diff --git a/.github/workflows/supply-chain-audit.yml b/.github/workflows/supply-chain-audit.yml
index 417e7b21f84..69a9a115c87 100644
--- a/.github/workflows/supply-chain-audit.yml
+++ b/.github/workflows/supply-chain-audit.yml
@@ -11,6 +11,7 @@ on:
       - '**/sitecustomize.py'
       - '**/usercustomize.py'
       - '**/__init__.pth'
+      - 'pyproject.toml'
 
 permissions:
   pull-requests: write
@@ -137,3 +138,68 @@ jobs:
         run: |
           echo "::error::CRITICAL supply chain risk patterns detected in this PR. See the PR comment for details."
           exit 1
+
+  dep-bounds:
+    name: Check PyPI dependency upper bounds
+    runs-on: ubuntu-latest
+    if: contains(github.event.pull_request.changed_files_url, 'pyproject.toml') || true
+    steps:
+      - name: Checkout
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5  # v4
+        with:
+          fetch-depth: 0
+
+      - name: Check for unbounded PyPI deps
+        id: bounds
+        run: |
+          set -euo pipefail
+
+          BASE="${{ github.event.pull_request.base.sha }}"
+          HEAD="${{ github.event.pull_request.head.sha }}"
+
+          # Only check added lines in pyproject.toml
+          ADDED=$(git diff "$BASE".."$HEAD" -- pyproject.toml | grep '^+' | grep -v '^+++' || true)
+
+          if [ -z "$ADDED" ]; then
+            echo "found=false" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          # Match PyPI dep specs that have >= but no < ceiling.
+          # Pattern: "package>=version" without a following ",<" bound.
+          # Excludes git+ URLs (which use commit SHAs) and comments.
+          UNBOUNDED=$(echo "$ADDED" | grep -oE '"[a-zA-Z0-9_-]+(\[[^\]]*\])?>=[ 0-9.]+"' | grep -v ',<' || true)
+
+          if [ -n "$UNBOUNDED" ]; then
+            echo "found=true" >> "$GITHUB_OUTPUT"
+            echo "$UNBOUNDED" > /tmp/unbounded.txt
+          else
+            echo "found=false" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Post unbounded dep warning
+        if: steps.bounds.outputs.found == 'true'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          BODY="## ⚠️ Unbounded PyPI Dependency Detected
+
+          This PR adds PyPI dependencies without a \`<next_major\` upper bound. Per our [supply chain policy](../blob/main/CONTRIBUTING.md#dependency-pinning-policy-supply-chain-hardening), all PyPI deps must be pinned as \`>=floor,<next_major\`.
+
+          **Unbounded specs found:**
+          \`\`\`
+          $(cat /tmp/unbounded.txt)
+          \`\`\`
+
+          **Fix:** Add an upper bound, e.g. \`\"package>=1.2.0,<2\"\`
+
+          ---
+          *See PR #2810 and CONTRIBUTING.md for the full policy rationale.*"
+
+          gh pr comment "${{ github.event.pull_request.number }}" --body "$BODY" || echo "::warning::Could not post PR comment (expected for fork PRs)"
+
+      - name: Fail on unbounded deps
+        if: steps.bounds.outputs.found == 'true'
+        run: |
+          echo "::error::PyPI dependencies without upper bounds detected. Add <next_major ceiling per CONTRIBUTING.md policy."
+          exit 1
diff --git a/AGENTS.md b/AGENTS.md
index d5d32f99c3d..7c324f50332 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -308,6 +308,29 @@ The registry handles schema collection, dispatch, availability checking, and err
 
 ---
 
+## Dependency Pinning Policy
+
+All dependencies must have upper bounds to limit supply-chain attack surface.
+This policy was established after the litellm compromise (PR #2796, #2810) and
+reinforced after the Mini Shai-Hulud worm campaign (May 2026).
+
+| Source type | Treatment | Example |
+|---|---|---|
+| PyPI package | `>=floor,<next_major` | `"httpx>=0.28.1,<1"` |
+| Git URL | Commit SHA | `git+https://...@<40-char-sha>` |
+| GitHub Actions | Commit SHA + comment | `uses: actions/checkout@<sha>  # v4` |
+| CI-only pip | `==exact` | `pyyaml==6.0.2` |
+
+**When adding a new dependency to `pyproject.toml`:**
+1. Pin to `>=current_version,<next_major` for post-1.0 (e.g. `>=1.5.0,<2`).
+2. For pre-1.0 packages, use `<0.(current_minor + 2)` (e.g. `>=0.29,<0.32`).
+3. Never commit a bare `>=X.Y.Z` without a ceiling — CI and reviewers will reject it.
+4. Run `uv lock` to regenerate `uv.lock` with hashes.
+
+Reference: #2810 (bounds pass), #9801 (SHA pinning + audit CI).
+
+---
+
 ## Adding Configuration
 
 ### config.yaml options:
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 9cbc26112f6..36b1e9df2d5 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -800,6 +800,47 @@ Hermes has terminal access. Security matters.
 
 If your PR affects security, note it explicitly in the description.
 
+### Dependency pinning policy (supply chain hardening)
+
+After the [litellm supply chain compromise](https://github.com/BerriAI/litellm/issues/24512) in March 2026 and the [Mini Shai-Hulud worm campaign](https://socket.dev/blog/tanstack-npm-packages-compromised-mini-shai-hulud-supply-chain-attack) in May 2026, all dependencies must follow these rules:
+
+| Source type | Required treatment | Rationale |
+|---|---|---|
+| **PyPI package** | `>=floor,<next_major` | PyPI versions are immutable once published, but new versions can be pushed into your range. A `<next_major` ceiling stops a 1.x install from upgrading to a malicious 2.0.0. |
+| **Git URL** (atroposlib, tinker, yc-bench, Baileys) | Full commit SHA | Branches and tags are mutable refs; SHA is content-addressed. |
+| **GitHub Actions** | Full commit SHA + version comment | Action tags are mutable refs (e.g. tj-actions/changed-files March 2025). Pin as `uses: owner/action@<sha>  # vX.Y.Z` |
+| **CI-only pip installs** | `==exact` | Hermetic CI builds; churn is acceptable. |
+
+**Every new PyPI dependency in a PR must have a `<next_major` upper bound.** PRs adding unbounded `>=X.Y.Z` specs will be rejected by reviewers. The `supply-chain-audit.yml` CI workflow also flags dependency manifest changes for manual review.
+
+**How to determine the ceiling:**
+- If the package is at version `1.x.y`, use `<2`.
+- If the package is at version `0.x.y` (pre-1.0), use `<0.(current_minor + 2)` — e.g. if current is `0.29.x`, use `<0.32`. This gives ~2 minor versions of headroom while keeping the window small enough that a hostile takeover version is unlikely to land inside it.
+- Exception: packages with very stable APIs (e.g. `aiohttp-socks`) can use `<1` at reviewer discretion.
+
+**Examples:**
+```toml
+# ✅ Correct — post-1.0
+"openai>=2.21.0,<3"
+"pydantic>=2.12.5,<3"
+
+# ✅ Correct — pre-1.0 (tight minor window)
+"asyncpg>=0.29,<0.32"
+"aiosqlite>=0.20,<0.23"
+"hindsight-client>=0.4.22,<0.5"
+
+# ❌ Rejected — no upper bound
+"some-package>=1.2.3"
+
+# ❌ Rejected — too tight (blocks legitimate patches)
+"some-package==1.2.3"
+
+# ❌ Rejected — too loose for pre-1.0 (allows 80 minor versions)
+"some-package>=0.20,<1"
+```
+
+**Reference PRs:** #2796 (litellm removal), #2810 (upper bounds pass), #9801 (SHA pinning + supply-chain-audit CI).
+
 ---
 
 ## Pull Request Process