diff --git a/src/agent_comms_hooks/__init__.py b/src/agent_comms_hooks/__init__.py
index 0efb22ae2c..7ee7a49d3e 100644
--- a/src/agent_comms_hooks/__init__.py
+++ b/src/agent_comms_hooks/__init__.py
@@ -15,6 +15,7 @@
 from abc import ABC, abstractmethod
 from collections.abc import Mapping
 from dataclasses import dataclass, fields
+from functools import cache
 from importlib import import_module
 from importlib.metadata import entry_points
 from pathlib import Path
@@ -127,13 +128,30 @@ def console_script(target: str) -> str:
 
     @classmethod
     def owns_entry(cls, entry: Mapping[str, object]) -> bool:
-        """Ownership survives deletion of a program and its console script."""
-        return entry.get("writer") == cls.writer
+        """Ownership survives deletion of a program and its console script. An untagged
+        entry running only this package's hooks was written before the tag existed;
+        install adopts it, so each hook keeps one entry."""
+        match entry:
+            case {"writer": writer} if writer == cls.writer:
+                return True
+            case {"hooks": [_, *_] as hooks}:
+                return all(hook in cls.hooks() for hook in hooks)
+        return False
+
+    @classmethod
+    @cache
+    def hooks(cls) -> tuple[dict[str, str], ...]:
+        """The hook every declared program installs."""
+        return tuple(program.hook() for program in cls.members())
+
+    @classmethod
+    def hook(cls) -> dict[str, str]:
+        return {"type": "command", "command": cls.command()}
 
     @classmethod
     def entry(cls) -> dict[str, object]:
         """This program's entry, marked so install can replace what it wrote."""
-        return {"writer": cls.writer, "hooks": [{"type": "command", "command": cls.command()}]}
+        return {"writer": cls.writer, "hooks": [cls.hook()]}
 
 
 class ClaudeToolHookProgram(ClaudeHookProgram, ABC):
diff --git a/tests/test_claude_hook_install.py b/tests/test_claude_hook_install.py
new file mode 100644
index 0000000000..9d5639c732
--- /dev/null
+++ b/tests/test_claude_hook_install.py
@@ -0,0 +1,37 @@
+"""Install owns every Claude Code hook entry that runs its programs, tagged or not."""
+
+import json
+
+from agent_comms.harness_install import ClaudeCodeHarness
+from agent_comms_hooks import ClaudeHookProgram
+
+FOREIGN = {"matcher": "Bash", "hooks": [{"type": "command", "command": "python3 -I guard.py"}]}
+
+
+def commands(settings) -> dict[str, list[str]]:
+    hooks = json.loads(settings.read_text())["hooks"]
+    return {
+        event: sorted(hook["command"] for entry in entries for hook in entry["hooks"])
+        for event, entries in hooks.items()
+    }
+
+
+def test_install_adopts_untagged_copies_of_its_hooks_and_keeps_foreign_ones(tmp_path):
+    settings = tmp_path / ".claude/settings.json"
+    untagged: dict[str, list[dict[str, object]]] = {"PreToolUse": [FOREIGN]}
+    for program in ClaudeHookProgram.members():
+        entry = {key: value for key, value in program.entry().items() if key != "writer"}
+        for event in program.events:
+            untagged.setdefault(event, []).append(entry)
+    settings.parent.mkdir()
+    settings.write_text(json.dumps({"hooks": untagged, "theme": "dark"}))
+
+    ClaudeCodeHarness(tmp_path).configure()
+    ClaudeCodeHarness(tmp_path).configure()
+
+    expected: dict[str, list[str]] = {"PreToolUse": ["python3 -I guard.py"]}
+    for program in ClaudeHookProgram.members():
+        for event in program.events:
+            expected.setdefault(event, []).append(program.command())
+    assert commands(settings) == {event: sorted(found) for event, found in expected.items()}
+    assert json.loads(settings.read_text())["theme"] == "dark"