diff --git a/CHANGELOG.md b/CHANGELOG.md
index 658d640e..a8e98d8d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,20 @@ PyPI version — not the changelog header.
 
 ## [2026-07-05]
 
+### Fixed
+
+- **Installer no longer destroys a user's custom Claude Code hooks (DPLAN-0234
+  Strand C).** setup.sh used to write `settings["hooks"]` wholesale — anyone
+  with their own hooks in `~/.claude/settings.json` lost them on install or
+  re-run. Now it merges: every AIPass bridge entry (identified by the
+  `bridges/claude.py` marker) is refreshed, while user-wired hooks and custom
+  events are preserved. Verified against fixtures: custom hooks survive, stale
+  AIPass entries are replaced without duplicates, and the fresh-install output
+  is shape-identical to before (7 events, 6 UserPromptSubmit + 6 PreCompact
+  entries). Found while fire-testing a fresh install's hooks in Docker — all
+  17 wired hook entries pass on a cold Linux clone (real kernel/navmap/branch
+  prompt bytes, git gate blocks, clean no-ops on empty state).
+
 ### Added
 
 - **`./aipass` — repo-root cold-clone launcher (DPLAN-0234 Strand B).** The
diff --git a/setup.sh b/setup.sh
index d58a5267..b288bf19 100755
--- a/setup.sh
+++ b/setup.sh
@@ -657,7 +657,7 @@ else:
 # UserPromptSubmit: 5 separate entries (EventType:hook_name) to avoid output merging
 # PreToolUse, PostToolUse, SubagentStop, Stop, Notification: single aggregate entries
 # PreCompact: 3 hooks x 2 matchers (manual + auto) = 6 entries
-settings["hooks"] = {
+aipass_hooks = {
     "UserPromptSubmit": [
         {"hooks": [{"type": "command", "command": f"{bridge} UserPromptSubmit:tier0_kernel"}]},
         {"hooks": [{"type": "command", "command": f"{bridge} UserPromptSubmit:navmap"}]},
@@ -693,6 +693,19 @@ settings["hooks"] = {
     ],
 }
 
+# Merge, don't replace (DPLAN-0234 Strand C): refresh every AIPass bridge entry
+# (identified by the bridges/claude.py marker) but preserve any hooks the user
+# wired themselves. Re-runs stay idempotent; custom hooks survive reinstall.
+existing_hooks = settings.get("hooks", {})
+merged_hooks = {}
+for event in set(existing_hooks) | set(aipass_hooks):
+    user_entries = [
+        entry for entry in existing_hooks.get(event, [])
+        if "bridges/claude.py" not in json.dumps(entry)
+    ]
+    merged_hooks[event] = aipass_hooks.get(event, []) + user_entries
+settings["hooks"] = merged_hooks
+
 # Inject AIPASS_HOME into env block so dispatched agents find AIPass
 env_block = settings.get("env", {})
 env_block["AIPASS_HOME"] = repo_root