coleam00/Archon · error · Error

--resume and --model are mutually exclusive. A resumed run k

Error message

--resume and --model are mutually exclusive. A resumed run keeps its original model bindings.

What it means

The CLI refuses to combine `--resume` with `--model`: a continued run inherits the model assignments recorded at its original start, and re-binding models mid-resume is unsupported. This is a hard argument-conflict check on the programmatic boundary (`workflowRunCommand`).

Source

Thrown at packages/cli/src/commands/workflow.ts:1671

  // id crossed between two concurrent detached launches, and the narrow window where the
  // child's re-capture resolves a different workflow than the parent did.
  if (detachedPreCreatedRun && detachedPreCreatedRun.workflow_name !== workflow.name) {
    throw new Error(
      `Cannot execute run '${detachedPreCreatedRun.id}': it belongs to workflow ` +
        `'${detachedPreCreatedRun.workflow_name}', not '${workflow.name}'.`
    );
  }

  // Keys this workflow's YAML declares that the engine drops (#2213). Written to
  // stderr, never stdout: in --json mode Pino is silenced and stdout must stay
  // exactly the machine-readable payload, so this is the ONLY channel that
  // reaches an agent driving runs through `--json`. Not gated on --quiet — a
  // dropped key can be a gate the author believes is protecting the run.
  emitParseWarnings(workflowEntry?.parseWarnings, workflow.name);
  emitDeprecationNotice(workflow);

  if (isContinuation && options.modelAssignments && options.modelAssignments.length > 0) {
    throw new Error(
      '--resume and --model are mutually exclusive. A resumed run keeps its original model bindings.'
    );
  }

  const dryRunOnlyOptions = [
    ['--stubs', options.stubsPath !== undefined],
    ['--stubs-init', options.stubsInitPath !== undefined],
    ['--default-stubs', options.defaultStubs === true],
    ['--exec-code', options.execCode === true],
    ['--pause-at-gates', options.pauseAtGates === true],
  ] as const;
  const optionWithoutDryRun = dryRunOnlyOptions.find(([, present]) => present)?.[0];
  if (!options.dryRun && optionWithoutDryRun) {
    throw new Error(`${optionWithoutDryRun} requires --dry-run.`);
  }

  if (options.dryRun) {
    const incompatible = [

View on GitHub (pinned to 0773b97458)

Solutions

1. Drop the --model flags and re-run with --resume only; the run keeps its original model bindings
2. If a different model is genuinely needed, start a NEW run with --model instead of resuming

Example fix

// before
archon workflow run wf --resume run-123 --model agent=opus
// after
archon workflow run wf --resume run-123

if (isResume && modelFlags.length > 0) {
  throw new Error('--resume and --model are mutually exclusive');
}

try {
  await runWorkflow(args);
} catch (e) {
  if (/mutually exclusive/.test(String(e.message))) {
    args = args.filter(a => !a.startsWith('--model'));
    return runWorkflow(args);
  }
  throw e;
}

When it happens

Trigger: `archon workflow run <wf> --resume <run> --model node=model` or calling workflowRunCommand with both isContinuation and non-empty options.modelAssignments.

Common situations: Wanting to change models when resuming after a failure; a script that appends `--model` flags unconditionally and is then reused for a resume.

Understand the failure class

Background: "mutually exclusive" flag errors: what "can't supply both nx and xx", "--raw is not compatible with -i" and "cannot be used with" mean, and how to fix them — this error's family across 29 libraries.

Related errors

• --dry-run cannot be combined with ${incompatibleFlag}.
• --stubs-init cannot be combined with --stubs.
• --stubs-init cannot be combined with --default-stubs.
• --branch and --no-worktree are mutually exclusive. --branc
• --from/--from-branch has no effect with --no-worktree. Remov

AI-assisted analysis of coleam00/Archon@0773b97458 (2026-09-01). Data as JSON: /api/errors/04a5af0638e9d29e. Report an issue: GitHub.