Arch review

<Purpose> Review RTL architecture for consistency with the microarchitecture spec, timing feasibility, and code quality. All agents operate READ-ONLY — no modifications are made. Outputs: reviews/phase-2-architecture/architecture-review.md with findings per reviewer.

Note: This skill intentionally saves to reviews/phase-2-architecture/ because it re-validates the Phase 2 architecture after RTL implementation. It updates (not replaces) the existing Phase 2 review artifacts with post-RTL findings per Hierarchical Spec Compliance. </Purpose>

<Use_When>

• RTL implementation is complete and needs architecture sign-off
• Microarchitecture spec (docs/phase-3-uarch/*.md) exists for comparison
• Pre-tapeout architecture review gate
• Suspecting architectural mismatch after late RTL changes </Use_When>

<Do_Not_Use_When>

• RTL is not yet lint-clean (fix lint first with rtl-lint-check)
• Only functional bugs need diagnosis (use rtl-bug-repro instead)
• Architecture changes are also requested (arch-review is READ-ONLY) </Do_Not_Use_When>

<Why_This_Exists> Architecture review catches structural mismatches between spec and implementation that functional tests cannot detect. Three independent reviewers with different focus areas (structure, timing, quality) provide broader coverage than a single pass. </Why_This_Exists>

<Execution_Policy>

• All three agents run in parallel, READ-ONLY
• rtl-architect checks spec-to-RTL consistency
• timing-advisor checks pipeline depth, clock domain structure, timing feasibility
• rtl-critic checks code quality, maintainability, synthesis-friendliness
• Findings aggregated into single report — no RTL changes </Execution_Policy>

<Steps> 1. Read docs/phase-1-research/iron-requirements.json, docs/phase-3-uarch/*.md, and rtl/*/*.sv to pass context 2. `mkdir -p reviews/phase-2-architecture` 3. Run three agents in parallel (all READ-ONLY): a. rtl-architect: spec vs RTL structure review **+ docs/phase-1-research/iron-requirements.json full coverage check** b. timing-advisor: pipeline and timing feasibility review c. rtl-critic: code quality and synthesis review 4. **rtl-architect produces a Feature Coverage Checklist (MANDATORY output):** - Read docs/phase-1-research/iron-requirements.json and check every REQ-NNN item against RTL implementation - Per-requirement status: ``` REQ-001: implemented in cabac_encoder.sv — COVERED REQ-002: implemented in input_buffer.sv — COVERED REQ-005: NOT FOUND in any RTL module — MISSING REQ-008: partially implemented in transform.sv (missing edge case) — PARTIAL ``` - Summary verdict: ``` VERDICT: PASS — all [N] requirements covered in RTL ``` or: ``` VERDICT: FAIL — [M] of [N] requirements have spec violations MISSING: REQ-005, REQ-012 PARTIAL: REQ-008 ``` 5. Aggregate findings into `reviews/phase-2-architecture/architecture-review.md` 6. **Ensure review result is saved in standard review Markdown format:** - If the file already exists (from Phase 2 Quality Gate), update it with the latest review results - Format: ```markdown # Phase 2 Review: Architecture Review - Date: YYYY-MM-DD - Reviewer: rtl-architect, timing-advisor, rtl-critic - Upper Spec: docs/phase-1-research/iron-requirements.json, docs/phase-3-uarch/*.md - Verdict: PASS | FAIL

 ## Feature Coverage Checklist
 | REQ ID | RTL Module | Status |
 |--------|-----------|--------|

 ## Findings
 ### [severity] Finding-N: ...

 ## Verdict
 PASS | FAIL: [reason]
 ```

7. Categorize issues: BLOCKER / WARN / SUGGESTION

• Any MISSING requirement is automatically a BLOCKER
• Any PARTIAL requirement is at minimum a WARN </Steps>

<Tool_Usage>

Bash("mkdir -p reviews/phase-2-architecture")

Task(subagent_type="rtl-agent-team:rtl-architect",
     prompt="READ-ONLY review. (1) Read docs/phase-1-research/iron-requirements.json and check every REQ-NNN item for implementation in rtl/. Produce a Feature Coverage Checklist with per-REQ status: COVERED, PARTIAL, or MISSING. (2) Compare docs/phase-3-uarch/*.md against rtl/. List any spec-RTL mismatches, missing modules, or unspecified additions. Verify port naming follows project convention: i_ prefix for inputs, o_ prefix for outputs, io_ prefix for bidirectional. Save the review result to reviews/phase-2-architecture/architecture-review.md in standard review Markdown format with Date, Reviewer (rtl-architect, timing-advisor, rtl-critic), Upper Spec (docs/phase-1-research/iron-requirements.json, docs/phase-3-uarch/*.md), Verdict, Feature Coverage Checklist table, Findings, and Verdict sections. If the file already exists, update it with the latest review results. Output final verdict: VERDICT: PASS or VERDICT: FAIL — [N] spec violations found.")

Task(subagent_type="rtl-agent-team:timing-advisor",
     prompt="READ-ONLY review. Analyze rtl/ pipeline depth, clock domains ({domain}_clk naming, e.g. sys_clk), and reset strategy ({domain}_rst_n naming, e.g. sys_rst_n). Flag timing feasibility concerns and any clock/reset naming violations.")

Task(subagent_type="rtl-agent-team:rtl-critic",
     prompt="READ-ONLY review. Assess rtl/ code quality: synthesizability, coding style (lowRISC base with project overrides: i_/o_/io_ port prefixes, {domain}_clk/{domain}_rst_n naming, logic only, u_ instance prefix, gen_ generate prefix), maintainability. List issues with severity.")

</Tool_Usage>

<Coding_Convention_Requirements> Reviewers must verify these project-specific conventions (overrides lowRISC defaults):

• Port prefixes: i_ (input), o_ (output), io_ (bidirectional) — NOT suffix _i/_o
• Clock naming: clk (single domain) or {domain}_clk (multiple domains, e.g., sys_clk) — NOT clk_i
• Reset naming: rst_n (single domain) or {domain}_rst_n (multiple domains, e.g., sys_rst_n) — NOT rst_ni
• Data types: logic only — reg/wire forbidden
• Instance prefix: u_ (e.g., u_fifo) — generate prefix: gen_
• Any deviation from these conventions is at minimum a WARN finding </Coding_Convention_Requirements>

<Examples> <Good> Three parallel reviews complete; rtl-architect finds missing error-handling state in FSM (BLOCKER); timing-advisor flags 7-stage pipeline exceeding timing budget (WARN); rtl-critic notes inconsistent reset polarity (WARN). All reported in reviews/phase-2-architecture/architecture-review.md, no RTL touched. </Good> <Bad> Having rtl-architect also fix the issues it finds — mixing review with implementation defeats the READ-ONLY audit purpose. </Bad> </Examples>

<Escalation_And_Stop_Conditions>

• BLOCKER found → surface immediately to user before completing report
• Spec document missing → halt, inform user that docs/phase-3-uarch/*.md is required
• Conflicting findings between reviewers → include both perspectives in report </Escalation_And_Stop_Conditions>

<Final_Checklist>

• All three agents ran READ-ONLY with no file modifications
• reviews/phase-2-architecture/architecture-review.md written with findings per reviewer
• Feature Coverage Checklist included with per-REQ-NNN status
• rtl-architect verdict output: VERDICT: PASS or VERDICT: FAIL — [N] spec violations found
• Any MISSING requirement categorized as BLOCKER
• Issues categorized as BLOCKER / WARN / SUGGESTION
• BLOCKERs highlighted prominently in report
• reviews/phase-2-architecture/architecture-review.md saved (or updated) with review result </Final_Checklist>