diff --git a/autoplan/SKILL.md b/autoplan/SKILL.md
index b84089926..0f43b55fe 100644
--- a/autoplan/SKILL.md
+++ b/autoplan/SKILL.md
@@ -357,6 +357,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/codex/SKILL.md b/codex/SKILL.md
index 95dcf1135..1e7148300 100644
--- a/codex/SKILL.md
+++ b/codex/SKILL.md
@@ -353,6 +353,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/design-consultation/SKILL.md b/design-consultation/SKILL.md
index 5aff1b9e1..9024d85cb 100644
--- a/design-consultation/SKILL.md
+++ b/design-consultation/SKILL.md
@@ -376,6 +376,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/design-review/SKILL.md b/design-review/SKILL.md
index c8ce6d3cf..984c4b69b 100644
--- a/design-review/SKILL.md
+++ b/design-review/SKILL.md
@@ -354,6 +354,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/devex-review/SKILL.md b/devex-review/SKILL.md
index 4b38c42b4..f1b393525 100644
--- a/devex-review/SKILL.md
+++ b/devex-review/SKILL.md
@@ -356,6 +356,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/ios-qa/SKILL.md b/ios-qa/SKILL.md
index f9dbc02e6..ab2396d2a 100644
--- a/ios-qa/SKILL.md
+++ b/ios-qa/SKILL.md
@@ -360,6 +360,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/land-and-deploy/SKILL.md b/land-and-deploy/SKILL.md
index b711edc55..fba92d47a 100644
--- a/land-and-deploy/SKILL.md
+++ b/land-and-deploy/SKILL.md
@@ -349,6 +349,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/office-hours/SKILL.md b/office-hours/SKILL.md
index da399d961..8908a9e15 100644
--- a/office-hours/SKILL.md
+++ b/office-hours/SKILL.md
@@ -387,6 +387,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/plan-ceo-review/SKILL.md b/plan-ceo-review/SKILL.md
index db7c12fa3..df5b31466 100644
--- a/plan-ceo-review/SKILL.md
+++ b/plan-ceo-review/SKILL.md
@@ -379,6 +379,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/plan-design-review/SKILL.md b/plan-design-review/SKILL.md
index 921d6e5a6..4a6c85de8 100644
--- a/plan-design-review/SKILL.md
+++ b/plan-design-review/SKILL.md
@@ -352,6 +352,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/plan-devex-review/SKILL.md b/plan-devex-review/SKILL.md
index 5626c73e4..fa96b9fe0 100644
--- a/plan-devex-review/SKILL.md
+++ b/plan-devex-review/SKILL.md
@@ -357,6 +357,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/plan-eng-review/SKILL.md b/plan-eng-review/SKILL.md
index edaba0484..9a8edf91c 100644
--- a/plan-eng-review/SKILL.md
+++ b/plan-eng-review/SKILL.md
@@ -355,6 +355,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/qa-only/SKILL.md b/qa-only/SKILL.md
index 9de1cca6d..1c358cc7b 100644
--- a/qa-only/SKILL.md
+++ b/qa-only/SKILL.md
@@ -352,6 +352,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/qa/SKILL.md b/qa/SKILL.md
index aa5a60782..8002dca92 100644
--- a/qa/SKILL.md
+++ b/qa/SKILL.md
@@ -358,6 +358,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/review/SKILL.md b/review/SKILL.md
index 379719325..2e683de70 100644
--- a/review/SKILL.md
+++ b/review/SKILL.md
@@ -354,6 +354,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/scripts/resolvers/preamble/generate-search-before-building.ts b/scripts/resolvers/preamble/generate-search-before-building.ts
index e1820c2d0..dc41a9b9a 100644
--- a/scripts/resolvers/preamble/generate-search-before-building.ts
+++ b/scripts/resolvers/preamble/generate-search-before-building.ts
@@ -6,6 +6,16 @@ export function generateSearchBeforeBuildingSection(ctx: TemplateContext): strin
 Before building anything unfamiliar, **search first.** See \`${ctx.paths.skillRoot}/ETHOS.md\`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, \`<input type="date">\` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 \`\`\`bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/ship/SKILL.md b/ship/SKILL.md
index 04e5fe98e..4ffbe0af9 100644
--- a/ship/SKILL.md
+++ b/ship/SKILL.md
@@ -354,6 +354,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true
diff --git a/spec/SKILL.md b/spec/SKILL.md
index bca9b39f4..e39a98a4a 100644
--- a/spec/SKILL.md
+++ b/spec/SKILL.md
@@ -352,6 +352,16 @@ Always flag anything that looks wrong — one sentence, what you noticed and its
 Before building anything unfamiliar, **search first.** See `~/.claude/skills/gstack/ETHOS.md`.
 - **Layer 1** (tried and true) — don't reinvent. **Layer 2** (new and popular) — scrutinize. **Layer 3** (first principles) — prize above all.
 
+**The reuse ladder — before writing new code, stop at the first rung that holds:**
+1. A helper, util, or pattern already in this repo — re-implementing what's a few files over is the most common slop.
+2. The standard library.
+3. A native platform feature (CSS over JS, DB constraint over app code, `<input type="date">` over a picker lib).
+4. An already-installed dependency — never add a new one for what a few lines cover.
+
+Then build the complete version of what remains.
+
+**Bug fixes hit root cause, not symptom:** one guard in the shared function beats a guard in every caller — grep the callers, fix it once where they all route through.
+
 **Eureka:** When first-principles reasoning contradicts conventional wisdom, name it and log:
 ```bash
 jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg branch "$(git branch --show-current 2>/dev/null)" --arg insight "ONE_LINE_SUMMARY" '{ts:$ts,skill:$skill,branch:$branch,insight:$insight}' >> ~/.gstack/analytics/eureka.jsonl 2>/dev/null || true