diff --git a/.claude/hooks/session-start.sh b/.claude/hooks/session-start.sh
new file mode 100755
index 000000000..59319b0c9
--- /dev/null
+++ b/.claude/hooks/session-start.sh
@@ -0,0 +1,23 @@
+#!/bin/bash
+# SessionStart hook: install dependencies so tests and linters work in
+# Claude Code on the web sessions. Idempotent and non-interactive.
+set -euo pipefail
+
+# Only run in the remote (Claude Code on the web) environment; local sessions
+# manage their own virtualenv.
+if [ "${CLAUDE_CODE_REMOTE:-}" != "true" ]; then
+  exit 0
+fi
+
+cd "$CLAUDE_PROJECT_DIR"
+
+# Install uv if it isn't already on PATH (the remote image may not ship it).
+if ! command -v uv >/dev/null 2>&1; then
+  curl -LsSf https://astral.sh/uv/install.sh | sh
+  export PATH="$HOME/.local/bin:$PATH"
+  echo 'export PATH="$HOME/.local/bin:$PATH"' >> "$CLAUDE_ENV_FILE"
+fi
+
+# --frozen installs straight from the committed uv.lock without re-resolving or
+# rewriting it (mirrors CI). --all-extras pulls in the dev tools (pytest, ruff).
+uv sync --all-extras --frozen
diff --git a/.claude/settings.json b/.claude/settings.json
new file mode 100644
index 000000000..e06b0338e
--- /dev/null
+++ b/.claude/settings.json
@@ -0,0 +1,14 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "$CLAUDE_PROJECT_DIR/.claude/hooks/session-start.sh"
+          }
+        ]
+      }
+    ]
+  }
+}
diff --git a/.gitignore b/.gitignore
index 0a6775b2a..73267c09a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,6 +17,13 @@ graphify-out/
 .graphify_*.json
 .graphify_python
 .claude/
+# Track the shared SessionStart hook and its settings (activates the repo for
+# Claude Code on the web); keep all other local .claude/ state ignored.
+!.claude/
+.claude/*
+!.claude/hooks/
+!.claude/hooks/session-start.sh
+!.claude/settings.json
 skills/
 # The packaged skill bundles under graphify/skills/ are generated, committed
 # artifacts (rendered by tools/skillgen). Keep them tracked even though the