chore: sync .cursor skills from suite

.cursor/skills/research/steps/02_mode-b-solution-assessment.md

@@ -10,18 +10,25 @@ Full 8-step research methodology applied to assessing and improving an existing
 
 **Task** (drives the 8-step engine):
 1. Read the existing solution draft thoroughly
-2. Research in internet extensively — for each component/decision in the draft, search for:
+2. Derive or refresh the **Project Constraint Matrix** from all files in INPUT_DIR. Include required inputs/outputs, operating context, runtime envelope, data availability, lifecycle boundaries, non-functional targets, integration boundaries, security constraints, and explicit out-of-scope decisions.
+3. Audit every component/decision in the existing draft against the Project Constraint Matrix before researching alternatives:
+   - If a component's documented implementation assumptions match the project constraints, keep it eligible and record evidence.
+   - If fit is unproven, mark it `Experimental only` until evidence is found.
+   - If constraints conflict, mark it `Rejected` and search for alternatives.
+   - If rejecting it changes product behavior or risk materially, escalate for user decision.
+4. Research in internet extensively — for each component/decision in the draft, search for:
    - Known problems and limitations of the chosen approach
    - What practitioners say about using it in production
    - Better alternatives that may have emerged recently
    - Common failure modes and edge cases
    - How competitors/similar projects solve the same problem differently
-3. Search specifically for contrarian views: "why not [chosen approach]", "[chosen approach] criticism", "[chosen approach] failure"
-4. Identify security weak points and vulnerabilities — search for CVEs, security advisories, and known attack vectors for each technology in the draft
-5. Identify performance bottlenecks — search for benchmarks, load test results, and scalability reports
-6. For each identified weak point, search for multiple solution approaches and compare them
-7. Based on findings, form a new solution draft in the same format
+5. Search specifically for contrarian views: "why not [chosen approach]", "[chosen approach] criticism", "[chosen approach] failure"
+6. Identify security weak points and vulnerabilities — search for CVEs, security advisories, and known attack vectors for each technology in the draft
+7. Identify performance bottlenecks — search for benchmarks, load test results, and scalability reports
+8. For each identified weak point, search for multiple solution approaches and compare them
+9. For every revised candidate, prove exact fit against the Project Constraint Matrix. Do not select field-adjacent or "similar problem" options unless their intrinsic implementation constraints match the project.
+10. Based on findings, form a new solution draft in the same format
 
-**Save action**: Write `OUTPUT_DIR/solution_draft##.md` (incremented) using template: `templates/solution_draft_mode_b.md`
+**Save action**: Write `RESEARCH_DIR/06_component_fit_matrix.md` before the final draft, then write `OUTPUT_DIR/solution_draft##.md` (incremented) using template: `templates/solution_draft_mode_b.md`
 
 **Optional follow-up**: After Mode B completes, the user can request Phase 3 (Tech Stack Consolidation) or Phase 4 (Security Deep Dive) using the revised draft. These phases work identically to their Mode A descriptions in `steps/01_mode-a-initial-research.md`.