Trait Pack

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pub trait Pack: Send + Sync {
    // Required methods
    fn name(&self) -> &'static str;
    fn register(&self, host: &Arc<Host>, registry: &mut Registry);
    fn preamble(&self, ctx: &PackContext) -> Vec<Message>;

    // Provided methods
    fn required_api_schemas(&self) -> Option<&'static [&'static str]> { ... }
    fn shape_user_prompt(&self, text: &str) -> String { ... }
    fn build_registry(&self, host: &Arc<Host>) -> Registry { ... }
}

Expand description

A faithful reproduction of one harness: its real toolset + its base prompt, selected whole via --harness (ADR-0012). One pack is active per run.

The pack — not a per-tool field — is the unit of harness identity (contrast Grok Build, which tags every tool with a namespace because it co-locates all harnesses’ tools in one registry; we build a fresh registry per pack, so no tag is needed).

Required Methods§

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fn name(&self) -> &'static str

The --harness selector and the report-envelope harness value.

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fn register(&self, host: &Arc<Host>, registry: &mut Registry)

Register this pack’s tools into registry, each under its harness’s real wire name (Tool has no name of its own — the name is assigned here). Tools are constructed here holding an Arc<Host> (the only OS seam; ToolCtx is too small to carry it). A duplicate name is a wiring bug and panics inside Registry::register.

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fn preamble(&self, ctx: &PackContext) -> Vec<Message>

The pack’s base preamble: the ordered, role-tagged System/Developer messages that seed the conversation (ADR-0013). Each pack maps its harness onto our roles faithfully — a single System message, or System + Developer, etc. The wire (Task 12) places each role in the right slot. Task 8 ships a scaffold; the real content lands in Task 13.

Provided Methods§

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fn required_api_schemas(&self) -> Option<&'static [&'static str]>

The provider wire schemas this pack’s tools require, or None when the pack is wire-agnostic (grok, claude). The codex pack pins ["openai-responses"] because its apply_patch is a freeform (custom-grammar) tool that only round-trips on the OpenAI Responses wire (ADR-0012, D5). Checked pre-run against the resolved provider: a real schema not in the set fails before the loop with an actionable message. The mock wire (keyless CI) is a universal escape hatch and is always allowed, independent of this list.

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fn shape_user_prompt(&self, text: &str) -> String

Shape a raw user prompt the way this harness expects it. Some harnesses wrap the task in a tag their system prompt refers to (grok’s <user_query>); Claude Code sends it verbatim. The default is verbatim; a pack overrides only if its prompt is written against a wrapper. Keeps harness-specific shaping in the pack rather than spread across the exec/tui layers.

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