diff --git a/.changeset/cap-controller-resources.md b/.changeset/cap-controller-resources.md
new file mode 100644
index 00000000..d313529e
--- /dev/null
+++ b/.changeset/cap-controller-resources.md
@@ -0,0 +1,13 @@
+---
+"@prover-coder-ai/docker-git": patch
+---
+
+feat: cap controller container CPU, memory, and PID consumption
+
+Adds default `cpus`, `mem_limit`, `memswap_limit`, and `pids_limit` to the
+`docker-git-api` controller in `docker-compose.yml` and
+`docker-compose.api.yml`. Each value is parameterized so operators can
+override it via `DOCKER_GIT_CONTROLLER_CPUS`, `DOCKER_GIT_CONTROLLER_MEMORY`,
+and `DOCKER_GIT_CONTROLLER_PIDS`. Defaults: 2 CPUs, 4 GiB RAM/swap, 4096 PIDs.
+This complements the existing per-project caps so a runaway controller
+cannot consume the entire host.
diff --git a/README.md b/README.md
index 44c37fe3..a8d2d7cd 100644
--- a/README.md
+++ b/README.md
@@ -113,3 +113,21 @@ When the CLI cannot acquire Docker access it now prints a message that
 names the specific failure mode, restates the host-Docker contract, and
 lists remediation steps for that exact mode. Implementation lives in
 `packages/app/src/docker-git/controller-docker-diagnostics.ts`.
+
+## Resource limits
+
+`docker-git` caps host resource consumption at two layers so a runaway
+project (or the controller itself) cannot consume the entire system.
+
+- **Per-project containers** ship with a default limit of `30%` CPU and
+  `30%` RAM (resolved against the host on `apply`). Override via
+  `--cpu` / `--ram` (or per-project `docker-git.json`).
+- **Controller container** (`docker-git-api`) is capped in
+  `docker-compose.yml` and `docker-compose.api.yml`. Override via
+  environment variables before `./ctl up`:
+
+  | Variable                       | Default | Purpose                              |
+  | ------------------------------ | ------- | ------------------------------------ |
+  | `DOCKER_GIT_CONTROLLER_CPUS`   | `2.0`   | Maximum CPU cores for the controller |
+  | `DOCKER_GIT_CONTROLLER_MEMORY` | `4g`    | Memory + swap cap (matched values)   |
+  | `DOCKER_GIT_CONTROLLER_PIDS`   | `4096`  | Maximum PIDs inside the controller   |
diff --git a/docker-compose.api.yml b/docker-compose.api.yml
index bee3eb1b..f2031bb8 100644
--- a/docker-compose.api.yml
+++ b/docker-compose.api.yml
@@ -37,6 +37,10 @@ services:
     cgroup: host
     init: true
     restart: unless-stopped
+    cpus: ${DOCKER_GIT_CONTROLLER_CPUS:-2.0}
+    mem_limit: ${DOCKER_GIT_CONTROLLER_MEMORY:-4g}
+    memswap_limit: ${DOCKER_GIT_CONTROLLER_MEMORY:-4g}
+    pids_limit: ${DOCKER_GIT_CONTROLLER_PIDS:-4096}
 
 volumes:
   docker_git_projects:
diff --git a/docker-compose.yml b/docker-compose.yml
index e955aff2..ae608961 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -39,6 +39,10 @@ services:
     cgroup: host
     init: true
     restart: unless-stopped
+    cpus: ${DOCKER_GIT_CONTROLLER_CPUS:-2.0}
+    mem_limit: ${DOCKER_GIT_CONTROLLER_MEMORY:-4g}
+    memswap_limit: ${DOCKER_GIT_CONTROLLER_MEMORY:-4g}
+    pids_limit: ${DOCKER_GIT_CONTROLLER_PIDS:-4096}
 
 volumes:
   docker_git_projects:
diff --git a/packages/app/tests/docker-git/controller-resource-limits.test.ts b/packages/app/tests/docker-git/controller-resource-limits.test.ts
new file mode 100644
index 00000000..36e01579
--- /dev/null
+++ b/packages/app/tests/docker-git/controller-resource-limits.test.ts
@@ -0,0 +1,42 @@
+import { NodeContext } from "@effect/platform-node"
+import * as FileSystem from "@effect/platform/FileSystem"
+import * as Path from "@effect/platform/Path"
+import { describe, expect, it } from "@effect/vitest"
+import { Effect } from "effect"
+
+const composeFiles: ReadonlyArray<string> = ["docker-compose.yml", "docker-compose.api.yml"]
+
+const readComposeFile = (relativePath: string): Effect.Effect<string> =>
+  Effect.gen(function*(_) {
+    const fs = yield* _(FileSystem.FileSystem)
+    const path = yield* _(Path.Path)
+    return yield* _(fs.readFileString(path.join("..", "..", relativePath)))
+  }).pipe(
+    Effect.provide(NodeContext.layer),
+    Effect.orDie
+  )
+
+describe("controller compose resource limits", () => {
+  for (const composeFile of composeFiles) {
+    describe(composeFile, () => {
+      it.effect("caps controller CPU usage", () =>
+        Effect.gen(function*(_) {
+          const contents = yield* _(readComposeFile(composeFile))
+          expect(contents).toMatch(/cpus: \$\{DOCKER_GIT_CONTROLLER_CPUS:-\d+(?:\.\d+)?\}/u)
+        }))
+
+      it.effect("caps controller memory and swap together", () =>
+        Effect.gen(function*(_) {
+          const contents = yield* _(readComposeFile(composeFile))
+          expect(contents).toMatch(/mem_limit: \$\{DOCKER_GIT_CONTROLLER_MEMORY:-\d+[a-zA-Z]+\}/u)
+          expect(contents).toMatch(/memswap_limit: \$\{DOCKER_GIT_CONTROLLER_MEMORY:-\d+[a-zA-Z]+\}/u)
+        }))
+
+      it.effect("caps controller PIDs to prevent fork bombs", () =>
+        Effect.gen(function*(_) {
+          const contents = yield* _(readComposeFile(composeFile))
+          expect(contents).toMatch(/pids_limit: \$\{DOCKER_GIT_CONTROLLER_PIDS:-\d+\}/u)
+        }))
+    })
+  }
+})