
+      tools: [],
+      execute,
+      hooks: {
+        stopBefore: () => controller.signal.aborted,
+        beforeTurn: async (_turn, messages) => {
+          await Promise.resolve()
+          messages.push({ role: 'user', content: 'Classifier observation retained.' })
+          controller.abort()
+        },
+      },
+      compaction: { thresholdTokens: 1, distill },
+    })
+    expect(chat).not.toHaveBeenCalled()
+    expect(distill).not.toHaveBeenCalled()
+    expect(execute).not.toHaveBeenCalled()
+    expect(result.turns).toBe(0)
+    expect(result.usage).toEqual({ input: 0, output: 0 })
+    expect(result.messages.at(-1)?.content).toBe('Classifier observation retained.')
+  })
+
+  it('does not infer when compaction consumes the remaining execution budget', async () => {
+    let budgetAvailable = true
+    const chat = vi.fn(async () => response)
+    const onCompact = vi.fn()
+    const result = await runBrainLoop({
+      initialMessages,
+      chat,
+      tools: [],
+      execute: async () => 'unused',
+      hooks: { stopBefore: () => !budgetAvailable },
+      compaction: {
+        thresholdTokens: 1,
+        distill: async () => {
+          await Promise.resolve()
+          budgetAvailable = false
+          return 'Completed compaction retained for resume.'
+        },
+        onCompact,
+      },
+    })
+    expect(chat).not.toHaveBeenCalled()
+    expect(onCompact).toHaveBeenCalledOnce()
+    expect(result.turns).toBe(0)
+    expect(result.messages.at(-1)?.content).toContain('Completed compaction retained for resume.')
+    expect(result.messages.slice(0, 2)).toEqual(initialMessages.slice(0, 2))
+  })
+
+  it('retains completed turns, tool results, and metering when a later hook stops the run', async () => {
+    let stopped = false
+    const onUsage = vi.fn()
+    const chat = vi.fn(async () => ({
+      content: 'Check the evidence.',
+      toolCalls: [{ id: 'tool-1', name: 'read', arguments: '{}' }],
+      usage: { input: 10, output: 2 },
+    }))
+    const execute = vi.fn(async () => 'Observed evidence.')
+    const result = await runBrainLoop({
+      initialMessages: initialMessages.slice(0, 2),
+      tools: [],
+      maxTurns: 0,
+      chat,
+      execute,
+      hooks: {
+        stopBefore: () => stopped,
+        beforeTurn: async (turn) => {
+          await Promise.resolve()
+          if (turn === 2) stopped = true
+        },
+        onUsage,
+      },
+    })
+    expect(chat).toHaveBeenCalledOnce()
+    expect(execute).toHaveBeenCalledOnce()
+    expect(onUsage).toHaveBeenCalledExactlyOnceWith({ input: 10, output: 2 })
+    expect(result.turns).toBe(1)
+    expect(result.toolCalls).toBe(1)
+    expect(result.usage).toEqual({ input: 10, output: 2 })
+    expect(result.messages.at(-1)).toEqual({
+      role: 'tool',
+      tool_call_id: 'tool-1',
+      content: 'Observed evidence.',
+    })
+  })
+})