JuliusBrussee/caveman · error · Error

cave_claude_provider_unsupported

Error message

cave_claude_provider_unsupported

What it means

resolveClaudeModel() resolved a model string but its provider prefix is not "anthropic" (or there is no "provider/model" separator at position >= 1). The Claude harness only speaks the Anthropic provider, so models like "openai/gpt-4o" or malformed strings like "/claude-haiku" are rejected before the SDK call.

Source

Thrown at packages/agent/src/claude-runtime.ts:471

  const target = name.toLowerCase();
  const kept = (raw ?? "").split(/\r\n|\n|\r/).filter((line) => {
    if (!line.trim()) return false;
    const colon = line.indexOf(":");
    return (colon < 0 ? line : line.slice(0, colon)).trim().toLowerCase() !== target;
  });
  kept.push(`${name}: ${value}`);
  return kept.join("\n");
}

function resolveClaudeModel(definition: AgentDefinition, rootDir: string): string {
  const configured = typeof definition.model === "string"
    ? definition.model
    : process.env.CAVE_MODEL ?? localModel(rootDir) ??
      (process.env.ANTHROPIC_API_KEY ? "anthropic/claude-haiku-4-5" : undefined);
  if (configured === undefined) throw new Error("cave_claude_model_required");
  const separator = configured.indexOf("/");
  if (separator < 1 || configured.slice(0, separator) !== "anthropic") {
    throw new Error("cave_claude_provider_unsupported");
  }
  return normalizeClaudeModel(configured.slice(separator + 1));
}

function localModel(rootDir: string): string | undefined {
  try {
    const parsed = JSON.parse(readFileSync(resolve(rootDir, ".caveman/provider.json"), "utf8")) as {
      model?: unknown;
    };
    return typeof parsed.model === "string" ? parsed.model : undefined;
  } catch (error) {
    if ((error as NodeJS.ErrnoException).code === "ENOENT") return undefined;
    throw new Error("caveman agent: invalid .caveman/provider.json");
  }
}

function normalizeClaudeModel(model: string): string {
  return model.startsWith("anthropic/") ? model.slice("anthropic/".length) : model;

View on GitHub (pinned to 27d5a3981a)

Solutions

1. Rewrite the model id with the anthropic prefix: "anthropic/claude-haiku-4-5".
2. If you actually want a non-Anthropic model, select the harness/adapter that supports that provider instead of the Claude one.
3. Add a config-time lint that model strings for the Claude lane match /^anthropic\/.+/.

Example fix

// before
const definition = { id: "x", model: "openai/gpt-4o-mini" };

// after
const definition = { id: "x", model: "anthropic/claude-haiku-4-5" };

function isAnthropicModelRoute(model: string): boolean {
  const sep = model.indexOf("/");
  return sep >= 1 && model.slice(0, sep) === "anthropic";
}

When it happens

Trigger: definition.model / CAVE_MODEL / provider.json model set to a non-Anthropic route ("openai/...", "google/...", "groq/..."), a bare model with no slash ("claude-haiku-4-5"), or a leading slash ("/claude-haiku-4-5" makes separator index 0 < 1).

Common situations: Copying a model string from another harness's config (the framework supports pi/vercel-ai-sdk lanes that use openrouter-style ids); switching a project from an OpenAI provider to the Claude harness without rewriting the model id; typo like "anthropic:" instead of "anthropic/".

Related errors

• cave_claude_model_required
• cave_vercel_terminal_failure
• cave_breaker_threshold_invalid
• cave_breaker_retry_requires_budget
• cave_breaker_retry_spend_invalid

AI-assisted analysis of JuliusBrussee/caveman@27d5a3981a (2026-08-15). Data as JSON: /api/errors/dcae21f662ee14dd. Report an issue: GitHub.