Rulebook library: Generate project-scope rovodev prompts.yml for skill delivery

[williamthorsen]

Parent: #576 · Depends on: #732 (S2 skill delivery)

Problem

Rovo Dev discovers skills through a generated prompts.yml index, not by walking directories. S2 (#732) writes thin-wrapper rulebook skills into the project-local .rovodev/skills/ directory, but sync produces no project-scope prompts.yml, so those skills are not discoverable by Rovo Dev. The files are written but inert.

Context

install already generates a home-scope prompts.yml via generatePromptsYml in packages/agents/src/commands/install.ts. That function is coupled to install's manifest and drift machinery (ManifestEntry, drift detection, install options) and writes to the platform home. sync needs the same index built from the project-local .rovodev/skills/ directory and written to {projectRoot}/.rovodev/prompts.yml.

Proposed solution

Reuse the existing prompts.yml generation. If the current generatePromptsYml cannot be reused directly because it is coupled to install's manifest/drift flow, extract its core — scan a skills directory for user-invocable skills and render the prompts.yml content — into a shared helper that both install and sync call, leaving no duplicated rendering logic. sync then writes and updates {projectRoot}/.rovodev/prompts.yml whenever rovodev is a targeted platform, idempotently, keeping entries in step as rulebook skills are added or retracted.

A design decision for this ticket: whether sync owns the entire project-scope prompts.yml or merges its rulebook-skill entries with any hand-authored ones, mirroring the marker-based ownership used for the skill files themselves.

Acceptance criteria

Must have

• When rovodev is a targeted platform, sync generates and updates {projectRoot}/.rovodev/prompts.yml listing the rulebook skills it installs.
• The prompts.yml content generation is shared with install — reused directly, or extracted into a common helper when direct reuse is not possible — with no duplicated rendering logic.
• Re-running sync with unchanged content does not rewrite prompts.yml (idempotent).
• Retracting a rulebook skill removes its prompts.yml entry.
• New and changed behavior in this change is covered by tests.