diff --git a/.github/workflows/agent-decompose.yml b/.github/workflows/agent-decompose.yml
index 9833b81156..fb238ff204 100644
--- a/.github/workflows/agent-decompose.yml
+++ b/.github/workflows/agent-decompose.yml
@@ -51,7 +51,7 @@ jobs:
       - name: Setup Zig
         uses: goto-bus-stop/setup-zig@v2
         with:
-          version: 0.15.0-dev
+          version: 0.15.2-dev
 
       - name: Build tri CLI
         run: zig build
diff --git a/.github/workflows/build-compiler-release.yml b/.github/workflows/build-compiler-release.yml
index cadf7fb58a..1718083447 100644
--- a/.github/workflows/build-compiler-release.yml
+++ b/.github/workflows/build-compiler-release.yml
@@ -13,7 +13,7 @@ on:
   workflow_dispatch:
 
 env:
-  ZIG_VERSION: '0.13.0'
+  ZIG_VERSION: '0.15.2'
 
 jobs:
   build-linux:
diff --git a/.github/workflows/docs-check.yml b/.github/workflows/docs-check.yml
index 731b7551ea..8d8f72b17c 100644
--- a/.github/workflows/docs-check.yml
+++ b/.github/workflows/docs-check.yml
@@ -101,7 +101,7 @@ jobs:
       - name: Install Zig
         uses: goto-bus-stop/setup-zig@v2
         with:
-          version: 0.15.0
+          version: 0.15.2
 
       - name: Build tri CLI
         run: |
diff --git a/.github/workflows/extension-release.yml b/.github/workflows/extension-release.yml
index 678303ab4c..aadb8d920a 100644
--- a/.github/workflows/extension-release.yml
+++ b/.github/workflows/extension-release.yml
@@ -40,7 +40,7 @@ jobs:
       - name: Setup Zig
         uses: goto-bus-stop/setup-zig@v2
         with:
-          version: 0.13.0
+          version: 0.15.2
       
       - name: Setup Node.js
         uses: actions/setup-node@v4
diff --git a/.github/workflows/extension-tests.yml b/.github/workflows/extension-tests.yml
index fa245a0714..18cbbc8f14 100644
--- a/.github/workflows/extension-tests.yml
+++ b/.github/workflows/extension-tests.yml
@@ -27,7 +27,7 @@ jobs:
       - name: Setup Zig
         uses: goto-bus-stop/setup-zig@v2
         with:
-          version: 0.13.0
+          version: 0.15.2
       
       - name: Build WASM
         run: |
diff --git a/.github/workflows/nexus-build.yml b/.github/workflows/nexus-build.yml
index 5abb944609..2a793abe32 100644
--- a/.github/workflows/nexus-build.yml
+++ b/.github/workflows/nexus-build.yml
@@ -23,7 +23,7 @@ jobs:
       - name: Setup Zig
         uses: goto-bus-stop/setup-zig@v2
         with:
-          version: 0.15.0
+          version: 0.15.2
 
       - name: Build ${{ matrix.module }}
         working-directory: trinity-nexus
@@ -42,7 +42,7 @@ jobs:
       - name: Setup Zig
         uses: goto-bus-stop/setup-zig@v2
         with:
-          version: 0.15.0
+          version: 0.15.2
 
       - name: Build all modules
         working-directory: trinity-nexus
diff --git a/.github/workflows/record-demos.yml b/.github/workflows/record-demos.yml
index 6872a5d11b..fccbcbd421 100644
--- a/.github/workflows/record-demos.yml
+++ b/.github/workflows/record-demos.yml
@@ -18,7 +18,7 @@ jobs:
       - name: Install Zig
         uses: goto-bus/setup-zig@v2
         with:
-          version: 0.15.0
+          version: 0.15.2
 
       - name: Install VHS
         run: |
diff --git a/CLAUDE.md b/CLAUDE.md
index 99beb5af34..0d2e4084ad 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -1,5 +1,22 @@
 # CLAUDE.md
 
+## Pinned Zig version — 0.15.2
+
+**Every workflow uses `0.15.2`.** Before 2026-08-10 they did not: 22 places said 0.15.2,
+five said 0.15.0, and three that actually run `zig build` — `build-compiler-release.yml`,
+`extension-tests.yml`, `extension-release.yml` — said 0.13.0, two majors behind.
+
+This document previously carried migration rules for 0.14 and 0.15 at once, which is how a
+reader ends up applying the wrong one.
+
+**A locally installed Zig is not the CI toolchain.** On 0.16 a clean checkout of `main`
+fails at `build.zig:67` with `no field or member function named 'linkLibC'` — an error CI
+never sees, because `linkLibC` still exists in 0.15. A green local build proves nothing
+about CI, and a red one says nothing about your change. Match 0.15.2 locally before drawing
+any conclusion from a build.
+
+---
+
 ## Zig 0.15 API Compatibility and Migration Rules
 
 **Reference**: docs/zig-migration-rules.md — https://ziglang.org/download/0.15.1/