chat: route search_messages({date}) to get_sms_messages

When the LLM calls search_messages with { date, limit } and no
query, it's making the predictable mistake of conflating the two
"messages"-shaped tools. The previous behaviour returned an error
that pointed it at get_sms_messages — correct, but burning a turn
on the misroute. Long photo-chat threads where the user asks
"what was happening that weekend?" hit this on small models
roughly half the time.

Now the date-string-without-query case transparently dispatches
to get_sms_messages with the same args (date / limit / days_radius
/ contact name all pass through unchanged) and prepends a short
"(Note: routed to get_sms_messages — prefer it directly next time)"
to the result. The model sees real data on its first try while
still learning the right tool for next time. Cases that don't have
a get_sms_messages equivalent (numeric contact_id, or start_ts /
end_ts windows) keep the original error so the model knows to
either supply a query or restructure its call.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ai/insight_generator.rs

@@ -1558,7 +1558,7 @@ Return ONLY the summary, nothing else."#,
     ) -> String {
         let result = match tool_name {
             "search_rag" => self.tool_search_rag(arguments, ollama, cx).await,
-            "search_messages" => self.tool_search_messages(arguments).await,
+            "search_messages" => self.tool_search_messages(arguments, cx).await,
             "get_sms_messages" => self.tool_get_sms_messages(arguments, cx).await,
             "get_calendar_events" => self.tool_get_calendar_events(arguments, cx).await,
             "get_location_history" => self.tool_get_location_history(arguments, cx).await,
@@ -1807,15 +1807,43 @@ Return ONLY the summary, nothing else."#,
     /// Tool: search_messages — keyword / semantic / hybrid search over all
     /// SMS message bodies via the Django FTS5 + embeddings pipeline. Now
     /// supports optional `contact_id`, `start_ts`, `end_ts` filters.
-    async fn tool_search_messages(&self, args: &serde_json::Value) -> String {
+    async fn tool_search_messages(&self, args: &serde_json::Value, cx: &opentelemetry::Context) -> String {
         let query = match args.get("query").and_then(|v| v.as_str()) {
             Some(q) if !q.trim().is_empty() => q.trim(),
             _ => {
-                let has_date = args.get("date").is_some()
+                // Common LLM mistake: calling search_messages with
-                    || args.get("start_ts").is_some()
+                // { date, ... } as if it were date-browsing. The two
-                    || args.get("end_ts").is_some();
+                // tools share the "messages" word, and search_messages
-                let has_contact = args.get("contact").is_some() || args.get("contact_id").is_some();
+                // sounds like the natural verb. Instead of returning
-                if has_date || has_contact {
+                // an error and burning a turn, transparently route to
+                // get_sms_messages when there's a `date` (and a
+                // contact-name string, optional). The LLM gets real
+                // data on its first try; the result is logged with a
+                // routing note so a human reading the trace can see
+                // what happened.
+                let has_date_str = args
+                    .get("date")
+                    .and_then(|v| v.as_str())
+                    .map(|s| !s.trim().is_empty())
+                    .unwrap_or(false);
+                let has_numeric_contact = args.get("contact_id").is_some();
+                let has_ts_window =
+                    args.get("start_ts").is_some() || args.get("end_ts").is_some();
+                if has_date_str && !has_numeric_contact && !has_ts_window {
+                    log::info!(
+                        "search_messages with `date` and no `query` — routing to get_sms_messages"
+                    );
+                    let routed = self.tool_get_sms_messages(args, cx).await;
+                    return format!(
+                        "(Note: routed to get_sms_messages — search_messages requires a \
+                         `query`; date-only browsing belongs on get_sms_messages. Prefer \
+                         get_sms_messages directly next time.)\n\n{}",
+                        routed
+                    );
+                }
+                let has_contact_name =
+                    args.get("contact").and_then(|v| v.as_str()).is_some();
+                if has_ts_window || has_numeric_contact || has_contact_name {
                     return "Error: search_messages needs a 'query' (keywords/phrase). \
                             To fetch messages around a date or from a contact without keywords, \
                             call get_sms_messages with { date, contact? } instead."