# How cavecrew-builder Signals “too-big” or “ambiguous” Tasks in Caveman > Learn how cavecrew-builder signals too-big or ambiguous tasks with terminal refusal lines, enabling parent agents to split work or seek clarification efficiently. - Repository: [Julius Brussee/caveman](https://github.com/JuliusBrussee/caveman) - Tags: deep-dive - Published: 2026-07-12 --- **The `cavecrew-builder` agent outputs terminal refusal lines—`too-big. split: one-line tasks.` for oversized requests and `ambiguous. ask: .` for unclear instructions—allowing parent agents to split work or request clarification instead of guessing.** The `cavecrew-builder` is a specialized sub-agent in the JuliusBrussee/caveman repository designed to execute minimal, surgical edits across one or two files. When it encounters a task that exceeds its narrow scope or lacks sufficient detail, it does not attempt partial execution or guesswork; instead, it emits structured refusal tokens that the parent orchestrator can parse and act upon. ## Terminal Refusal Tokens Defined in cavecrew-builder.md The signalling mechanism is contract-based. The parent agent expects specific string prefixes that indicate terminal failure states, allowing the orchestration layer to decide whether to split the task, prompt the user, or abort. ### The “too-big” Signal When a request touches **three or more files**, the builder immediately halts and returns: ``` too-big. split: . ``` This token indicates the task violates the builder’s **1-2 file limit** and suggests dividing the work into *n* separate single-line tasks. The parent agent can parse the integer and automatically generate new sub-tasks for each file. ### The “ambiguous” Signal When instructions are unclear, incomplete, or lacking context, the builder responds with: ``` ambiguous. ask: . ``` This signals that the builder cannot determine the correct operation and requires a specific clarifying question to proceed. The parent agent typically routes this question to the user or to a clarification sub-agent. ## Implementation in the Source Code According to the source code in [`agents/cavecrew-builder.md`](https://github.com/JuliusBrussee/caveman/blob/main/agents/cavecrew-builder.md) (lines 38-44), these tokens are defined under the **“Refusals (terminal lines)”** section. The complete set of terminal refusal tokens includes: - `too-big.` - `ambiguous.` - `needs-confirm.` - `regressed.` When the builder outputs any of these lines, it terminates immediately without printing a diff or attempting file modifications. This **fail-fast** behavior prevents partial edits and preserves token efficiency. ## Code Examples from the Repository The refusal logic manifests in the agent’s execution flow as simple conditional checks: ```javascript // Example: Builder detects a 4-file request if (files.length >= 3) { // Returns a refusal line the parent can parse console.log('too-big. split: 4 one-line tasks.'); } ``` ```javascript // Example: Builder cannot infer the operation if (!isClear(request)) { console.log('ambiguous. ask: Which function should I refactor?'); } ``` In practice, the builder never prints a normal diff when it hits these cases; it immediately outputs the refusal line, which the orchestrating code treats as a terminal response. ## How Parent Agents Handle These Signals The `cavecrew-investigator` and the main Caveman orchestrator monitor the builder’s stdout for these exact string prefixes. Upon detecting `too-big.`, the parent may invoke a task-splitting strategy. Upon detecting `ambiguous.`, it can surface the embedded question to the user via the UI or CLI. ## Key Files in the Caveman Ecosystem - **[`agents/cavecrew-builder.md`](https://github.com/JuliusBrussee/caveman/blob/main/agents/cavecrew-builder.md)**: Defines the builder’s scope, workflow, output receipt format, and the exact refusal tokens. - **[`skills/cavecrew/SKILL.md`](https://github.com/JuliusBrussee/caveman/blob/main/skills/cavecrew/SKILL.md)**: High-level description of the cavecrew family, reiterating the refusal tokens for consistency across sub-agents. - **[`agents/cavecrew-investigator.md`](https://github.com/JuliusBrussee/caveman/blob/main/agents/cavecrew-investigator.md)**: Consumes the builder’s refusal lines and decides whether to split the task or ask the user for clarification. ## Summary - `cavecrew-builder` outputs `too-big. split: one-line tasks.` when requests touch **≥3 files**, violating its 1-2 file constraint. - It outputs `ambiguous. ask: .` when instructions are unclear or lack necessary context. - These tokens are defined in [`agents/cavecrew-builder.md`](https://github.com/JuliusBrussee/caveman/blob/main/agents/cavecrew-builder.md) under **“Refusals (terminal lines)”** and act as terminal responses. - Parent agents detect these exact strings to determine next steps without parsing complex error objects or stack traces. ## Frequently Asked Questions ### What is the file limit for cavecrew-builder before it triggers “too-big”? The builder is designed for **1-2 file edits**. When a task touches three or more files, it emits the `too-big.` refusal token and suggests splitting the work into separate one-line tasks. ### Where are the refusal tokens defined in the source code? The exact refusal strings are documented in [`agents/cavecrew-builder.md`](https://github.com/JuliusBrussee/caveman/blob/main/agents/cavecrew-builder.md) under the **“Refusals (terminal lines)”** section, specifically lines 38-44. The file also defines the builder’s scope constraints and workflow. ### Can cavecrew-builder attempt part of a large task anyway? No. When the builder encounters a scope violation or ambiguity, it immediately outputs the refusal line and terminates without attempting partial execution, generating a diff, or modifying any files. ### How does the parent agent know when to ask the user for clarification? The parent agent watches for the `ambiguous. ask:` prefix in the builder’s output. When detected, it extracts the question following the prefix and can present it to the user to resolve the ambiguity before retrying the task.