rpi-propose

name	rpi-propose
description	Design a new feature or non-trivial change with tradeoffs — produce a design and behavioral spec. Use when user says 'add feature X', 'introduce mode Y', 'support Z', or proposes new functionality, even if they don't say 'propose'. Do NOT invoke for narrow tweaks (use rpi-plan) or open-ended exploration (use rpi-research).

Solution Design

Goal

Create a design document (.rpi/designs/) and behavioral spec (.rpi/specs/) for a given topic or research.

Auto-detect the mode from input:

• Focused decision (e.g., "should we use X or Y?") → quick investigation, trade-off analysis, write design+spec
• Complex feature (description or path to research doc) → thorough investigation, explore options, synthesize, write design+spec
• Updating existing design (path to existing design) → read it, understand what changed, propose updates in place
• Nothing provided → ask for input with brief examples of each mode

When the user approves the spec, suggest → /rpi:rpi-plan <design-path>.

Invariants

• Before drafting, search for prior designs and specs on this topic; decide whether to supersede or extend
• See the project's RPI Skill Contract for --ff / --grill semantics; both flags apply here and are mutually exclusive
• If a research doc is provided, read it and resolve its full artifact chain — warn if still draft or already complete
• Inherit upstream decisions: when a research doc (or any upstream artifact) is provided, extend the chain resolution above to collect every non-empty ## Decisions section from each artifact in the resolved chain. Render them in the new design under a ## Inherited Decisions heading, each block grouped under From <source-artifact-path>: and quoted verbatim, attributed to the artifact that recorded it — the true origin, not the immediate parent or hop depth, so each inherited decision names exactly one source. Keep ## Inherited Decisions (upstream, carried forward, with source) distinct from the design's own ## Decisions (commitments made at this stage). If the chain has no ## Decisions sections, omit ## Inherited Decisions entirely — never fabricate an empty or invented block.
• Investigate the codebase before proposing — ground decisions in evidence with file:line refs
• Get user buy-in on trade-offs before writing the design
• Link the design to upstream research via frontmatter
• Create a behavioral spec with 5-8 Given/When/Then scenarios describing user-observable behavior — scenarios must not reference internal structure (structs, file paths, function names); include a Constraints section for boundaries and an Out of Scope section. Name the spec file after its feature field (e.g., feature: rpi-status → rpi-status.md)
• Pre-lock slice audit: after drafting the design Components and before presenting the design/spec for approval, audit the drafted Components for internal coherence. For a design with ≥2 Components, spawn the read-only rpi-slice-audit subagent via the Task tool over the drafted Components + any upstream research (slice-kind components); it runs the deterministic pre-lock coverage check — every ## File Structure entry is introduced by some Component and vice-versa — and adds cross-Component file/symbol mismatch and within-design decision-drift (a Component contradicting a Decision recorded in an earlier Component). For a single-Component design, run only the inline deterministic pre-lock coverage check. Surface findings at the approval gate with the same mode semantics as rpi-plan: interactive — blocking, resolve or waive each before approval; --ff — record findings and proceed, unless a hard coverage failure (a Component or ## File Structure entry mapping to no work), which blocks even under --ff; --grill — run the audit before grill-me so grilling operates on already-audited Components.
• Present the spec for approval — iterate until accepted
• Under --ff, skip the trade-off buy-in, the mid-flight decision checkpoints, and the spec approval gate — auto-accept the drafted design and spec and immediately invoke /rpi:rpi-plan --ff <design-path> via the Skill tool
• Under --grill (or matching natural-language phrasing) and when grill-me is available, invoke grill-me on the drafted design+spec before the approval gate; apply revisions inline. If grill-me is unavailable, tell the user and ask whether to proceed with the standard approval gate.
• Transition artifacts: design → active, research → complete (if fully addressed)
• For incremental mode: update in place, add an Update Log entry, update affected specs

Principles

• Be opinionated — recommend with clear reasoning grounded in codebase evidence
• Be interactive — checkpoint before major decisions; a design that surprises during review means the process failed
• Scale effort to complexity — a focused decision needs less investigation than a new subsystem
• Specs are the contract — every design culminates in a spec
• Grilling is opt-in and single-pass — re-invoke if a second round is needed

Recommended model: premium tier, high effort — tradeoff analysis and spec authoring are the hardest reasoning. Advisory; see docs/model-routing.md.