Emit valid JSON objects for Codex hook reports

plugins/disk-hygiene/hooks/disk_hygiene.py

@@ -23,6 +23,7 @@
 )
 from cleanup_registry import Protected, registry
 from cleanup_switch import cleanup_enabled
+from hook_output import protocol_output
 
 
 def parse_args():
@@ -111,7 +112,7 @@ def main():
             "explicit session identity is required; no ownership inferred from cwd"
         )
     result = run_command(args, payload)
-    print(json.dumps(result))
+    print(json.dumps(protocol_output(args, result)))
 
 
 def run_command(args, payload):

plugins/disk-hygiene/hooks/hook_output.py

@@ -0,0 +1,19 @@
+"""Codex hook objects. Source: https://learn.chatgpt.com/docs/hooks"""
+
+import json
+
+
+def protocol_output(args, result):
+    if args.host != "codex" or args.command != "hook" or not isinstance(result, list):
+        return result
+    if not result:
+        return {}
+    report = json.dumps(result)
+    if args.event == "PostToolUse":
+        return {
+            "hookSpecificOutput": {
+                "hookEventName": args.event,
+                "additionalContext": report,
+            }
+        }
+    return {"systemMessage": report}

tests/test_hook_output_protocol.py

@@ -0,0 +1,63 @@
+"""Codex output regression. Source: https://learn.chatgpt.com/docs/hooks"""
+
+import importlib
+import io
+import json
+from pathlib import Path
+from types import SimpleNamespace
+
+import pytest
+
+
+@pytest.mark.parametrize(
+    "host,command,event,result,expected",
+    [
+        ("codex", "hook", "PostToolUse", [], {}),
+        ("codex", "hook", "Stop", [], {}),
+        (
+            "codex",
+            "hook",
+            "PostToolUse",
+            [{"protected": "active process"}],
+            {
+                "hookSpecificOutput": {
+                    "hookEventName": "PostToolUse",
+                    "additionalContext": '[{"protected": "active process"}]',
+                }
+            },
+        ),
+        (
+            "codex",
+            "hook",
+            "Stop",
+            [{"removed": "owned path"}],
+            {"systemMessage": '[{"removed": "owned path"}]'},
+        ),
+        (
+            "codex",
+            "hook",
+            "Stop",
+            {"decision": "block", "reason": "pending"},
+            {"decision": "block", "reason": "pending"},
+        ),
+        ("claude", "hook", "PostToolUse", [], []),
+        ("codex", "status", None, [], []),
+    ],
+)
+def test_main_emits_host_protocol(
+    monkeypatch, capsys, host, command, event, result, expected
+):
+    monkeypatch.syspath_prepend(
+        str(Path(__file__).resolve().parents[1] / "plugins/disk-hygiene/hooks")
+    )
+    module = importlib.import_module("disk_hygiene")
+    args = SimpleNamespace(
+        host=host, command=command, event=event, session="test-session"
+    )
+    monkeypatch.setattr(module, "parse_args", lambda: args)
+    monkeypatch.setattr(module, "cleanup_enabled", lambda: True)
+    monkeypatch.setattr(module.transcript_policy, "delete_enabled", lambda: False)
+    monkeypatch.setattr(module, "run_command", lambda *args: result)
+    monkeypatch.setattr(module.sys, "stdin", io.StringIO("{}"))
+    module.main()
+    assert json.loads(capsys.readouterr().out) == expected