From 59a2ab3d232236af2c6d2162482ff518c3cd6968 Mon Sep 17 00:00:00 2001
From: Miya <khaliqgant+miya@gmail.com>
Date: Tue, 15 Sep 2026 18:54:08 +0200
Subject: [PATCH 1/3] fix(sdk): default Claude steps to Sonnet 4.6

Session-Id: 01a09c40-ce3b-7f11-a7df-b6b7ccab6fd9
---
 packages/sdk/src/adapters/base.ts             |  3 ++
 packages/sdk/src/adapters/claude.ts           |  1 +
 packages/sdk/src/budget-preflight.ts          | 16 +++++--
 packages/sdk/src/cli-adapter.ts               |  6 +++
 packages/sdk/src/cli/check.ts                 |  5 ++-
 packages/sdk/src/llm-worker.ts                |  6 ++-
 packages/sdk/src/preflight.ts                 | 45 ++++++++++++-------
 packages/sdk/src/worker-cli.ts                | 12 ++---
 packages/sdk/src/worker.ts                    |  6 ++-
 packages/sdk/tests/adapters/claude.test.ts    |  1 +
 packages/sdk/tests/budget-preflight.test.ts   | 17 +++++--
 packages/sdk/tests/cli-adapter.test.ts        |  7 +++
 .../sdk/tests/flow-executor-chain.test.ts     | 40 ++++++++++++++++-
 packages/sdk/tests/pty-sidechannel.test.ts    |  8 ++--
 packages/sdk/tests/worker-cli.test.ts         | 23 ++++++++++
 15 files changed, 159 insertions(+), 37 deletions(-)

diff --git a/packages/sdk/src/adapters/base.ts b/packages/sdk/src/adapters/base.ts
index a6daaddd7..da0d1da38 100644
--- a/packages/sdk/src/adapters/base.ts
+++ b/packages/sdk/src/adapters/base.ts
@@ -32,6 +32,9 @@ export interface HeadlessAdapter {
   /** Identity of this adapter — matches CliAdapterKind for registry keys. */
   readonly kind: string;
 
+  /** Stable model used when an author omits one. */
+  readonly defaultModel?: string;
+
   /** Shape-check invocation before classifying an auth failure. */
   buildIdentification(): CliAdapterIdentification;
 
diff --git a/packages/sdk/src/adapters/claude.ts b/packages/sdk/src/adapters/claude.ts
index 8d163118a..187d4c9c6 100644
--- a/packages/sdk/src/adapters/claude.ts
+++ b/packages/sdk/src/adapters/claude.ts
@@ -10,6 +10,7 @@ const MODEL_PROBE_PROMPT = 'Reply with exactly RELAYFLOWS_MODEL_READY and nothin
  *  pre-#141 inline shape in `cli-adapter.ts` — only the packaging changed. */
 export const claudeAdapter: HeadlessAdapter = {
   kind: 'claude',
+  defaultModel: 'claude-sonnet-4-6',
 
   buildIdentification(): CliAdapterIdentification {
     return { invocation: { args: ['auth', 'status', '--help'], timeoutMs: 10_000 } };
diff --git a/packages/sdk/src/budget-preflight.ts b/packages/sdk/src/budget-preflight.ts
index 449f14633..319c77fc9 100644
--- a/packages/sdk/src/budget-preflight.ts
+++ b/packages/sdk/src/budget-preflight.ts
@@ -3,7 +3,10 @@ import type { PreflightRefusal } from './preflight.js';
 import { MODEL_PRICING } from './model-pricing.js';
 
 /** Legacy explicit envelopes keep their worker-supplied pricing contract. */
-export function budgetDiagnostics(flow: CompiledFlowSpec): PreflightRefusal[] {
+export function budgetDiagnostics(
+  flow: CompiledFlowSpec,
+  resolvedModels: ReadonlyMap<string, string | undefined> = new Map(),
+): PreflightRefusal[] {
   if (flow.budget?.pricing !== 'frozen') return [];
   const diagnostics: PreflightRefusal[] = [];
   const declared = [
@@ -13,12 +16,19 @@ export function budgetDiagnostics(flow: CompiledFlowSpec): PreflightRefusal[] {
   ];
   for (const step of flow.steps) {
     if (step.type === 'deterministic' || flow.budget.maxDollars === undefined) continue;
-    const model = step.model ?? (step.type === 'agent' && step.agent !== undefined
-      ? flow.agents?.[step.agent]?.model : undefined);
+    const model = resolvedModels.has(step.id) ? resolvedModels.get(step.id)
+      : step.model ?? (step.type === 'agent' && step.agent !== undefined
+        ? flow.agents?.[step.agent]?.model : undefined);
     if (model === undefined) diagnostics.push({
       severity: 'refusal', kind: 'budget_missing_price', stepId: step.id,
       message: `Step "${step.id}" needs a declared, priced model for its dollar budget.`,
     });
+    else if (step.model === undefined
+      && (step.type !== 'agent' || step.agent === undefined || flow.agents?.[step.agent]?.model === undefined)
+      && !Object.hasOwn(MODEL_PRICING, model)) diagnostics.push({
+      severity: 'refusal', kind: 'budget_missing_price', stepId: step.id, model,
+      message: `Model "${model}" has no frozen price for budget accounting.`,
+    });
   }
   for (const declaration of declared) {
     if (Object.hasOwn(MODEL_PRICING, declaration.model)) continue;
diff --git a/packages/sdk/src/cli-adapter.ts b/packages/sdk/src/cli-adapter.ts
index 0133c552d..a7ac82e2b 100644
--- a/packages/sdk/src/cli-adapter.ts
+++ b/packages/sdk/src/cli-adapter.ts
@@ -28,6 +28,12 @@ export function cliAdapterKind(executable: string): CliAdapterKind {
   return resolveAdapterKind(executable);
 }
 
+/** Resolve only defaults owned by registered raw-CLI adapters. */
+export function resolveCliModel(executable: string, model?: string): string | undefined {
+  if (model !== undefined) return model;
+  return registeredAdapters()[resolveAdapterKind(executable)].defaultModel;
+}
+
 /** Prove the adapter command shape before classifying an auth failure. */
 export function adapterIdentification(kind: CliAdapterKind): CliAdapterIdentification {
   return registeredAdapters()[kind].buildIdentification();
diff --git a/packages/sdk/src/cli/check.ts b/packages/sdk/src/cli/check.ts
index b96e435c4..f9f56d81d 100644
--- a/packages/sdk/src/cli/check.ts
+++ b/packages/sdk/src/cli/check.ts
@@ -358,7 +358,10 @@ function bindResolvedCliPaths(
       const resolution = byStep.get(step.id);
       if (resolution === undefined) return step;
       const directory = resolution.source === 'project' ? configDirectory : flowDirectory;
-      return { ...step, cli: canonicalCli(resolution.cli, directory) };
+      const declaredModel = step.model ?? (step.type === 'agent' && step.agent !== undefined
+        ? flow.agents?.[step.agent]?.model : undefined);
+      return { ...step, cli: canonicalCli(resolution.cli, directory),
+        ...(declaredModel === undefined && resolution.model !== undefined ? { model: resolution.model } : {}) };
     }),
   };
 }
diff --git a/packages/sdk/src/llm-worker.ts b/packages/sdk/src/llm-worker.ts
index b004b947d..cf4002b97 100644
--- a/packages/sdk/src/llm-worker.ts
+++ b/packages/sdk/src/llm-worker.ts
@@ -5,6 +5,7 @@ import type { JournalClient } from './journal-client.js';
 import type { CompletionReason, StepDispatchEvent } from './protocol.js';
 import type { KernelLlmStep } from './spec.js';
 import { runAgentCli } from './worker-cli.js';
+import { resolveCliModel } from './cli-adapter.js';
 import { withWorkerLease } from './worker-lease.js';
 import { workerInstruction } from './worker-input.js';
 import { jsonSchemaOutputError } from './json-schema.js';
@@ -49,11 +50,12 @@ export class LlmWorker extends EventEmitter {
     const schema = spec.verification?.json_schema;
     const prompt = schema === undefined ? spec.prompt
       : `${spec.prompt}\n\nReturn only a JSON value matching this JSON Schema (no Markdown fences):\n${JSON.stringify(schema)}`;
+    const effectiveModel = typeof spec.cli === 'string' ? resolveCliModel(spec.cli, spec.model) : spec.model;
     const completed: WorkerCliResult = await withWorkerLease(this.client, dispatch, signal =>
       typeof spec.cli === 'string' && typeof spec.prompt === 'string'
-        ? runAgentCli(spec.cli, workerInstruction(prompt, dispatch), dispatch.wake_context, spec.model, undefined, signal, 'llm')
+        ? runAgentCli(spec.cli, workerInstruction(prompt, dispatch), dispatch.wake_context, effectiveModel, undefined, signal, 'llm')
         : Promise.resolve({ exit_code: null, stdout_tail: '', stderr_tail: 'llm step has no declared CLI' }));
-    const { result, usage } = workerSpend(completed, spec.model);
+    const { result, usage } = workerSpend(completed, effectiveModel);
     let reason: CompletionReason = result.exit_code === 0 ? 'success' : 'worker_error';
     let output: unknown = result.stdout_tail;
     let detail = result.stderr_tail;
diff --git a/packages/sdk/src/preflight.ts b/packages/sdk/src/preflight.ts
index 6043c8274..f42a37acd 100644
--- a/packages/sdk/src/preflight.ts
+++ b/packages/sdk/src/preflight.ts
@@ -8,6 +8,7 @@ import type { TriggerSource } from '@relayflows/surface';
 import { acceptsAnyOutput, inspectStepGate, type StepGateInspection } from './gate-contract.js';
 import { compileSpec, CompileError } from './compile.js';
 import { helperCall } from './yaml-helpers.js';
+import { resolveCliModel } from './cli-adapter.js';
 import { isNamedGate, NAMED_GATE_FAILURE_KINDS, type NamedGateFailureKind } from './named-gates.js';
 import { compileScopes, type ScopeInput, type MountRegistry } from './scope-compiler.js';
 import { readMountRegistry } from './mount-registry.js';
@@ -208,18 +209,17 @@ function preflightSync(flow: unknown, options: PreflightOptions): PreflightResul
     };
   }
   const diagnostics: PreflightDiagnostic[] = [];
+  const cliResolutionDiagnostics: PreflightDiagnostic[] = [];
   const resolutions: CliResolution[] = [];
   const resolutionByStep = new Map<string, CliResolution>();
   const cliProbeResults = new Map<string, CliProbeOutcome>();
 
-  diagnostics.push(...unknownModelDiagnostics(compiled, options));
   diagnostics.push(...scopeDiagnostics(compiled, options));
   for (const server of new Set(options.mcpServers ?? [])) {
     if (options.mcp !== undefined && Object.hasOwn(options.mcp, server)) continue;
     diagnostics.push({ severity: 'refusal', kind: 'mcp_undeclared_server', server,
       message: `MCP server "${server}" is not declared in the nearest flows.json mcp map.` });
   }
-  diagnostics.push(...budgetDiagnostics(compiled));
   // Resolve the complete flow before touching any environment fact. A later
   // statically unresolved CLI makes the whole submission impossible, so no
   // earlier command, provider/model, or trigger probe may run first.
@@ -228,7 +228,7 @@ function preflightSync(flow: unknown, options: PreflightOptions): PreflightResul
     if (step.type === 'agent' && helperCall(step) !== undefined) continue;
     const resolution = resolveCli(step, compiled, options.projectCli);
     if (resolution === undefined) {
-      diagnostics.push({
+      cliResolutionDiagnostics.push({
         severity: 'refusal',
         kind: 'cli_unresolved',
         stepId: step.id,
@@ -239,6 +239,12 @@ function preflightSync(flow: unknown, options: PreflightOptions): PreflightResul
       resolutionByStep.set(step.id, resolution);
     }
   }
+  diagnostics.push(...unknownModelDiagnostics(compiled, options, resolutionByStep));
+  diagnostics.push(...cliResolutionDiagnostics);
+  diagnostics.push(...budgetDiagnostics(
+    compiled,
+    new Map(resolutions.map(resolution => [resolution.stepId, resolution.model])),
+  ));
   if (diagnostics.length > 0) {
     return { ok: false, gates: compiled.steps.map(inspectStepGate), resolutions, diagnostics };
   }
@@ -311,6 +317,7 @@ function scopeDiagnostics(flow: FlowSpec, options: PreflightOptions): PreflightR
 function unknownModelDiagnostics(
   flow: FlowSpec,
   options: PreflightOptions,
+  resolutionByStep: ReadonlyMap<string, CliResolution> = new Map(),
 ): PreflightRefusal[] {
   const diagnostics: PreflightRefusal[] = [];
   // model_unknown is a governance check: it exists to enforce a project's
@@ -340,17 +347,21 @@ function unknownModelDiagnostics(
   }
 
   for (const step of flow.steps) {
-    if (step.type === 'deterministic' || step.model === undefined) continue;
-    if (isKnownModel(step.model, options.models)) continue;
+    if (step.type === 'deterministic') continue;
+    const named = step.type === 'agent' && step.agent !== undefined
+      ? flow.agents?.[step.agent] : undefined;
+    if (step.model === undefined && named !== undefined) continue;
+    const resolution = resolutionByStep.get(step.id);
+    const model = step.model ?? resolution?.model;
+    if (model === undefined || isKnownModel(model, options.models)) continue;
     if (!enforceRegistry) continue;
-    const resolution = resolveCli(step, flow, options.projectCli);
     diagnostics.push({
       severity: 'refusal',
       kind: 'model_unknown',
       stepId: step.id,
       ...(resolution === undefined ? {} : { cli: resolution.cli }),
-      model: step.model,
-      message: unknownModelMessage(step.id, step.model, resolution?.cli, options.modelRegistryPath),
+      model,
+      message: unknownModelMessage(step.id, model, resolution?.cli, options.modelRegistryPath),
     });
   }
 
@@ -403,14 +414,16 @@ function resolveCli(
   const named = step.type === 'agent' && step.agent !== undefined
     ? flow.agents?.[step.agent]
     : undefined;
-  // Model comes only from the step or its explicitly selected declaration.
-  // There is deliberately no flow/project or host default.
-  const effectiveModel = step.model ?? named?.model;
-  const model = effectiveModel !== undefined ? { model: effectiveModel } : {};
-  if (step.cli !== undefined) return { stepId: step.id, cli: step.cli, source: 'step', ...model };
-  if (named !== undefined) return { stepId: step.id, cli: named.cli, source: 'named', ...model };
-  if (flow.cli !== undefined) return { stepId: step.id, cli: flow.cli, source: 'flow', ...model };
-  if (projectCli !== undefined) return { stepId: step.id, cli: projectCli, source: 'project', ...model };
+  const declaredModel = step.model ?? named?.model;
+  const resolved = (cli: string, source: CliResolutionSource): CliResolution => {
+    const effectiveModel = resolveCliModel(cli, declaredModel);
+    return { stepId: step.id, cli, source,
+      ...(effectiveModel === undefined ? {} : { model: effectiveModel }) };
+  };
+  if (step.cli !== undefined) return resolved(step.cli, 'step');
+  if (named !== undefined) return resolved(named.cli, 'named');
+  if (flow.cli !== undefined) return resolved(flow.cli, 'flow');
+  if (projectCli !== undefined) return resolved(projectCli, 'project');
   return undefined;
 }
 
diff --git a/packages/sdk/src/worker-cli.ts b/packages/sdk/src/worker-cli.ts
index 8297e1108..0752964e2 100644
--- a/packages/sdk/src/worker-cli.ts
+++ b/packages/sdk/src/worker-cli.ts
@@ -6,6 +6,7 @@ import {
   agentExecution,
   llmExecution,
   cliAdapterKind,
+  resolveCliModel,
   type CliInvocation,
   type CliAdapterKind,
 } from './cli-adapter.js';
@@ -68,9 +69,10 @@ export async function runAgentCli(
     throw new Error('Lease-bound agent execution requires macOS or Linux process-group cancellation; Windows is unsupported.');
   }
   const kind = cliAdapterKind(cli);
+  const effectiveModel = resolveCliModel(cli, model);
 
   if (mode === 'agent' && transport === 'relay') {
-    return runViaAgentRelay(kind, instruction, wakeContext, model, relayContext, cwd, signal);
+    return runViaAgentRelay(kind, instruction, wakeContext, effectiveModel, relayContext, cwd, signal);
   }
 
   if (kind === 'relayflows-wrapper-v1') {
@@ -78,17 +80,17 @@ export async function runAgentCli(
       cli,
       instruction,
       wakeContext,
-      model,
+      effectiveModel,
       wrapperEnvironment(process.env),
       wrapperLimits,
       signal,
-    )), model);
+    )), effectiveModel);
   }
 
   const env: NodeJS.ProcessEnv = { ...process.env };
   delete env[WAKE_CONTEXT_ENV];
   delete env[MODEL_ENV];
-  const invocation = mode === 'llm' ? llmExecution(kind, instruction, model) : agentExecution(kind, instruction, model);
+  const invocation = mode === 'llm' ? llmExecution(kind, instruction, effectiveModel) : agentExecution(kind, instruction, effectiveModel);
 
   if (wakeContext !== undefined) {
     try {
@@ -106,7 +108,7 @@ export async function runAgentCli(
   // Structured provider output carries the authoritative token counts.
   const args = [...invocation.args];
   args.splice(args.length - 1, 0, ...(kind === 'claude' ? ['--output-format', 'json'] : ['--json']));
-  return requirePricedUsage(decodeProviderResult(await spawnInvocation(cli, { ...invocation, args }, env, signal, sidechannel, cwd), kind), model);
+  return requirePricedUsage(decodeProviderResult(await spawnInvocation(cli, { ...invocation, args }, env, signal, sidechannel, cwd), kind), effectiveModel);
 }
 
 /** Wait under the same worker lease for an authoritative task receipt. */
diff --git a/packages/sdk/src/worker.ts b/packages/sdk/src/worker.ts
index 632e0728d..0dae443e4 100644
--- a/packages/sdk/src/worker.ts
+++ b/packages/sdk/src/worker.ts
@@ -5,6 +5,7 @@ import type { JournalClient } from './journal-client.js';
 import type { Pins, StepDispatchEvent } from './protocol.js';
 import type { KernelAgentStep } from './spec.js';
 import { runAgentCli } from './worker-cli.js';
+import { resolveCliModel } from './cli-adapter.js';
 import { withWorkerLease } from './worker-lease.js';
 import { workerInstruction } from './worker-input.js';
 import { helperCall } from './yaml-helpers.js';
@@ -105,9 +106,10 @@ export class AgentWorker extends EventEmitter {
       return;
     }
     let humanIntervention = false;
+    const effectiveModel = typeof spec.cli === 'string' ? resolveCliModel(spec.cli, spec.model) : spec.model;
     const completed: WorkerCliResult = await withWorkerLease(this.client, dispatch, signal =>
       typeof spec.cli === 'string' && typeof spec.instruction === 'string'
-        ? runAgentCli(spec.cli, workerInstruction(spec.instruction, dispatch), dispatch.wake_context, spec.model, undefined, signal, 'agent', this.options.dataDir === undefined ? undefined : {
+        ? runAgentCli(spec.cli, workerInstruction(spec.instruction, dispatch), dispatch.wake_context, effectiveModel, undefined, signal, 'agent', this.options.dataDir === undefined ? undefined : {
           dataDir: this.options.dataDir, runId: dispatch.run_id, stepId: dispatch.step_id,
           onReady: this.options.onPtyReady, onDrive: () => { humanIntervention = true; },
         }, typeof spec.cwd === 'string' ? spec.cwd : undefined,
@@ -115,7 +117,7 @@ export class AgentWorker extends EventEmitter {
           { runId: dispatch.run_id, stepId: dispatch.step_id, idempotencyKey: dispatch.idempotency_key,
             dataDir: this.options.dataDir, resultSchema: spec.verification?.json_schema })
         : Promise.resolve({ exit_code: null, stdout_tail: '', stderr_tail: 'agent step has no declared CLI' }));
-    const { result, usage } = workerSpend(completed, spec.model);
+    const { result, usage } = workerSpend(completed, effectiveModel);
     const completionReason = result.exit_code === 0 ? 'success' : 'worker_error';
 
     // Output shape: if the CLI's stdout parses as JSON, promote THAT
diff --git a/packages/sdk/tests/adapters/claude.test.ts b/packages/sdk/tests/adapters/claude.test.ts
index f56db9d51..c2b2afb6c 100644
--- a/packages/sdk/tests/adapters/claude.test.ts
+++ b/packages/sdk/tests/adapters/claude.test.ts
@@ -4,6 +4,7 @@ import { claudeAdapter } from '../../src/adapters/claude.js';
 describe('claudeAdapter — HeadlessAdapter contract', () => {
   it('identifies itself as kind "claude"', () => {
     expect(claudeAdapter.kind).toBe('claude');
+    expect(claudeAdapter.defaultModel).toBe('claude-sonnet-4-6');
   });
 
   it('buildIdentification uses the auth-status help shape', () => {
diff --git a/packages/sdk/tests/budget-preflight.test.ts b/packages/sdk/tests/budget-preflight.test.ts
index f6590a959..0a43b6e6c 100644
--- a/packages/sdk/tests/budget-preflight.test.ts
+++ b/packages/sdk/tests/budget-preflight.test.ts
@@ -41,11 +41,22 @@ describe('budget preflight', () => {
     expect(preflight(kernelToAuthoring(toKernelSpec(compileSpec(spec('$20/run', 'unknown')))), options()).diagnostics)
       .toEqual(expect.arrayContaining([expect.objectContaining({kind: 'budget_missing_price'})]));
   });
-  it('requires a model when declaring a dollar budget', () => {
+  it('prices and probes the Claude default when a dollar-budgeted step omits model', () => {
     const input = spec('$20/run');
     const { model, ...step } = input.steps[0]!;
-    expect(preflight({...input, steps:[step]}, options()).diagnostics)
-      .toEqual(expect.arrayContaining([expect.objectContaining({kind: 'budget_missing_price'})]));
+    const o = options();
+    const result = preflight({...input, steps:[step]}, o);
+    expect(result.ok).toBe(true);
+    expect(result.resolutions).toContainEqual(expect.objectContaining({
+      stepId: 'ask', cli: 'claude', model: 'claude-sonnet-4-6',
+    }));
+    expect(o.probes.cli).toHaveBeenCalledWith('claude', 'step', 'claude-sonnet-4-6');
+  });
+  it('still requires a model for an unknown/custom CLI under a dollar budget', () => {
+    const input = spec('$20/run');
+    const { model, ...step } = input.steps[0]!;
+    expect(preflight({...input, steps:[{...step, cli:'team-wrapper'}]}, options()).diagnostics)
+      .toEqual(expect.arrayContaining([expect.objectContaining({kind: 'budget_missing_price', stepId: 'ask'})]));
   });
   it.each(['$1/week', '-$1/run', '$1.0000001/run', {tokens: -1}, {wallclock: 'soon'}, {dollars: Infinity}, {typo: 2}])('refuses malformed budget %j', budget => {
     expect(preflight(spec(budget), options()).ok).toBe(false);
diff --git a/packages/sdk/tests/cli-adapter.test.ts b/packages/sdk/tests/cli-adapter.test.ts
index 6a3811ace..672e4fb34 100644
--- a/packages/sdk/tests/cli-adapter.test.ts
+++ b/packages/sdk/tests/cli-adapter.test.ts
@@ -5,10 +5,17 @@ import {
   authenticationProbe,
   cliAdapterKind,
   modelReadinessProbe,
+  resolveCliModel,
   WRAPPER_IDENTIFY_ARG,
 } from '../src/cli-adapter.js';
 
 describe('typed CLI adapters', () => {
+  it('resolves only Claude to its stable default and preserves explicit models', () => {
+    expect(resolveCliModel('/usr/local/bin/claude')).toBe('claude-sonnet-4-6');
+    expect(resolveCliModel('/usr/local/bin/claude', 'explicit-model')).toBe('explicit-model');
+    expect(resolveCliModel('/opt/bin/codex')).toBeUndefined();
+    expect(resolveCliModel('/project/bin/team-reviewer')).toBeUndefined();
+  });
   it('maps raw Claude to real auth, noninteractive, and model flag shapes', () => {
     const kind = cliAdapterKind('/usr/local/bin/claude');
 
diff --git a/packages/sdk/tests/flow-executor-chain.test.ts b/packages/sdk/tests/flow-executor-chain.test.ts
index 81085c954..3d7bbcf4c 100644
--- a/packages/sdk/tests/flow-executor-chain.test.ts
+++ b/packages/sdk/tests/flow-executor-chain.test.ts
@@ -1,5 +1,5 @@
 import { spawnSync } from 'node:child_process';
-import { existsSync, readFileSync, readdirSync, writeFileSync } from 'node:fs';
+import { chmodSync, existsSync, readFileSync, readdirSync, writeFileSync } from 'node:fs';
 import { once } from 'node:events';
 import { join } from 'node:path';
 import { afterEach, describe, expect, it, vi } from 'vitest';
@@ -66,6 +66,44 @@ describe('flow executor LLM and output-binding chain', () => {
     expect(failures).toEqual([]);
   });
 
+  it('runs a dollar-budgeted authored Claude agent with the same default used by preflight', async () => {
+    const { fixture, client, agent, failures } = await setup();
+    const calls = join(fixture.root, 'claude-calls.jsonl');
+    const claude = join(fixture.root, 'claude');
+    writeFileSync(join(fixture.root, 'flows.json'), JSON.stringify({ models: ['claude-sonnet-4-6'] }));
+    writeFileSync(claude, `#!/usr/bin/env node
+import { appendFileSync } from 'node:fs';
+appendFileSync(${JSON.stringify(calls)}, JSON.stringify(process.argv.slice(2)) + '\\n');
+if (process.argv[2] === 'auth') process.exit(0);
+if (process.argv.includes('Reply with exactly RELAYFLOWS_MODEL_READY and nothing else.')) {
+  process.stdout.write('RELAYFLOWS_MODEL_READY\\n'); process.exit(0);
+}
+process.stdout.write(JSON.stringify({ type: 'result', result: 'default-model-agent-ok',
+  usage: { input_tokens: 2, output_tokens: 1 } }) + '\\n');
+`);
+    chmodSync(claude, 0o755);
+    const handle = flow('default-model-agent', { budget: '$8/run' }, async f => {
+      const result = await f.agent('implementer', { cli: claude, task: 'Implement.' });
+      expect(result.summary).toBe('default-model-agent-ok');
+      f.done('success');
+    });
+
+    const result = await executeAuthoredFlow(handle, client, undefined, {
+      flowPath: fixture.flowPath, localAgentStream: agent.stream,
+    });
+
+    expect(result.completionReason).toBe('success');
+    const invocations = readFileSync(calls, 'utf8').trim().split('\n').map(line => JSON.parse(line) as string[]);
+    const modelScoped = invocations.filter(args => args.includes('--model'));
+    expect(modelScoped).toHaveLength(2);
+    expect(modelScoped.every(args => args[args.indexOf('--model') + 1] === 'claude-sonnet-4-6')).toBe(true);
+    expect(modelScoped.at(-1)).toEqual([
+      '-p', '--dangerously-skip-permissions', '--model', 'claude-sonnet-4-6',
+      '--output-format', 'json', expect.stringContaining('Implement.'),
+    ]);
+    expect(failures).toEqual([]);
+  });
+
   it.each(['not JSON', '{"message":7}'])('fails invalid LLM output before the next step: %s', async output => {
     const { fixture, client, agent, failures } = await setup(output);
     const marker = join(fixture.root, 'must-not-exist');
diff --git a/packages/sdk/tests/pty-sidechannel.test.ts b/packages/sdk/tests/pty-sidechannel.test.ts
index 3091577b0..4d4dff816 100644
--- a/packages/sdk/tests/pty-sidechannel.test.ts
+++ b/packages/sdk/tests/pty-sidechannel.test.ts
@@ -47,7 +47,7 @@ setTimeout(() => process.exit(0), 450);
   client.emit('step.dispatch', {
     run_id: 'r', step_id: 's', step_type: 'agent', attempt: 1,
     idempotency_key: 'k', lease_id: 'lease', lease_deadline_ms: Date.now() + 60_000,
-    pins: { workspace: [], streams: [] }, spec: { cli, instruction: 'test' },
+    pins: { workspace: [], streams: [] }, spec: { cli, model: 'pty-test-model', instruction: 'test' },
   });
   try {
     const args = await done;
@@ -84,7 +84,7 @@ process.stdin.on('end', () => { clearTimeout(watchdog); process.stdout.write('eo
   let peer: Socket | undefined;
   let driven = false;
   try {
-    const result = await runAgentCli(cli, 'test', undefined, undefined, undefined, undefined, 'agent', {
+    const result = await runAgentCli(cli, 'test', undefined, 'pty-test-model', undefined, undefined, 'agent', {
       dataDir, runId: 'r', stepId: 's', onDrive: () => { driven = true; },
       onReady(path) {
         if (mode === 'none') return;
@@ -112,7 +112,7 @@ process.stdin.on('end', () => {
   let attempted = false;
   let rejectedBeforeExit = false;
   try {
-    const result = await runAgentCli(cli, 'test', undefined, undefined, undefined, undefined, 'agent', {
+    const result = await runAgentCli(cli, 'test', undefined, 'pty-test-model', undefined, undefined, 'agent', {
       dataDir, runId: 'r', stepId: 's', onDrive: () => { driven = true; },
       onReady(path) {
         peer = connect(path, () => peer!.write('HELLO view\n'));
@@ -154,7 +154,7 @@ setTimeout(() => {
   const controller = new AbortController();
   const timeout = setTimeout(() => controller.abort(), 4000);
   try {
-    const result = await runAgentCli(cli, 'test', undefined, undefined, undefined, controller.signal, 'agent', {
+    const result = await runAgentCli(cli, 'test', undefined, 'pty-test-model', undefined, controller.signal, 'agent', {
       dataDir, runId: 'r', stepId: 's', onDrive() {},
       onReady(path) {
         peer = connect(path, () => { peer!.write('HELLO drive\n'); peer!.write(payload); });
diff --git a/packages/sdk/tests/worker-cli.test.ts b/packages/sdk/tests/worker-cli.test.ts
index 481aecb90..364166f5b 100644
--- a/packages/sdk/tests/worker-cli.test.ts
+++ b/packages/sdk/tests/worker-cli.test.ts
@@ -2,6 +2,7 @@ import {
   chmodSync,
   existsSync,
   mkdtempSync,
+  readFileSync,
   realpathSync,
   rmSync,
   symlinkSync,
@@ -56,6 +57,28 @@ async function withEnvironment<T>(
   }
 }
 
+describe('registered CLI model defaults', () => {
+  it('passes the same priced Claude default to the real provider invocation', async () => {
+    const directory = makeDirectory();
+    const calls = join(directory, 'calls.json');
+    const claude = makeWrapper(directory, 'claude', `
+const fs = require('node:fs');
+fs.writeFileSync(${JSON.stringify(calls)}, JSON.stringify(process.argv.slice(2)));
+process.stdout.write(JSON.stringify({ type: 'result', result: 'default-model-ok',
+  usage: { input_tokens: 2, output_tokens: 1 } }) + '\\n');
+`);
+
+    const result = await runAgentCli(claude, 'do the task', undefined);
+
+    expect(result).toMatchObject({ exit_code: 0, stdout_tail: 'default-model-ok',
+      tokens_input: 2, tokens_output: 1 });
+    expect(JSON.parse(readFileSync(calls, 'utf8'))).toEqual([
+      '-p', '--dangerously-skip-permissions', '--model', 'claude-sonnet-4-6',
+      '--output-format', 'json', 'do the task',
+    ]);
+  });
+});
+
 describe('custom wrapper execution identity', () => {
   it('passes an explicit safe environment at identification and execution', async () => {
     const directory = makeDirectory();

From 22c5a6de7a2dd583e02a5a0c4e2e5010bda6f0ba Mon Sep 17 00:00:00 2001
From: Miya <khaliqgant+miya@gmail.com>
Date: Tue, 15 Sep 2026 18:56:23 +0200
Subject: [PATCH 2/3] test: allow the Claude default in shared fixtures

Session-Id: 01a09c40-ce3b-7f11-a7df-b6b7ccab6fd9
---
 testdata/flows.json | 1 +
 1 file changed, 1 insertion(+)

diff --git a/testdata/flows.json b/testdata/flows.json
index 3396475ca..4692d4bc5 100644
--- a/testdata/flows.json
+++ b/testdata/flows.json
@@ -3,6 +3,7 @@
   "executors": ["agent-worker"],
   "models": [
     "claude-haiku-4-5-20251001",
+    "claude-sonnet-4-6",
     "claude-sonnet-5",
     "deterministic-test-stub",
     "test-model-v1"

From c77be1987d80d46b1d1dba3e3c6bb7ec9cd51f72 Mon Sep 17 00:00:00 2001
From: Miya <khaliqgant+miya@gmail.com>
Date: Tue, 15 Sep 2026 19:31:12 +0200
Subject: [PATCH 3/3] fix(sdk): default Claude steps to Opus 5

Session-Id: 01a09c40-ce3b-7f11-a7df-b6b7ccab6fd9
---
 docs/SURFACE.md                               | 15 ++---
 packages/schema/flows.schema.json             |  2 +-
 packages/schema/tests/parity.test.ts          |  4 +-
 packages/sdk/src/adapters/base.ts             |  6 +-
 packages/sdk/src/adapters/claude.ts           |  2 +-
 packages/sdk/src/budget-preflight.ts          | 13 +++--
 packages/sdk/src/cli-adapter.ts               | 27 ++++++++-
 packages/sdk/src/cli/check.ts                 |  5 +-
 packages/sdk/src/model-pricing.ts             |  1 +
 packages/sdk/src/preflight.ts                 | 30 ++++++----
 packages/sdk/src/spec.ts                      |  9 +--
 packages/sdk/tests/adapters/claude.test.ts    |  2 +-
 packages/sdk/tests/budget-preflight.test.ts   | 57 +++++++++++++++++--
 packages/sdk/tests/cli-adapter.test.ts        | 10 +++-
 .../sdk/tests/flow-executor-chain.test.ts     |  6 +-
 packages/sdk/tests/model-pricing.test.ts      |  6 ++
 packages/sdk/tests/preflight.test.ts          | 21 ++++---
 packages/sdk/tests/verb-field-lint.test.ts    |  4 +-
 packages/sdk/tests/worker-cli.test.ts         |  2 +-
 testdata/flows.json                           |  1 -
 20 files changed, 162 insertions(+), 61 deletions(-)

diff --git a/docs/SURFACE.md b/docs/SURFACE.md
index 68aa8539e..96bcc881d 100644
--- a/docs/SURFACE.md
+++ b/docs/SURFACE.md
@@ -144,13 +144,14 @@ No process runs between events: the handler wakes, executes to its next await, p
    the existing per-step `cli` and `model` fields. The validated selector and
    map remain authoring metadata through `flows check`, so unused and
    step-shadowed declarations are linted too; both are removed at the kernel
-   boundary. Explicit step values win independently:
-   step `cli`/`model` → named declaration → the existing flow/project CLI
-   default. Model has no flow/project default. An inline step that selects no
-   named declaration keeps the existing optional-model behavior. The worker
-   explicitly removes ambient `RELAYFLOW_MODEL`; raw provider adapters use a
-   model flag, while at worker execution a custom wrapper receives the model
-   only inside its identified same-process session when the step declares one.
+   boundary. CLI and model resolve independently. CLI priority is step → named
+   declaration → flow → project config. Model priority is step → named
+   declaration → registered adapter default. Claude's adapter default is
+   `claude-opus-5`; Codex and custom wrappers have no default. A frozen dollar
+   budget refuses before execution when the selected model has no frozen price.
+   The worker explicitly removes ambient `RELAYFLOW_MODEL`; raw provider
+   adapters use a model flag, while a custom wrapper receives an explicitly
+   declared model only inside its identified same-process session.
 
    **Anonymous resolution law:** `f.agent\`task\`` with no name is the *default agent*, resolved (never guessed) in order: step options → flow header → project config (`flows.json`) → platform default. *The platform-default rung is declared but not yet implemented: no platform default is provisioned as of gate 1, so a flow that reaches this rung refuses with `cli_unresolved` rather than guessing. `flows check` never invents an implicit default.* `flows check` prints each resolved step CLI and its declaration source, validates it before submission, and refuses a missing or unauthenticated resolution before the checked flow is submitted, never at minute 27. Gate 1 does not make this guarantee for callers that bypass `flows check`: the journal client's direct `run.start` path does not invoke surface preflight.
 
diff --git a/packages/schema/flows.schema.json b/packages/schema/flows.schema.json
index 5da42e0b9..3cbc4c37a 100644
--- a/packages/schema/flows.schema.json
+++ b/packages/schema/flows.schema.json
@@ -1296,7 +1296,7 @@
         },
         "model": {
           "title": "model",
-          "description": "Model the declared CLI must use. Raw Claude/Codex adapters receive their\nreal model flag; an identified Relayflows wrapper receives it in its\nsame-process execution request. Declared here so the choice is journaled with the step\ninstead of being ambient host state.",
+          "description": "Model the declared CLI must use. A step declaration wins over its selected\nnamed agent and any registered adapter default. Raw Claude/Codex adapters\nreceive the effective model as a real flag; an identified Relayflows\nwrapper receives an explicitly declared model in its same-process request.\nThe effective choice is journaled instead of being ambient host state.",
           "type": "string",
           "minLength": 1,
           "pattern": "^\\S(?:[\\s\\S]*\\S)?$",
diff --git a/packages/schema/tests/parity.test.ts b/packages/schema/tests/parity.test.ts
index d50d9f61f..bb6a32766 100644
--- a/packages/schema/tests/parity.test.ts
+++ b/packages/schema/tests/parity.test.ts
@@ -19,7 +19,9 @@ mkdirSync(join(root, 'bin'));
 // every check must agree, including environment readiness (no ignored refusals).
 const wrapper = '#!/bin/sh\nif [ "$1" = "--relayflows-adapter-v1" ]; then echo relayflows-agent-cli-v1; fi\nexit 0\n';
 for (const file of ['preflight/authenticated-cli', 'preflight/analyze-story-claude-cli', 'bin/claude']) writeFileSync(join(root, file), wrapper, { mode: 0o755 });
-writeFileSync(join(root, 'flows.json'), readFileSync(new URL('../../../testdata/flows.json', import.meta.url)));
+const parityConfig = JSON.parse(readFileSync(new URL('../../../testdata/flows.json', import.meta.url), 'utf8'));
+parityConfig.models.push('claude-opus-5');
+writeFileSync(join(root, 'flows.json'), JSON.stringify(parityConfig));
 const oldPath = process.env.PATH;
 process.env.PATH = `${join(root, 'bin')}:${oldPath ?? ''}`;
 afterAll(() => { process.env.PATH = oldPath; rmSync(root, { recursive: true, force: true }); });
diff --git a/packages/sdk/src/adapters/base.ts b/packages/sdk/src/adapters/base.ts
index da0d1da38..6df66ea06 100644
--- a/packages/sdk/src/adapters/base.ts
+++ b/packages/sdk/src/adapters/base.ts
@@ -32,7 +32,11 @@ export interface HeadlessAdapter {
   /** Identity of this adapter — matches CliAdapterKind for registry keys. */
   readonly kind: string;
 
-  /** Stable model used when an author omits one. */
+  /**
+   * Stable model used only when neither the step nor its selected named agent
+   * declares one. Explicit authoring always wins. A default used with frozen
+   * dollar budgets must also have an entry in MODEL_PRICING.
+   */
   readonly defaultModel?: string;
 
   /** Shape-check invocation before classifying an auth failure. */
diff --git a/packages/sdk/src/adapters/claude.ts b/packages/sdk/src/adapters/claude.ts
index 187d4c9c6..e27d906e1 100644
--- a/packages/sdk/src/adapters/claude.ts
+++ b/packages/sdk/src/adapters/claude.ts
@@ -10,7 +10,7 @@ const MODEL_PROBE_PROMPT = 'Reply with exactly RELAYFLOWS_MODEL_READY and nothin
  *  pre-#141 inline shape in `cli-adapter.ts` — only the packaging changed. */
 export const claudeAdapter: HeadlessAdapter = {
   kind: 'claude',
-  defaultModel: 'claude-sonnet-4-6',
+  defaultModel: 'claude-opus-5',
 
   buildIdentification(): CliAdapterIdentification {
     return { invocation: { args: ['auth', 'status', '--help'], timeoutMs: 10_000 } };
diff --git a/packages/sdk/src/budget-preflight.ts b/packages/sdk/src/budget-preflight.ts
index 319c77fc9..1c2172a1e 100644
--- a/packages/sdk/src/budget-preflight.ts
+++ b/packages/sdk/src/budget-preflight.ts
@@ -1,11 +1,12 @@
 import type { CompiledFlowSpec } from './compile.js';
 import type { PreflightRefusal } from './preflight.js';
 import { MODEL_PRICING } from './model-pricing.js';
+import type { ResolvedCliModel } from './cli-adapter.js';
 
-/** Legacy explicit envelopes keep their worker-supplied pricing contract. */
+/** Frozen dollar budgets require an exact model with a frozen table price. */
 export function budgetDiagnostics(
   flow: CompiledFlowSpec,
-  resolvedModels: ReadonlyMap<string, string | undefined> = new Map(),
+  resolvedModels: ReadonlyMap<string, ResolvedCliModel> = new Map(),
 ): PreflightRefusal[] {
   if (flow.budget?.pricing !== 'frozen') return [];
   const diagnostics: PreflightRefusal[] = [];
@@ -16,15 +17,15 @@ export function budgetDiagnostics(
   ];
   for (const step of flow.steps) {
     if (step.type === 'deterministic' || flow.budget.maxDollars === undefined) continue;
-    const model = resolvedModels.has(step.id) ? resolvedModels.get(step.id)
-      : step.model ?? (step.type === 'agent' && step.agent !== undefined
+    const resolved = resolvedModels.get(step.id);
+    const model = resolved?.model
+      ?? step.model ?? (step.type === 'agent' && step.agent !== undefined
         ? flow.agents?.[step.agent]?.model : undefined);
     if (model === undefined) diagnostics.push({
       severity: 'refusal', kind: 'budget_missing_price', stepId: step.id,
       message: `Step "${step.id}" needs a declared, priced model for its dollar budget.`,
     });
-    else if (step.model === undefined
-      && (step.type !== 'agent' || step.agent === undefined || flow.agents?.[step.agent]?.model === undefined)
+    else if (resolved?.source === 'adapter'
       && !Object.hasOwn(MODEL_PRICING, model)) diagnostics.push({
       severity: 'refusal', kind: 'budget_missing_price', stepId: step.id, model,
       message: `Model "${model}" has no frozen price for budget accounting.`,
diff --git a/packages/sdk/src/cli-adapter.ts b/packages/sdk/src/cli-adapter.ts
index a7ac82e2b..8d3ace41d 100644
--- a/packages/sdk/src/cli-adapter.ts
+++ b/packages/sdk/src/cli-adapter.ts
@@ -28,10 +28,31 @@ export function cliAdapterKind(executable: string): CliAdapterKind {
   return resolveAdapterKind(executable);
 }
 
-/** Resolve only defaults owned by registered raw-CLI adapters. */
+export type CliModelSource = 'step' | 'named' | 'adapter';
+
+export interface ResolvedCliModel {
+  readonly model?: string;
+  readonly source?: CliModelSource;
+}
+
+/**
+ * Resolve the model once, in authoring priority order: step, selected named
+ * agent, then the registered CLI adapter's default. Unregistered executables
+ * resolve through the wrapper adapter, whose absent default remains undefined.
+ */
+export function resolveCliModelSelection(
+  executable: string,
+  declarations: Readonly<{ step?: string; named?: string }> = {},
+): ResolvedCliModel {
+  if (declarations.step !== undefined) return { model: declarations.step, source: 'step' };
+  if (declarations.named !== undefined) return { model: declarations.named, source: 'named' };
+  const model = registeredAdapters()[resolveAdapterKind(executable)].defaultModel;
+  return model === undefined ? {} : { model, source: 'adapter' };
+}
+
+/** Resolve a runtime model, where any materialized value is step-owned. */
 export function resolveCliModel(executable: string, model?: string): string | undefined {
-  if (model !== undefined) return model;
-  return registeredAdapters()[resolveAdapterKind(executable)].defaultModel;
+  return resolveCliModelSelection(executable, { step: model }).model;
 }
 
 /** Prove the adapter command shape before classifying an auth failure. */
diff --git a/packages/sdk/src/cli/check.ts b/packages/sdk/src/cli/check.ts
index f9f56d81d..d6a2bf2c5 100644
--- a/packages/sdk/src/cli/check.ts
+++ b/packages/sdk/src/cli/check.ts
@@ -358,10 +358,9 @@ function bindResolvedCliPaths(
       const resolution = byStep.get(step.id);
       if (resolution === undefined) return step;
       const directory = resolution.source === 'project' ? configDirectory : flowDirectory;
-      const declaredModel = step.model ?? (step.type === 'agent' && step.agent !== undefined
-        ? flow.agents?.[step.agent]?.model : undefined);
       return { ...step, cli: canonicalCli(resolution.cli, directory),
-        ...(declaredModel === undefined && resolution.model !== undefined ? { model: resolution.model } : {}) };
+        ...(resolution.modelSource === 'adapter' && resolution.model !== undefined
+          ? { model: resolution.model } : {}) };
     }),
   };
 }
diff --git a/packages/sdk/src/model-pricing.ts b/packages/sdk/src/model-pricing.ts
index 04672fe93..d41ecda79 100644
--- a/packages/sdk/src/model-pricing.ts
+++ b/packages/sdk/src/model-pricing.ts
@@ -2,6 +2,7 @@
 export const MODEL_PRICING: Readonly<Record<string, Readonly<{ input: number; output: number }>>> = Object.freeze({
   'claude-sonnet-4-6': Object.freeze({ input: 3, output: 15 }),
   'claude-opus-4-7': Object.freeze({ input: 15, output: 75 }),
+  'claude-opus-5': Object.freeze({ input: 5, output: 25 }),
   'codex-medium': Object.freeze({ input: 2, output: 8 }),
   'codex-large': Object.freeze({ input: 5, output: 20 }),
 });
diff --git a/packages/sdk/src/preflight.ts b/packages/sdk/src/preflight.ts
index f42a37acd..31107bd81 100644
--- a/packages/sdk/src/preflight.ts
+++ b/packages/sdk/src/preflight.ts
@@ -8,7 +8,7 @@ import type { TriggerSource } from '@relayflows/surface';
 import { acceptsAnyOutput, inspectStepGate, type StepGateInspection } from './gate-contract.js';
 import { compileSpec, CompileError } from './compile.js';
 import { helperCall } from './yaml-helpers.js';
-import { resolveCliModel } from './cli-adapter.js';
+import { resolveCliModelSelection, type CliModelSource } from './cli-adapter.js';
 import { isNamedGate, NAMED_GATE_FAILURE_KINDS, type NamedGateFailureKind } from './named-gates.js';
 import { compileScopes, type ScopeInput, type MountRegistry } from './scope-compiler.js';
 import { readMountRegistry } from './mount-registry.js';
@@ -23,8 +23,10 @@ export interface CliResolution {
   stepId: string;
   cli: string;
   source: CliResolutionSource;
-  /** Model the step or selected named agent declared, probed with the CLI. */
+  /** Effective model probed with the CLI. */
   model?: string;
+  /** Exact source selected by step > named agent > adapter default priority. */
+  modelSource?: CliModelSource;
 }
 
 export interface CliProbeResult {
@@ -239,11 +241,17 @@ function preflightSync(flow: unknown, options: PreflightOptions): PreflightResul
       resolutionByStep.set(step.id, resolution);
     }
   }
-  diagnostics.push(...unknownModelDiagnostics(compiled, options, resolutionByStep));
   diagnostics.push(...cliResolutionDiagnostics);
+  if (cliResolutionDiagnostics.length > 0) {
+    return { ok: false, gates: compiled.steps.map(inspectStepGate), resolutions, diagnostics };
+  }
+  diagnostics.push(...unknownModelDiagnostics(compiled, options, resolutionByStep));
   diagnostics.push(...budgetDiagnostics(
     compiled,
-    new Map(resolutions.map(resolution => [resolution.stepId, resolution.model])),
+    new Map(resolutions.map(resolution => [resolution.stepId, {
+      ...(resolution.model === undefined ? {} : { model: resolution.model }),
+      ...(resolution.modelSource === undefined ? {} : { source: resolution.modelSource }),
+    }])),
   ));
   if (diagnostics.length > 0) {
     return { ok: false, gates: compiled.steps.map(inspectStepGate), resolutions, diagnostics };
@@ -348,11 +356,11 @@ function unknownModelDiagnostics(
 
   for (const step of flow.steps) {
     if (step.type === 'deterministic') continue;
-    const named = step.type === 'agent' && step.agent !== undefined
-      ? flow.agents?.[step.agent] : undefined;
-    if (step.model === undefined && named !== undefined) continue;
     const resolution = resolutionByStep.get(step.id);
-    const model = step.model ?? resolution?.model;
+    // Selected named declarations were checked once above, including unused
+    // declarations. Other sources are step declarations or adapter defaults.
+    if (resolution?.modelSource === 'named') continue;
+    const model = resolution?.model ?? step.model;
     if (model === undefined || isKnownModel(model, options.models)) continue;
     if (!enforceRegistry) continue;
     diagnostics.push({
@@ -414,11 +422,11 @@ function resolveCli(
   const named = step.type === 'agent' && step.agent !== undefined
     ? flow.agents?.[step.agent]
     : undefined;
-  const declaredModel = step.model ?? named?.model;
   const resolved = (cli: string, source: CliResolutionSource): CliResolution => {
-    const effectiveModel = resolveCliModel(cli, declaredModel);
+    const effectiveModel = resolveCliModelSelection(cli, { step: step.model, named: named?.model });
     return { stepId: step.id, cli, source,
-      ...(effectiveModel === undefined ? {} : { model: effectiveModel }) };
+      ...(effectiveModel.model === undefined ? {} : { model: effectiveModel.model }),
+      ...(effectiveModel.source === undefined ? {} : { modelSource: effectiveModel.source }) };
   };
   if (step.cli !== undefined) return resolved(step.cli, 'step');
   if (named !== undefined) return resolved(named.cli, 'named');
diff --git a/packages/sdk/src/spec.ts b/packages/sdk/src/spec.ts
index 838e21bee..1cc48533a 100644
--- a/packages/sdk/src/spec.ts
+++ b/packages/sdk/src/spec.ts
@@ -238,10 +238,11 @@ export interface AgentStepSpec extends BaseStepSpec {
   /** Inert preflight declaration; overrides the flow/project CLI default. */
   cli?: string;
   /**
-   * Model the declared CLI must use. Raw Claude/Codex adapters receive their
-   * real model flag; an identified Relayflows wrapper receives it in its
-   * same-process execution request. Declared here so the choice is journaled with the step
-   * instead of being ambient host state.
+   * Model the declared CLI must use. A step declaration wins over its selected
+   * named agent and any registered adapter default. Raw Claude/Codex adapters
+   * receive the effective model as a real flag; an identified Relayflows
+   * wrapper receives an explicitly declared model in its same-process request.
+   * The effective choice is journaled instead of being ambient host state.
    */
   model?: string;
   surfaces?: AgentSurfaces;
diff --git a/packages/sdk/tests/adapters/claude.test.ts b/packages/sdk/tests/adapters/claude.test.ts
index c2b2afb6c..c1e252ff2 100644
--- a/packages/sdk/tests/adapters/claude.test.ts
+++ b/packages/sdk/tests/adapters/claude.test.ts
@@ -4,7 +4,7 @@ import { claudeAdapter } from '../../src/adapters/claude.js';
 describe('claudeAdapter — HeadlessAdapter contract', () => {
   it('identifies itself as kind "claude"', () => {
     expect(claudeAdapter.kind).toBe('claude');
-    expect(claudeAdapter.defaultModel).toBe('claude-sonnet-4-6');
+    expect(claudeAdapter.defaultModel).toBe('claude-opus-5');
   });
 
   it('buildIdentification uses the auth-status help shape', () => {
diff --git a/packages/sdk/tests/budget-preflight.test.ts b/packages/sdk/tests/budget-preflight.test.ts
index 0a43b6e6c..b2649022f 100644
--- a/packages/sdk/tests/budget-preflight.test.ts
+++ b/packages/sdk/tests/budget-preflight.test.ts
@@ -3,8 +3,9 @@ import { preflight } from '../src/preflight.js';
 import { compileSpec, CompileError, toKernelSpec, kernelToAuthoring } from '../src/compile.js';
 import { flow } from '@relayflows/surface';
 import { getFlowDefinition } from '@relayflows/surface/runtime';
+import { budgetDiagnostics } from '../src/budget-preflight.js';
 
-const options = () => ({models: ['claude-sonnet-4-6', 'unknown'], probes: {
+const options = () => ({models: ['claude-opus-5', 'claude-opus-4-7', 'claude-sonnet-4-6', 'unknown'], probes: {
   cli: vi.fn(() => ({ exists: true, authenticated: true, modelAvailable: true })),
   executor: () => true, command: () => true,
 }});
@@ -48,16 +49,62 @@ describe('budget preflight', () => {
     const result = preflight({...input, steps:[step]}, o);
     expect(result.ok).toBe(true);
     expect(result.resolutions).toContainEqual(expect.objectContaining({
-      stepId: 'ask', cli: 'claude', model: 'claude-sonnet-4-6',
+      stepId: 'ask', cli: 'claude', model: 'claude-opus-5', modelSource: 'adapter',
     }));
-    expect(o.probes.cli).toHaveBeenCalledWith('claude', 'step', 'claude-sonnet-4-6');
+    expect(o.probes.cli).toHaveBeenCalledWith('claude', 'step', 'claude-opus-5');
   });
-  it('still requires a model for an unknown/custom CLI under a dollar budget', () => {
+  it.each(['codex', 'team-wrapper'])('still requires a model for registered/custom CLI %s with no default under a dollar budget', cli => {
     const input = spec('$20/run');
     const { model, ...step } = input.steps[0]!;
-    expect(preflight({...input, steps:[{...step, cli:'team-wrapper'}]}, options()).diagnostics)
+    expect(preflight({...input, steps:[{...step, cli}]}, options()).diagnostics)
       .toEqual(expect.arrayContaining([expect.objectContaining({kind: 'budget_missing_price', stepId: 'ask'})]));
   });
+  it('refuses an unpriced adapter default under a frozen dollar budget', () => {
+    const input = compileSpec(spec('$20/run'));
+    const { model, ...step } = input.steps[0]!;
+    expect(budgetDiagnostics({...input, steps:[step]}, new Map([
+      ['ask', { model: 'future-default', source: 'adapter' as const }],
+    ]))).toEqual([expect.objectContaining({
+      kind: 'budget_missing_price', stepId: 'ask', model: 'future-default',
+    })]);
+  });
+  it('resolves and probes the adapter default without requiring price for a token-only budget', () => {
+    const input = spec({ tokens: 100 });
+    const { model, ...step } = input.steps[0]!;
+    const o = options();
+    const result = preflight({...input, steps:[step]}, o);
+    expect(result.ok).toBe(true);
+    expect(result.resolutions).toContainEqual(expect.objectContaining({
+      stepId: 'ask', model: 'claude-opus-5', modelSource: 'adapter',
+    }));
+    expect(o.probes.cli).toHaveBeenCalledWith('claude', 'step', 'claude-opus-5');
+  });
+  it('uses a selected named-agent model ahead of the Claude adapter default', () => {
+    const o = options();
+    const result = preflight({
+      version: '0.1.0',
+      budget: '$20/run',
+      agents: { reviewer: { cli: 'claude', model: 'claude-opus-4-7' } },
+      steps: [{ id: 'ask', type: 'agent', agent: 'reviewer', instruction: 'Review.' }],
+    }, o);
+    expect(result.ok).toBe(true);
+    expect(result.resolutions).toEqual([expect.objectContaining({
+      stepId: 'ask', cli: 'claude', model: 'claude-opus-4-7', modelSource: 'named',
+    })]);
+    expect(o.probes.cli).toHaveBeenCalledWith('claude', 'named', 'claude-opus-4-7');
+  });
+  it('enforces the model allowlist on an implicit Claude default before probing', () => {
+    const input = spec('$20/run');
+    const { model, ...step } = input.steps[0]!;
+    const o = options();
+    const result = preflight({...input, steps:[step]}, {
+      ...o, models: ['claude-sonnet-4-6'], modelRegistryPath: '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/project/flows.json',
+    });
+    expect(result.diagnostics).toEqual([expect.objectContaining({
+      kind: 'model_unknown', stepId: 'ask', model: 'claude-opus-5',
+    })]);
+    expect(o.probes.cli).not.toHaveBeenCalled();
+  });
   it.each(['$1/week', '-$1/run', '$1.0000001/run', {tokens: -1}, {wallclock: 'soon'}, {dollars: Infinity}, {typo: 2}])('refuses malformed budget %j', budget => {
     expect(preflight(spec(budget), options()).ok).toBe(false);
   });
diff --git a/packages/sdk/tests/cli-adapter.test.ts b/packages/sdk/tests/cli-adapter.test.ts
index 672e4fb34..0fd07ac73 100644
--- a/packages/sdk/tests/cli-adapter.test.ts
+++ b/packages/sdk/tests/cli-adapter.test.ts
@@ -6,15 +6,23 @@ import {
   cliAdapterKind,
   modelReadinessProbe,
   resolveCliModel,
+  resolveCliModelSelection,
   WRAPPER_IDENTIFY_ARG,
 } from '../src/cli-adapter.js';
 
 describe('typed CLI adapters', () => {
   it('resolves only Claude to its stable default and preserves explicit models', () => {
-    expect(resolveCliModel('/usr/local/bin/claude')).toBe('claude-sonnet-4-6');
+    expect(resolveCliModel('/usr/local/bin/claude')).toBe('claude-opus-5');
     expect(resolveCliModel('/usr/local/bin/claude', 'explicit-model')).toBe('explicit-model');
     expect(resolveCliModel('/opt/bin/codex')).toBeUndefined();
     expect(resolveCliModel('/project/bin/team-reviewer')).toBeUndefined();
+    expect(resolveCliModelSelection('claude', { step: 'step-model', named: 'named-model' }))
+      .toEqual({ model: 'step-model', source: 'step' });
+    expect(resolveCliModelSelection('claude', { named: 'named-model' }))
+      .toEqual({ model: 'named-model', source: 'named' });
+    expect(resolveCliModelSelection('claude')).toEqual({ model: 'claude-opus-5', source: 'adapter' });
+    expect(resolveCliModelSelection('codex')).toEqual({});
+    expect(resolveCliModelSelection('team-reviewer')).toEqual({});
   });
   it('maps raw Claude to real auth, noninteractive, and model flag shapes', () => {
     const kind = cliAdapterKind('/usr/local/bin/claude');
diff --git a/packages/sdk/tests/flow-executor-chain.test.ts b/packages/sdk/tests/flow-executor-chain.test.ts
index 3d7bbcf4c..fd171549b 100644
--- a/packages/sdk/tests/flow-executor-chain.test.ts
+++ b/packages/sdk/tests/flow-executor-chain.test.ts
@@ -70,7 +70,7 @@ describe('flow executor LLM and output-binding chain', () => {
     const { fixture, client, agent, failures } = await setup();
     const calls = join(fixture.root, 'claude-calls.jsonl');
     const claude = join(fixture.root, 'claude');
-    writeFileSync(join(fixture.root, 'flows.json'), JSON.stringify({ models: ['claude-sonnet-4-6'] }));
+    writeFileSync(join(fixture.root, 'flows.json'), JSON.stringify({ models: ['claude-opus-5'] }));
     writeFileSync(claude, `#!/usr/bin/env node
 import { appendFileSync } from 'node:fs';
 appendFileSync(${JSON.stringify(calls)}, JSON.stringify(process.argv.slice(2)) + '\\n');
@@ -96,9 +96,9 @@ process.stdout.write(JSON.stringify({ type: 'result', result: 'default-model-age
     const invocations = readFileSync(calls, 'utf8').trim().split('\n').map(line => JSON.parse(line) as string[]);
     const modelScoped = invocations.filter(args => args.includes('--model'));
     expect(modelScoped).toHaveLength(2);
-    expect(modelScoped.every(args => args[args.indexOf('--model') + 1] === 'claude-sonnet-4-6')).toBe(true);
+    expect(modelScoped.every(args => args[args.indexOf('--model') + 1] === 'claude-opus-5')).toBe(true);
     expect(modelScoped.at(-1)).toEqual([
-      '-p', '--dangerously-skip-permissions', '--model', 'claude-sonnet-4-6',
+      '-p', '--dangerously-skip-permissions', '--model', 'claude-opus-5',
       '--output-format', 'json', expect.stringContaining('Implement.'),
     ]);
     expect(failures).toEqual([]);
diff --git a/packages/sdk/tests/model-pricing.test.ts b/packages/sdk/tests/model-pricing.test.ts
index bc0c0182b..42f9184e3 100644
--- a/packages/sdk/tests/model-pricing.test.ts
+++ b/packages/sdk/tests/model-pricing.test.ts
@@ -8,6 +8,12 @@ describe('pricedUsage', () => {
     expect(usage).toEqual({ tokens_in: 1_000_000, tokens_out: 500_000, dollars: '10.500000' });
   });
 
+  it('uses the frozen Claude Opus 5 standard rate', () => {
+    expect(pricedUsage('claude-opus-5', 1_000_000, 500_000)).toEqual({
+      tokens_in: 1_000_000, tokens_out: 500_000, dollars: '17.500000',
+    });
+  });
+
   it('returns undefined for an unpriced model rather than throwing after decode', () => {
     // Regression for the Cursor Bugbot HIGH finding "Unlisted models fail
     // after usage decode": the runtime previously threw here after the CLI
diff --git a/packages/sdk/tests/preflight.test.ts b/packages/sdk/tests/preflight.test.ts
index 12fc70f7e..cd0f64dbf 100644
--- a/packages/sdk/tests/preflight.test.ts
+++ b/packages/sdk/tests/preflight.test.ts
@@ -37,7 +37,7 @@ describe('preflight: CLI resolution and refusal predicates', () => {
     const calls: Array<[string, string, string | undefined]> = [];
     const authored: FlowSpec = {
       version: '0.1.0',
-      agents: { reviewer: { cli: 'wrapper', model: 'allowed-model' } },
+      agents: { reviewer: { cli: 'claude', model: 'allowed-model' } },
       steps: [{ id: 'review', type: 'agent', agent: 'reviewer', instruction: 'Review.' }],
     };
 
@@ -54,11 +54,12 @@ describe('preflight: CLI resolution and refusal predicates', () => {
     expect(result.ok).toBe(true);
     expect(result.resolutions).toEqual([{
       stepId: 'review',
-      cli: 'wrapper',
+      cli: 'claude',
       source: 'named',
       model: 'allowed-model',
+      modelSource: 'named',
     }]);
-    expect(calls).toEqual([['wrapper', 'named', 'allowed-model']]);
+    expect(calls).toEqual([['claude', 'named', 'allowed-model']]);
   });
 
   it('refuses malformed raw input before any public preflight probe', () => {
@@ -144,6 +145,7 @@ describe('preflight: CLI resolution and refusal predicates', () => {
       const unresolved: FlowSpec['steps'][number] = {
         id: 'unresolved',
         type: 'agent',
+        model: 'must-not-check',
         instruction: 'No CLI is declared.',
       };
       const resolvable: FlowSpec['steps'][number] = {
@@ -154,11 +156,14 @@ describe('preflight: CLI resolution and refusal predicates', () => {
       };
       const result = preflight({
         version: '0.1.0',
+        budget: '$1/run',
         steps: order === 'unresolved first'
           ? [unresolved, resolvable, { id: 'command', type: 'deterministic', command: 'printf ready' }]
           : [{ id: 'command', type: 'deterministic', command: 'printf ready' }, resolvable, unresolved],
         triggers: [{ id: 'trigger', executor: 'must-not-probe' }],
       }, {
+        models: ['allowed-model'],
+        modelRegistryPath: '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/project/flows.json',
         probes: {
           cli: () => { calls.push('cli'); return { exists: true, authenticated: true }; },
           command: () => { calls.push('command'); return true; },
@@ -492,19 +497,15 @@ describe('preflight: CLI resolution and refusal predicates', () => {
     expect(JSON.stringify(scenarios)).not.toContain('raw secret');
   });
 
-  it('reports every model and CLI static refusal on the same step', () => {
+  it('reports CLI resolution before evaluating model governance on the same step', () => {
     const result = preflight(
       flow({ id: 'a', type: 'agent', instruction: 'i', model: 'typo-model' }),
       { models: ['known-model'], modelRegistryPath: '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/project/flows.json', probes: probes() },
     );
 
-    expect(result.diagnostics.map((diagnostic) => diagnostic.kind)).toEqual([
-      'model_unknown',
-      'cli_unresolved',
-    ]);
+    expect(result.diagnostics.map((diagnostic) => diagnostic.kind)).toEqual(['cli_unresolved']);
     expect(result.diagnostics[0]).toMatchObject({
       stepId: 'a',
-      model: 'typo-model',
     });
   });
 
@@ -645,6 +646,7 @@ describe('preflight: CLI resolution and refusal predicates', () => {
       cli: 'claude',
       source: 'named',
       model: 'claude-sonnet-5',
+      modelSource: 'named',
     }]);
     // The probe still ran: model authority does not skip auth verification.
     expect(probeCalls).toBe(1);
@@ -675,6 +677,7 @@ describe('preflight: CLI resolution and refusal predicates', () => {
       cli: 'claude',
       source: 'step',
       model: 'claude-sonnet-5',
+      modelSource: 'step',
     }]);
     expect(probeCalls).toBe(1);
   });
diff --git a/packages/sdk/tests/verb-field-lint.test.ts b/packages/sdk/tests/verb-field-lint.test.ts
index 50c16cf2b..b4255713a 100644
--- a/packages/sdk/tests/verb-field-lint.test.ts
+++ b/packages/sdk/tests/verb-field-lint.test.ts
@@ -423,8 +423,8 @@ describe('closed per-verb step fields', () => {
     });
     expect(result.ok).toBe(true);
     expect(result.resolutions).toEqual([
-      { stepId: 'answer', cli: 'llm-cli', source: 'step', model: 'project-model' },
-      { stepId: 'act', cli: 'agent-cli', source: 'step', model: 'project-model' },
+      { stepId: 'answer', cli: 'llm-cli', source: 'step', model: 'project-model', modelSource: 'step' },
+      { stepId: 'act', cli: 'agent-cli', source: 'step', model: 'project-model', modelSource: 'step' },
     ]);
   });
 
diff --git a/packages/sdk/tests/worker-cli.test.ts b/packages/sdk/tests/worker-cli.test.ts
index 364166f5b..5819e8ec4 100644
--- a/packages/sdk/tests/worker-cli.test.ts
+++ b/packages/sdk/tests/worker-cli.test.ts
@@ -73,7 +73,7 @@ process.stdout.write(JSON.stringify({ type: 'result', result: 'default-model-ok'
     expect(result).toMatchObject({ exit_code: 0, stdout_tail: 'default-model-ok',
       tokens_input: 2, tokens_output: 1 });
     expect(JSON.parse(readFileSync(calls, 'utf8'))).toEqual([
-      '-p', '--dangerously-skip-permissions', '--model', 'claude-sonnet-4-6',
+      '-p', '--dangerously-skip-permissions', '--model', 'claude-opus-5',
       '--output-format', 'json', 'do the task',
     ]);
   });
diff --git a/testdata/flows.json b/testdata/flows.json
index 4692d4bc5..3396475ca 100644
--- a/testdata/flows.json
+++ b/testdata/flows.json
@@ -3,7 +3,6 @@
   "executors": ["agent-worker"],
   "models": [
     "claude-haiku-4-5-20251001",
-    "claude-sonnet-4-6",
     "claude-sonnet-5",
     "deterministic-test-stub",
     "test-model-v1"