diff --git a/CLI/CLI+Hooks.swift b/CLI/CLI+Hooks.swift
index 1172a8121..7cd845221 100644
--- a/CLI/CLI+Hooks.swift
+++ b/CLI/CLI+Hooks.swift
@@ -1975,10 +1975,13 @@ extension ProgramaCLI {
         }
         if rawHooks == nil, !install { return root }
         var hooks = rawHooks as? [String: Any] ?? [:]
+        var updatedEvents = Set<String>()
         for event in Array(hooks.keys) {
             guard let rawGroups = hooks[event] as? [Any] else {
                 throw CodexHooksError(message: "hooks.json event \(event) must be an array")
             }
+            // Trust keys are positional: rewrite Programa's first handler in place; a sole-handler group drops stale matchers.
+            let spec = install ? Self.codexHookSpecs.first { $0.event == event } : nil
             var rewritten: [[String: Any]] = []
             for (groupIndex, rawGroup) in rawGroups.enumerated() {
                 guard var group = rawGroup as? [String: Any] else {
@@ -1996,31 +1999,28 @@ extension ProgramaCLI {
                         throw CodexHooksError(message: "hooks.json \(event) handler \(handlerIndex).command must be a string")
                     }
                     if !codexIsOwnedHandler(handler, event: event) { handlers.append(handler) }
+                    else if let spec, updatedEvents.insert(event).inserted { handlers.append(Self.codexCanonicalHandler(spec)) }
                 }
                 if !handlers.isEmpty {
+                    if rawHandlers.count == 1, codexIsOwnedHandler(handlers[0], event: event) { group = [:] }
                     group["hooks"] = handlers
                     rewritten.append(group)
                 }
             }
-            if rewritten.isEmpty { hooks.removeValue(forKey: event) }
-            else { hooks[event] = rewritten }
+            hooks[event] = rewritten.isEmpty ? nil : rewritten
         }
-        if install {
-            for spec in Self.codexHookSpecs {
-                var groups = hooks[spec.event] as? [[String: Any]] ?? []
-                groups.append(["hooks": [[
-                    "type": "command",
-                    "command": Self.codexHookCommand(spec.commandEvent),
-                    "timeout": spec.timeout,
-                ] as [String: Any]]])
-                hooks[spec.event] = groups
-            }
+        for spec in Self.codexHookSpecs where install && !updatedEvents.contains(spec.event) {
+            hooks[spec.event] = (hooks[spec.event] as? [[String: Any]] ?? []) + [["hooks": [Self.codexCanonicalHandler(spec)]]]
         }
         root["hooks"] = hooks
         try codexValidateForeignHandlerPositions(before: source, after: root)
         return root
     }
 
+    private static func codexCanonicalHandler(_ spec: CodexHookSpec) -> [String: Any] {
+        ["type": "command", "command": codexHookCommand(spec.commandEvent), "timeout": spec.timeout]
+    }
+
     private func codexValidateForeignHandlerPositions(
         before: [String: Any],
         after: [String: Any]
diff --git a/tests/test_cli_codex_hook_trust.py b/tests/test_cli_codex_hook_trust.py
index 7aa788174..e5e55b753 100644
--- a/tests/test_cli_codex_hook_trust.py
+++ b/tests/test_cli_codex_hook_trust.py
@@ -370,17 +370,18 @@ def test_invalid_config_fails_before_hooks_are_mutated(self) -> None:
                 )
 
     def test_install_refuses_to_reassign_a_foreign_positional_trust_key(self) -> None:
-        """Removing a legacy group must not shift foreign trust onto Programa's replacement."""
+        """Dropping a duplicate Programa group must not shift foreign trust positions."""
         hooks = {
             "hooks": {
                 "Stop": [
+                    {"hooks": [owned_handler("stop")]},
                     {"hooks": [owned_handler("stop")]},
                     {"hooks": [foreign_handler("position-sensitive-stop")]},
                 ]
             }
         }
         original_hooks = self.write_hooks(hooks)
-        foreign_key = f"{self.codex_home.resolve() / 'hooks.json'}:stop:1:0"
+        foreign_key = f"{self.codex_home.resolve() / 'hooks.json'}:stop:2:0"
         original_config = (
             f'[hooks.state.{json.dumps(foreign_key)}]\n'
             'trusted_hash = "sha256:foreign-position"\n'
@@ -397,6 +398,40 @@ def test_install_refuses_to_reassign_a_foreign_positional_trust_key(self) -> Non
         self.assertEqual((self.codex_home / "hooks.json").read_bytes(), original_hooks)
         self.assertEqual((self.codex_home / "config.toml").read_bytes(), original_config)
 
+    def test_reinstall_updates_programa_in_place_when_foreign_groups_follow_it(self) -> None:
+        """A later tool's groups must keep their positions across a Programa reinstall."""
+        foreign_command = (
+            'bun --no-env-file "/x/darkroom/source/src/scripts/codex-hook.ts" '
+            '"src/hooks/session-end.ts"'
+        )
+        hooks: dict[str, Any] = {"hooks": {}}
+        for event, command_event in (
+            ("SessionEnd", "session-end"),
+            ("UserPromptSubmit", "prompt-submit"),
+        ):
+            hooks["hooks"][event] = [
+                {"hooks": [owned_handler(command_event)]},
+                {"hooks": [{"type": "command", "command": foreign_command, "timeout": 5}]},
+            ]
+        self.write_hooks(hooks)
+
+        install = self.run_cli("install-hooks")
+        self.assert_succeeded(install)
+
+        installed = self.read_hooks()["hooks"]
+        for event in ("SessionEnd", "UserPromptSubmit"):
+            groups = installed[event]
+            self.assertEqual(len(groups), 2, f"{event} must not gain or lose groups")
+            self.assertTrue(
+                is_programa_handler(event, groups[0]["hooks"][0]["command"]),
+                f"{event} Programa handler must stay at 0:0",
+            )
+            self.assertEqual(
+                groups[1]["hooks"],
+                [{"type": "command", "command": foreign_command, "timeout": 5}],
+                f"{event} foreign handler must stay at 1:0",
+            )
+
     def test_uninstall_refuses_to_delete_a_user_comment_with_stale_trust(self) -> None:
         """A positional trust table cannot own comments that follow its assignments."""
         hooks = {"hooks": {"SessionStart": [{"hooks": [owned_handler("session-start")]}]}}