feat: skill-specific Search Before Building integrations

8 template changes:
- /office-hours: Phase 2.75 Landscape Awareness (WebSearch + three-layer synthesis)
- /plan-eng-review: Step 0 search check with layer provenance annotations
- /investigate: external pattern search + search escalation on hypothesis failure
- /plan-ceo-review: Landscape Check before scope challenge
- /review: search-before-recommending for fix patterns
- /qa-only: WebSearch in allowed-tools
- /design-consultation: three-layer synthesis backport in Phase 2 Step 3
- /retro: eureka moment tracking from ~/.gstack/analytics/eureka.jsonl

All search steps include WebSearch fallback clause.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

office-hours/SKILL.md

@@ -19,6 +19,7 @@ allowed-tools:
   - Write
   - Edit
   - AskUserQuestion
+  - WebSearch
 ---
 <!-- AUTO-GENERATED from SKILL.md.tmpl — do not edit directly -->
 <!-- Regenerate: bun run gen:skill-docs -->
@@ -476,6 +477,37 @@ If no matches found, proceed silently.
 
 ---
 
+## Phase 2.75: Landscape Awareness
+
+Read ETHOS.md for the full Search Before Building framework (three layers, eureka moments). The preamble's Search Before Building section has the ETHOS.md path.
+
+After understanding the problem through questioning, search for what the world thinks. This is NOT competitive research (that's /design-consultation's job). This is understanding conventional wisdom so you can evaluate where it's wrong.
+
+If WebSearch is unavailable, skip this phase and note: "Search unavailable — proceeding with in-distribution knowledge only."
+
+**Startup mode:** WebSearch for:
+- "[problem space] startup approach {current year}"
+- "[problem space] common mistakes"
+- "why [incumbent solution] fails" OR "why [incumbent solution] works"
+
+**Builder mode:** WebSearch for:
+- "[thing being built] existing solutions"
+- "[thing being built] open source alternatives"
+- "best [thing category] {current year}"
+
+Read the top 2-3 results. Run the three-layer synthesis:
+- **[Layer 1]** What does everyone already know about this space?
+- **[Layer 2]** What are the search results and current discourse saying?
+- **[Layer 3]** Given what WE learned in Phase 2A/2B — is there a reason the conventional approach is wrong?
+
+**Eureka check:** If Layer 3 reasoning reveals a genuine insight, name it: "EUREKA: Everyone does X because they assume [assumption]. But [evidence from our conversation] suggests that's wrong here. This means [implication]." Log the eureka moment (see preamble).
+
+If no eureka moment exists, say: "The conventional wisdom seems sound here. Let's build on it." Proceed to Phase 3.
+
+**Important:** This search feeds Phase 3 (Premise Challenge). If you found reasons the conventional approach fails, those become premises to challenge. If conventional wisdom is solid, that raises the bar for any premise that contradicts it.
+
+---
+
 ## Phase 3: Premise Challenge
 
 Before proposing solutions, challenge the premises:

office-hours/SKILL.md.tmpl

@@ -19,6 +19,7 @@ allowed-tools:
   - Write
   - Edit
   - AskUserQuestion
+  - WebSearch
 ---
 
 {{PREAMBLE}}
@@ -235,6 +236,37 @@ If no matches found, proceed silently.
 
 ---
 
+## Phase 2.75: Landscape Awareness
+
+Read ETHOS.md for the full Search Before Building framework (three layers, eureka moments). The preamble's Search Before Building section has the ETHOS.md path.
+
+After understanding the problem through questioning, search for what the world thinks. This is NOT competitive research (that's /design-consultation's job). This is understanding conventional wisdom so you can evaluate where it's wrong.
+
+If WebSearch is unavailable, skip this phase and note: "Search unavailable — proceeding with in-distribution knowledge only."
+
+**Startup mode:** WebSearch for:
+- "[problem space] startup approach {current year}"
+- "[problem space] common mistakes"
+- "why [incumbent solution] fails" OR "why [incumbent solution] works"
+
+**Builder mode:** WebSearch for:
+- "[thing being built] existing solutions"
+- "[thing being built] open source alternatives"
+- "best [thing category] {current year}"
+
+Read the top 2-3 results. Run the three-layer synthesis:
+- **[Layer 1]** What does everyone already know about this space?
+- **[Layer 2]** What are the search results and current discourse saying?
+- **[Layer 3]** Given what WE learned in Phase 2A/2B — is there a reason the conventional approach is wrong?
+
+**Eureka check:** If Layer 3 reasoning reveals a genuine insight, name it: "EUREKA: Everyone does X because they assume [assumption]. But [evidence from our conversation] suggests that's wrong here. This means [implication]." Log the eureka moment (see preamble).
+
+If no eureka moment exists, say: "The conventional wisdom seems sound here. Let's build on it." Proceed to Phase 3.
+
+**Important:** This search feeds Phase 3 (Premise Challenge). If you found reasons the conventional approach fails, those become premises to challenge. If conventional wisdom is solid, that raises the bar for any premise that contradicts it.
+
+---
+
 ## Phase 3: Premise Challenge
 
 Before proposing solutions, challenge the premises: