feat(ai): surface tool invocations in chat history

load_history now groups preceding tool_call + tool_result scaffolding
under each assistant reply as `tools: [{name, arguments, result}]`.
Result bodies over 2000 chars are truncated for payload size with a
`result_truncated` flag; the full value remains in training_messages.

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

src/ai/insight_chat.rs

@@ -115,10 +115,39 @@ impl InsightChatService {
         let mut rendered = Vec::new();
         let mut user_turns_seen = 0usize;
         let mut assistant_turns_seen = 0usize;
+
+        // Accumulate tool invocations seen since the last user turn. An
+        // invocation is: one assistant tool_call message (which may hold
+        // multiple calls) + the N following tool-role messages (one per call,
+        // in order). They attach to the next assistant-with-content, which
+        // is the "final" reply for the current turn.
+        //
+        // Wire shape from the model:
+        //   assistant { tool_calls: [A, B], content: "" }
+        //   tool      { content: "result of A" }
+        //   tool      { content: "result of B" }
+        //   assistant { content: "here's the answer" }  ← rendered as final
+        let mut pending_tools: Vec<ToolInvocation> = Vec::new();
+        // Queue of (name, arguments) awaiting a tool_result to pair with.
+        let mut pending_calls: std::collections::VecDeque<(String, serde_json::Value)> =
+            std::collections::VecDeque::new();
+
         for msg in &messages {
             match msg.role.as_str() {
                 "system" => continue,
-                "tool" => continue,
+                "tool" => {
+                    if let Some((name, arguments)) = pending_calls.pop_front() {
+                        let (result, result_truncated) = truncate_tool_result(&msg.content);
+                        pending_tools.push(ToolInvocation {
+                            name,
+                            arguments,
+                            result,
+                            result_truncated,
+                        });
+                    }
+                    // If there's no pending call, the tool message is an
+                    // orphan (shouldn't happen in practice) — skip silently.
+                }
                 "assistant" => {
                     let has_tool_calls = msg
                         .tool_calls
@@ -126,22 +155,41 @@ impl InsightChatService {
                         .map(|c| !c.is_empty())
                         .unwrap_or(false);
                     if has_tool_calls && msg.content.trim().is_empty() {
+                        // Tool-dispatch turn: enqueue calls, wait for tool
+                        // results on subsequent messages.
+                        if let Some(ref tcs) = msg.tool_calls {
+                            for tc in tcs {
+                                pending_calls.push_back((
+                                    tc.function.name.clone(),
+                                    tc.function.arguments.clone(),
+                                ));
+                            }
+                        }
                         continue;
                     }
+                    // Final assistant reply for this turn — drain accumulated
+                    // tools into it.
                     assistant_turns_seen += 1;
+                    let tools = std::mem::take(&mut pending_tools);
+                    pending_calls.clear(); // any leftover unpaired calls are dropped
                     rendered.push(RenderedMessage {
                         role: "assistant".to_string(),
                         content: msg.content.clone(),
                         is_initial: false,
+                        tools,
                     });
                 }
                 "user" => {
                     let is_initial = user_turns_seen == 0;
                     user_turns_seen += 1;
+                    // New user turn resets any in-flight tool state.
+                    pending_tools.clear();
+                    pending_calls.clear();
                     rendered.push(RenderedMessage {
                         role: "user".to_string(),
                         content: msg.content.clone(),
                         is_initial,
+                        tools: Vec::new(),
                     });
                 }
                 _ => continue,
@@ -609,6 +657,38 @@ pub struct RenderedMessage {
     pub role: String,
     pub content: String,
     pub is_initial: bool,
+    /// Tools invoked during this turn (only populated for assistant replies).
+    /// Empty for user messages and for assistant replies that didn't involve
+    /// tool calls.
+    pub tools: Vec<ToolInvocation>,
+}
+
+#[derive(Debug, Clone)]
+pub struct ToolInvocation {
+    pub name: String,
+    pub arguments: serde_json::Value,
+    pub result: String,
+    /// True when `result` was trimmed for payload size. Full value remains
+    /// available in the raw training_messages blob.
+    pub result_truncated: bool,
+}
+
+/// Soft cap for tool-result bodies returned via the history API. Keeps
+/// payloads small for the mobile client — verbose SMS / geocoding responses
+/// don't need to ship in full for inspection.
+const TOOL_RESULT_PREVIEW_MAX: usize = 2000;
+
+fn truncate_tool_result(s: &str) -> (String, bool) {
+    if s.len() <= TOOL_RESULT_PREVIEW_MAX {
+        (s.to_string(), false)
+    } else {
+        // Cut on a char boundary.
+        let mut cut = TOOL_RESULT_PREVIEW_MAX;
+        while !s.is_char_boundary(cut) && cut > 0 {
+            cut -= 1;
+        }
+        (s[..cut].to_string(), true)
+    }
 }
 
 /// Trim history to fit within `budget_bytes` of serialized JSON. Preserves