diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 999243e..9b09c4a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,8 +14,8 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v7
-      - uses: actions/setup-node@v7
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
         with:
           node-version: 24
       - run: npm ci
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 0910384..e3b7890 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -10,6 +10,9 @@ on:
   schedule:
     - cron: "17 3 * * 1"
 
+# The analyze job widens its own permissions; everything else gets none.
+permissions: read-all
+
 jobs:
   analyze:
     name: Analyze
@@ -20,12 +23,12 @@ jobs:
       security-events: write
 
     steps:
-      - uses: actions/checkout@v7
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
-      - uses: github/codeql-action/init@v3
+      - uses: github/codeql-action/init@42947a340483f03ba47bb1a039b2c519aab3df85 # v3.37.8
         with:
           languages: javascript-typescript
 
-      - uses: github/codeql-action/analyze@v3
+      - uses: github/codeql-action/analyze@42947a340483f03ba47bb1a039b2c519aab3df85 # v3.37.8
         with:
           category: "/language:javascript-typescript"
diff --git a/.github/workflows/dependency-review.yml b/.github/workflows/dependency-review.yml
index 460031c..b040b64 100644
--- a/.github/workflows/dependency-review.yml
+++ b/.github/workflows/dependency-review.yml
@@ -13,5 +13,5 @@ jobs:
   dependency-review:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v7
-      - uses: actions/dependency-review-action@v4
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/dependency-review-action@2031cfc080254a8a887f58cffee85186f0e49e48 # v4.9.0
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index fe9b716..c13fde5 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -35,15 +35,16 @@ jobs:
     outputs:
       channel: ${{ steps.channel.outputs.channel }}
     steps:
-      - uses: actions/checkout@v7
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       # No registry-url here: it writes an .npmrc auth-token line with a
       # placeholder value, and npm then authenticates with that instead of
       # falling through to OIDC trusted publishing.
-      - uses: actions/setup-node@v7
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
         with:
           node-version: 24
-      # Trusted publishing needs npm 11.5.1 or newer.
-      - run: npm install -g npm@latest
+      # Trusted publishing needs npm 11.5.1 or newer, pinned exactly so a
+      # release never runs an npm nobody reviewed.
+      - run: npm install -g npm@12.0.2
       - run: npm ci
       - run: npm test
       - name: pick channel and version
@@ -103,7 +104,7 @@ jobs:
     if: needs.publish.outputs.channel == 'latest'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/setup-node@v7
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
         with:
           node-version: 24
       # Same invocation the install-loop experiment proved out, telemetry left
diff --git a/.github/workflows/scorecard.yml b/.github/workflows/scorecard.yml
index 8d5acfa..5e3500a 100644
--- a/.github/workflows/scorecard.yml
+++ b/.github/workflows/scorecard.yml
@@ -22,7 +22,7 @@ jobs:
       actions: read
 
     steps:
-      - uses: actions/checkout@v7
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           persist-credentials: false
 
@@ -32,12 +32,12 @@ jobs:
           results_format: sarif
           publish_results: true
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: SARIF file
           path: results.sarif
           retention-days: 5
 
-      - uses: github/codeql-action/upload-sarif@v3
+      - uses: github/codeql-action/upload-sarif@42947a340483f03ba47bb1a039b2c519aab3df85 # v3.37.8
         with:
           sarif_file: results.sarif
diff --git a/SECURITY.md b/SECURITY.md
new file mode 100644
index 0000000..65258f5
--- /dev/null
+++ b/SECURITY.md
@@ -0,0 +1,24 @@
+# Security
+
+## Reporting a vulnerability
+
+Report vulnerabilities privately through GitHub: [Security > Report a
+vulnerability](https://github.com/only-cli/oc/security/advisories/new).
+Please do not open a public issue for anything exploitable.
+
+Expect an acknowledgement within a week. Fixes ship as a patch release,
+and the advisory is published once the fix is out.
+
+## Scope
+
+oc fetches untrusted web pages by design, so the interesting bugs are the
+ones where page content escapes its role as data: rendered text that can
+alter what an agent executes, URLs that reach private or internal hosts
+despite the SSRF guard, or a crafted page that breaks the distiller. Bugs
+in the experiments/ directory are out of scope; nothing there ships in
+the package.
+
+## Supported versions
+
+Only the latest release on npm is supported. There is no backporting; a
+security fix means a new release.
diff --git a/experiments/skills-install-remove-loop/Dockerfile b/experiments/skills-install-remove-loop/Dockerfile
index 4c6ce48..b559398 100644
--- a/experiments/skills-install-remove-loop/Dockerfile
+++ b/experiments/skills-install-remove-loop/Dockerfile
@@ -1,4 +1,4 @@
-FROM node:24-bookworm-slim
+FROM node:24-bookworm-slim@sha256:3638d9a6fe4030bd716be989438248074489337ba3275657f93595428be4fc03
 
 RUN apt-get update \
     && apt-get install --yes --no-install-recommends ca-certificates git \