docs: define contribution scope and simplify proposal forms

Define REA contribution scope and fail closed on unresolved integration boundaries.

Make proposal forms easier to complete with structured choices, explicit unknowns, and optional technical details; welcome exploratory drafts while retaining maintainer review before integration.

.github/pull_request_template.md

@@ -19,17 +19,39 @@ describe the use case and observable outcome. -->
 <!-- Explain the chosen approach, why it fits REA's architecture, and what is
 intentionally not included. -->
 
+Follow the [contribution scope](https://github.com/morluto/rea/blob/main/CONTRIBUTING.md#contribution-scope).
+Unresolved scope, authority, side effects, or required verification block
+integration. Link the required maintainer scope decision for new providers or
+capabilities involving target execution, injection, mutation, or protection
+recovery; ordinary fixes within existing boundaries may state "not applicable".
+Draft PRs may leave the scope decision pending and the final review checklist
+unchecked. Maintainers can help resolve open questions.
+
 ## Contract and boundary impact
 
-<!-- Complete the applicable lines; use "none" or "not applicable" explicitly. -->
+<!-- Short answers are welcome. Complete applicable lines; mark unresolved facts as "unknown".
+Use "none" or "not applicable" only when established. -->
 
 - Semantic owner and earliest changed stage:
+- Contribution scope fit and linked maintainer decision:
 - CLI and MCP/tool-catalog contract:
 - Provider, bridge, target-format, or platform compatibility:
 - Evidence, artifact, provenance, or reconstruction contract:
-- Process execution, authorization, cleanup, or containment impact:
+- Target selection, authority, upstream behavior, and cleanup details (if applicable):
 - Generated metadata (`docs/public/product-catalog.json`), package, or installation impact (CI generates and validates ignored catalogs and `skills/`; edit authored instructions in `.agents/skills/reverse-engineer-anything/` and never commit build outputs):
 
+Expected effects (check known effects; use documentation-only on its own).
+Unchecked items do not establish absence; leave uncertainties visible.
+
+- [ ] Read existing files or captured data.
+- [ ] Launch or attach to a process.
+- [ ] Inject instrumentation or run scripts/code.
+- [ ] Change process memory, registers, files, or configuration.
+- [ ] Contact network services.
+- [ ] Recover protected code or work around protections.
+- [ ] Documentation or usability only; no target interaction.
+- [ ] Not sure yet; investigation or maintainer guidance needed.
+
 ## Evidence and regression coverage
 
 <!-- State whether evidence is executed, source-derived, or proposed. For fixes,
@@ -68,9 +90,13 @@ limits, security/privacy/containment implications, and meaningful proof gaps. --
 - Package or release metadata impact:
 - Security, privacy, process, or containment review:
 
-## Review checklist
+## Before merge
+
+<!-- Draft PRs may leave pending items unchecked. Resolve material scope and
+authority questions before integration. -->
 
 - [ ] This PR addresses a concrete problem or an agreed enhancement.
+- [ ] Material scope and authority questions are resolved, and any required maintainer scope decision covers the final diff.
 - [ ] The PR has one focused outcome and the title follows `type(scope): outcome`.
 - [ ] Related issue is linked, or the reason for not linking one is stated above.
 - [ ] Tests cover changed observable behavior and meaningful failure paths.