diff --git a/lexicons/README.md b/lexicons/README.md
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+# Vendored Lexicons
+
+This directory contains vendored copies of AT Protocol lexicon definitions for the Tangled.org service.
+
+## Source
+
+These lexicons are downloaded from the tangled.org core repository:
+- **Source**: `https://tangled.org/tangled.org/core/raw/master/lexicons/`
+- **Repository**: `https://tangled.org/tangled.org/core`
+- **Last Updated**: 2026-02-09
+
+## Structure
+
+- `sh/tangled/` - Tangled-specific lexicons
+  - `issue/` - Issue record types
+  - `pulls/` - Pull request record types
+  - `repo/` - Repository record types
+  - `label/` - Label/tag record types
+  - `pipeline/` - CI/CD pipeline types
+  - `actor/`, `feed/`, `graph/`, `git/`, `knot/`, `spindle/`, `string/` - Other types
+
+## Updating Lexicons
+
+When Tangled.org updates their lexicon schemas, run the update script:
+
+```bash
+npm run update-lexicons
+```
+
+This script:
+1. Downloads the latest lexicon files from tangled.org over HTTPS
+2. Saves them to the `lexicons/` directory
+3. Preserves the directory structure
+
+After updating lexicons:
+1. Update the "Last Updated" date in this README
+2. Regenerate client code: `npm run codegen`
+3. Run tests to ensure compatibility: `npm test`
+4. Commit both lexicon updates and generated code changes
+
+**Manual Update** (if script fails):
+- Lexicons can be manually downloaded from: `https://tangled.org/tangled.org/core/raw/master/lexicons/<path>`
+- Example: `https://tangled.org/tangled.org/core/raw/master/lexicons/issue/issue.json`
+
+## Code Generation
+
+Client TypeScript code is generated from these lexicons using `@atproto/lex-cli`:
+
+```bash
+npm run codegen
+```
+
+This generates type-safe client code in `src/lexicon/` which is committed to version control.
diff --git a/scripts/update-lexicons.sh b/scripts/update-lexicons.sh
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+#!/usr/bin/env bash
+set -euo pipefail
+
+# Base URL for tangled.org core repository
+BASE_URL="https://tangled.org/tangled.org/core/raw/master/lexicons"
+
+# Create lexicons directory
+mkdir -p lexicons/sh/tangled
+
+# Function to download a lexicon file
+download_lexicon() {
+  local path="$1"
+  local dest="lexicons/sh/tangled/$path"
+  local url="$BASE_URL/$path"
+
+  echo "Downloading $path..."
+  mkdir -p "$(dirname "$dest")"
+  curl -fsSL "$url" -o "$dest"
+}
+
+# Download all Tangled lexicons
+echo "Fetching latest lexicons from tangled.org..."
+
+# Issue lexicons
+download_lexicon "issue/issue.json"
+download_lexicon "issue/comment.json"
+download_lexicon "issue/state.json"
+download_lexicon "issue/open.json"
+download_lexicon "issue/closed.json"
+
+# Pull request lexicons
+download_lexicon "pulls/pull.json"
+download_lexicon "pulls/comment.json"
+download_lexicon "pulls/state.json"
+download_lexicon "pulls/open.json"
+download_lexicon "pulls/closed.json"
+download_lexicon "pulls/merged.json"
+
+# Repository lexicons
+download_lexicon "repo/repo.json"
+download_lexicon "repo/create.json"
+download_lexicon "repo/delete.json"
+download_lexicon "repo/archive.json"
+download_lexicon "repo/collaborator.json"
+download_lexicon "repo/blob.json"
+download_lexicon "repo/tree.json"
+download_lexicon "repo/log.json"
+download_lexicon "repo/diff.json"
+download_lexicon "repo/branch.json"
+download_lexicon "repo/branches.json"
+download_lexicon "repo/defaultBranch.json"
+download_lexicon "repo/getDefaultBranch.json"
+download_lexicon "repo/deleteBranch.json"
+download_lexicon "repo/tag.json"
+download_lexicon "repo/tags.json"
+download_lexicon "repo/compare.json"
+download_lexicon "repo/merge.json"
+download_lexicon "repo/mergeCheck.json"
+download_lexicon "repo/forkStatus.json"
+download_lexicon "repo/forkSync.json"
+download_lexicon "repo/artifact.json"
+download_lexicon "repo/hiddenRef.json"
+download_lexicon "repo/languages.json"
+download_lexicon "repo/addSecret.json"
+download_lexicon "repo/listSecrets.json"
+download_lexicon "repo/removeSecret.json"
+
+# Label lexicons
+download_lexicon "label/definition.json"
+download_lexicon "label/op.json"
+
+# Pipeline lexicons
+download_lexicon "pipeline/pipeline.json"
+download_lexicon "pipeline/status.json"
+download_lexicon "pipeline/cancelPipeline.json"
+
+# Top-level lexicons
+download_lexicon "owner.json"
+download_lexicon "publicKey.json"
+
+# Actor lexicons
+download_lexicon "actor/profile.json"
+
+# Feed lexicons
+download_lexicon "feed/reaction.json"
+download_lexicon "feed/star.json"
+
+# Graph lexicons
+download_lexicon "graph/follow.json"
+
+# Git lexicons
+download_lexicon "git/refUpdate.json"
+
+# Knot lexicons
+download_lexicon "knot/knot.json"
+download_lexicon "knot/listKeys.json"
+download_lexicon "knot/member.json"
+download_lexicon "knot/version.json"
+
+# Spindle lexicons
+download_lexicon "spindle/spindle.json"
+download_lexicon "spindle/member.json"
+
+# String lexicons
+download_lexicon "string/string.json"
+
+echo ""
+echo "✓ Lexicons downloaded successfully"
+echo "  Run 'npm run codegen' to regenerate TypeScript types"