diff --git a/.github/workflows/compat.yml b/.github/workflows/compat.yml
index f1e529f..9dfbcc1 100644
--- a/.github/workflows/compat.yml
+++ b/.github/workflows/compat.yml
@@ -39,7 +39,7 @@ jobs:
       - uses: actions/checkout@v7
       - uses: oven-sh/setup-bun@v2
         with:
-          bun-version: 1.3.6
+          bun-version: 1.4.0
 
       - name: Cache Bun dependencies
         uses: actions/cache@v6
diff --git a/.github/workflows/maintenance.yml b/.github/workflows/maintenance.yml
index 497ad0b..f19fd7c 100644
--- a/.github/workflows/maintenance.yml
+++ b/.github/workflows/maintenance.yml
@@ -19,7 +19,7 @@ permissions:
   issues: write
 
 env:
-  BUN_PIN: "1.3.6" # must match test.yml / compat.yml
+  BUN_PIN: "1.4.0" # must match test.yml / compat.yml
   REDIS_PIN: "7.4.0-v8" # must match test.yml / compat.yml / docker-compose.yml
 
 jobs:
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 656024b..b115c67 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -15,7 +15,7 @@ jobs:
       - uses: actions/checkout@v7
       - uses: oven-sh/setup-bun@v2
         with:
-          bun-version: 1.3.6
+          bun-version: 1.4.0
 
       - name: Cache Bun dependencies
         uses: actions/cache@v6
@@ -57,7 +57,7 @@ jobs:
       - uses: actions/checkout@v7
       - uses: oven-sh/setup-bun@v2
         with:
-          bun-version: 1.3.6
+          bun-version: 1.4.0
 
       - name: Cache Bun dependencies
         uses: actions/cache@v6
diff --git a/CLAUDE.md b/CLAUDE.md
index 57c6000..591e3e9 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -13,7 +13,7 @@ Sibling project to [up-redis](https://github.com/Coriou/up-redis) (same idea, bu
 - **Validation:** Zod v4
 - **Linting/Format:** Biome v2
 - **Testing:** `bun test` (built-in, Jest-compatible)
-- **Container:** Docker (oven/bun:1.3-alpine) + Redis Stack (pinned `7.4.0-v8`)
+- **Container:** Docker (oven/bun:1.4-alpine) + Redis Stack (pinned `7.4.0-v8`)
 
 **Not a Next.js/Vercel project.** Pure backend service.
 
diff --git a/docs/RUNBOOK.md b/docs/RUNBOOK.md
index 893d186..c7f7c94 100644
--- a/docs/RUNBOOK.md
+++ b/docs/RUNBOOK.md
@@ -25,7 +25,7 @@ Verified baseline at runbook creation (2026-08-22): **383 tests** — 249 unit /
 
 | Mechanism | When | Watches | Failure signal |
 |---|---|---|---|
-| `test.yml` | push / PR touching code | our code vs pinned Bun 1.3.6 + Redis Stack `7.4.0-v8` | red CI on the PR |
+| `test.yml` | push / PR touching code | our code vs pinned Bun 1.4.0 + Redis Stack `7.4.0-v8` | red CI on the PR |
 | `compat.yml` | Mon 09:00 UTC | `@upstash/vector@latest` against us | issue labeled `sdk-compat` |
 | `maintenance.yml` | Mon 09:30 UTC | npm advisory DB, `bun@latest`, `redis-stack-server:latest`, Docker artifact | issues labeled `security` / `maintenance` |
 | `dependabot.yml` | weekly | bun deps, GitHub Actions pins, Dockerfile base image, compose Redis pin | PRs labeled `dependencies` |