diff --git a/docs/guides/DOCKER_GUIDE.md b/docs/guides/DOCKER_GUIDE.md
index 5233889912..b1e6968cfc 100644
--- a/docs/guides/DOCKER_GUIDE.md
+++ b/docs/guides/DOCKER_GUIDE.md
@@ -147,11 +147,11 @@ The prod stack runs in parallel with the dev compose (different container names,
 
 The repository ships a multi-stage Dockerfile (`Dockerfile`). Three stages are exposed; pick the right `target` for your use case.
 
-| Stage         | Base image                 | Purpose                                                                                                                                                            |
-| ------------- | -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
-| `builder`     | `node:24.15.0-trixie-slim` | Installs deps (`npm ci --legacy-peer-deps`) and runs `npm run build -- --webpack`                                                                                  |
-| `runner-base` | `node:24.15.0-trixie-slim` | Production runtime with the Next.js standalone output. **No provider CLIs bundled.**                                                                               |
-| `runner-cli`  | `runner-base`              | Adds `git`, `docker.io`, `docker-compose` and global CLIs: `@openai/codex`, `@anthropic-ai/claude-code`, `droid`, `openclaw`. **Pick this for agentic workflows.** |
+| Stage         | Base image            | Purpose                                                                                                                                                            |
+| ------------- | --------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
+| `builder`     | `node:26-trixie-slim` | Installs deps (`npm ci --legacy-peer-deps`) and runs `npm run build` (Turbopack by default — see Build-time resources below)                                       |
+| `runner-base` | `node:26-trixie-slim` | Production runtime with the Next.js standalone output. **No provider CLIs bundled.**                                                                               |
+| `runner-cli`  | `runner-base`         | Adds `git`, `docker.io`, `docker-compose` and global CLIs: `@openai/codex`, `@anthropic-ai/claude-code`, `droid`, `openclaw`. **Pick this for agentic workflows.** |
 
 Build a specific target manually:
 
@@ -160,6 +160,42 @@ docker build --target runner-base -t omniroute:base .
 docker build --target runner-cli  -t omniroute:cli  .
 ```
 
+### Build-time resources
+
+Two build args control what the `builder` stage costs. They are build-time only —
+`OMNIROUTE_MEMORY_MB` (below) is a separate, runtime knob.
+
+| Build arg                   | Default | Effect                                                                 |
+| --------------------------- | ------- | ---------------------------------------------------------------------- |
+| `OMNIROUTE_USE_TURBOPACK`   | `1`     | `0` builds with webpack instead. Lower peak memory, slower.            |
+| `OMNIROUTE_BUILD_MEMORY_MB` | `4096`  | V8 heap ceiling (`--max-old-space-size`) for the spawned `next build`. |
+
+Turbopack compiles in native Rust memory that lives **outside** the V8 heap, so
+`OMNIROUTE_BUILD_MEMORY_MB` does not bound it. On a host with a memory ceiling the
+build is then SIGKILLed by the OOM killer with no error text at all — it simply
+stops mid-`Creating an optimized production build`, which reads like a hang rather
+than an out-of-memory. If the build host is constrained, switch bundlers:
+
+```bash
+docker build --target runner-base \
+  --build-arg OMNIROUTE_USE_TURBOPACK=0 \
+  -t omniroute:base .
+```
+
+`webpackBuildWorker` is enabled, so `next build` runs a parent **and** a worker
+process and each honours `OMNIROUTE_BUILD_MEMORY_MB` separately. Size the container
+ceiling above roughly twice that value, not once.
+
+Measured on this tree (`--target runner-base`, `OMNIROUTE_BUILD_MEMORY_MB=6144`):
+
+| Bundler   | Container ceiling | Result                        |
+| --------- | ----------------- | ----------------------------- |
+| Turbopack | 8 GiB / 16 GiB    | OOM-killed at both, silently  |
+| webpack   | 8 GiB             | build worker SIGKILLed        |
+| webpack   | 12 GiB            | succeeded, peaked at 11.1 GiB |
+
+### Runtime defaults
+
 Defaults exported by `runner-base`: `PORT=20128`, `HOSTNAME=0.0.0.0`, `NODE_OPTIONS=--max-old-space-size=512`, `DATA_DIR=/app/data`, `OMNIROUTE_MIGRATIONS_DIR=/app/migrations`.
 
 Memory behavior in Docker: