hooks: answer each message, so the extension sends a report once

the pi extension (herdr's protocol) waits for a reply line and sends a
report again after 0.5 s without one; dingger never replied. every report
arrived twice and took about 2 s, delaying the next one (the live log: 196
of 400 reports repeated the previous one, 0.49 s later). the daemon now
answers each line with {"ok":true}; senders that do not read replies
(dingger poke, importance, the claude hook) are unaffected.

e2e step 21: one report, done in 0.38 s; without replies, two, 2.08 s.

1 files changed, 12 insertions, 0 deletions

diff --git a/crates/dinggerd/src/hooks.rs b/crates/dinggerd/src/hooks.rs
index 8b24659..a649fa0 100644
--- a/crates/dinggerd/src/hooks.rs
+++ b/crates/dinggerd/src/hooks.rs
@@ -18,6 +18,8 @@
 //! order, so a turn that starts and finishes between two polls is still a
 //! completion, and each report wakes the watcher immediately.
 //!
+//! Each line is answered with `{"ok":true}`.
+//!
 //! `{"method":"poke"}` only wakes the watcher; `dingger focus` and tmux's
 //! focus-change hooks send it so attendance updates without waiting for the
 //! next poll. The last reported state stays authoritative for its pane
@@ -123,8 +125,18 @@ struct HookParams {
 }
 
 fn handle_stream(stream: UnixStream) {
+    // Each message gets a reply line: an extension waits for one and sends
+    // the message again without it (herdr's protocol), so a report would
+    // arrive twice and take seconds.
+    let mut replies = stream.try_clone().ok();
     for line in BufReader::new(stream).lines() {
         let Ok(line) = line else { return };
+        if let Some(out) = replies.as_mut() {
+            use std::io::Write;
+            if out.write_all(b"{\"ok\":true}\n").is_err() {
+                replies = None; // the sender does not read replies
+            }
+        }
         let Ok(message) = serde_json::from_str::<HookMessage>(&line) else {
             warn!(%line, "invalid hook message");
             continue;