feat(agent): thread per-tool reasoning through provider, session, and all surfaces (#1513)

* feat(agent): thread per-tool reasoning from LLM through to REPL, HTTP, SSE, and DB

Add end-to-end agent reasoning summaries so users can see *why* the
agent chose specific tools, not just what it did.

- Add `reasoning: Option<String>` to `ToolCall` (all providers)
- Populate from LLM response content in `Reasoning::respond_with_tools`
  and `select_tools`, with per-tool override when providers supply it
- Extend `Turn` with `narrative` and `TurnToolCall` with `rationale` +
  `tool_call_id` for identity-based result matching
- Persist reasoning in DB via existing tool_calls JSON (no migration)
- Add `StatusUpdate::ReasoningUpdate` and `SseEvent::ReasoningUpdate` +
  `SseEvent::JobReasoning` for real-time streaming
- Emit reasoning events in both chat dispatcher and worker job path
- Add `/reasoning [N|all]` command for inspecting turn reasoning
- Surface `narrative` and `rationale` in HTTP `/api/chat/history`

Based on the design from #361 and #456, reconstructed cleanly with
Option<String> to minimize blast radius (vs mandatory String that broke
compilation in #456).

Closes #456

Co-Authored-By: panosAthDBX <[email protected]>
Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* fix: address PR review feedback from Gemini and Copilot

- Fix `_ => Ok(None)` in agent_loop.rs to avoid accidental shutdown
- Fix fallback in record_tool_result_for/record_tool_error_for to use
  first pending call instead of last_mut (parallel execution safety)
- Include per-tool decisions in WASM channel reasoning messages
- Apply truncate_at_tool_tags + clean_response to shared_reasoning in
  select_tools (parity with respond_with_tools)
- Persist turn-level narrative to DB in tool_calls JSON wrapper
- Parse both old (array) and new (object) tool_calls formats in
  build_turns_from_db_messages for backward compatibility
- Populate reasoning from action.reasoning in execute_plan ToolCalls

[skip-regression-check]

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* fix: address second round of review comments + merge fixes

- Add reasoning: None to new github_copilot.rs ToolCall sites (from staging merge)
- Run cargo fmt on 4 files with formatting diffs
- Truncate narrative to 1000 chars before DB persistence
- Clone turn data and drop session lock in /reasoning command
- Extract ToolDecisionDto::from_json_array shared helper (deduplicate
  worker/job.rs and orchestrator/api.rs)
- Add unit tests for wrapped tool_calls JSON format with narrative

[skip-regression-check]

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* fix: address third round of review comments (Copilot + serrrfirat)

- Reword ToolCall.reasoning docstring to reflect provider-supplied or
  fallback contract
- Sanitize narrative through SafetyLayer before storage/emission
- Clean per-tool reasoning via truncate_at_tool_tags + clean_response
  in select_tools (parity with shared reasoning)
- Convert 4 approval-path recording sites in thread_ops.rs to
  identity-based record_tool_result_for/record_tool_error_for
- Preserve tool_call_id and reasoning through restore_from_messages
- Fix has_result/has_error to reject JSON null values
- Truncate tool_call_id to 128 chars before DB persistence
- Add 4 unit tests for record_tool_result_for/error_for edge cases

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* fix: address zmanian review — sanitize JobDelegate reasoning + warn on dropped results

- Sanitize narrative and per-tool rationale through SafetyLayer in
  JobDelegate reasoning events (parity with ChatDelegate)
- Add tracing::warn when record_tool_result_for/error_for drops a
  result because no matching or pending tool call exists
- Add 3 unit tests for reasoning normalization (thinking tags,
  tool tags, empty-after-cleaning)

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* fix: address 4 remaining unreplied review comments

- Clean per-tool reasoning in respond_with_tools via truncate_at_tool_tags
  + clean_response (parity with select_tools)
- Handle wrapped JSON format in rebuild_chat_messages_from_db so cold
  hydration works after persist_tool_calls format change
- Update persist_tool_calls doc comment to describe new JSON shape
- Sanitize per-tool rationale through SafetyLayer in ChatDelegate before
  emission and storage (parity with JobDelegate)

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* fix: address zmanian review round 2

- Add tracing::debug on fallback-to-pending path in record_tool_result_for
  and record_tool_error_for (item 1)
- Add comment explaining why /reasoning is special-cased in agent_loop.rs
  (item 4)
- Items 2 (narrative persistence), 3 (rationale sanitization), and 5
  (catch-all fix) were already addressed in prior commits

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

---------

Co-authored-by: panosAthDBX <[email protected]>
Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]>

src/channels/channel.rs

@@ -265,6 +265,15 @@ impl OutgoingResponse {
     }
 }
 
+/// A single tool decision within a reasoning update.
+#[derive(Debug, Clone)]
+pub struct ToolDecision {
+    /// Tool name.
+    pub tool_name: String,
+    /// Agent's reasoning for choosing this tool.
+    pub rationale: String,
+}
+
 /// Status update types for showing agent activity.
 #[derive(Debug, Clone)]
 pub enum StatusUpdate {
@@ -333,6 +342,13 @@ pub enum StatusUpdate {
     },
     /// Suggested follow-up messages for the user.
     Suggestions { suggestions: Vec<String> },
+    /// Agent reasoning update (why it chose specific tools).
+    ReasoningUpdate {
+        /// Human-readable summary of the agent's decision.
+        narrative: String,
+        /// Per-tool decisions.
+        decisions: Vec<ToolDecision>,
+    },
     /// Per-turn token usage and cost summary (shown as subtle metadata).
     TurnCost {
         input_tokens: u64,

src/channels/mod.rs

@@ -39,7 +39,7 @@ mod webhook_server;
 
 pub use channel::{
     AttachmentKind, Channel, ChannelSecretUpdater, IncomingAttachment, IncomingMessage,
-    MessageStream, OutgoingResponse, StatusUpdate, routing_target_from_metadata,
+    MessageStream, OutgoingResponse, StatusUpdate, ToolDecision, routing_target_from_metadata,
 };
 pub use http::{HttpChannel, HttpChannelState};
 pub use manager::ChannelManager;

src/channels/repl.rs

@@ -75,6 +75,7 @@ const SLASH_COMMANDS: &[&str] = &[
     "/suggest",
     "/thread",
     "/resume",
+    "/reasoning",
 ];
 
 /// Rustyline helper for slash-command tab completion.
@@ -841,6 +842,19 @@ impl Channel for ReplChannel {
             StatusUpdate::Suggestions { .. } => {
                 // Suggestions are only rendered by the web gateway
             }
+            StatusUpdate::ReasoningUpdate {
+                narrative,
+                decisions,
+            } => {
+                if !narrative.is_empty() {
+                    let display = truncate_for_preview(&narrative, CLI_STATUS_MAX);
+                    eprintln!("  \x1b[94m\u{25B6} {display}\x1b[0m");
+                }
+                for d in &decisions {
+                    let display = truncate_for_preview(&d.rationale, CLI_STATUS_MAX);
+                    eprintln!("    \x1b[90m\u{2192} {}: {display}\x1b[0m", d.tool_name);
+                }
+            }
             StatusUpdate::TurnCost { .. } => {
                 // Cost display is handled by the TUI channel
             }

src/channels/wasm/wrapper.rs

@@ -3061,6 +3061,20 @@ fn status_to_wit(
         },
         // Suggestions and turn cost are web-gateway-only; skip for WASM channels
         StatusUpdate::Suggestions { .. } | StatusUpdate::TurnCost { .. } => return None,
+        StatusUpdate::ReasoningUpdate {
+            narrative,
+            decisions,
+        } => {
+            let mut msg = narrative.clone();
+            for d in decisions {
+                msg.push_str(&format!("\n  → {}: {}", d.tool_name, d.rationale));
+            }
+            wit_channel::StatusUpdate {
+                status: wit_channel::StatusType::Status,
+                message: msg,
+                metadata_json,
+            }
+        }
     })
 }
 

src/channels/web/handlers/chat.rs

@@ -398,8 +398,10 @@ pub async fn chat_history_handler(
                                 truncate_preview(&s, 500)
                             }),
                             error: tc.error.clone(),
+                            rationale: tc.rationale.clone(),
                         })
                         .collect(),
+                    narrative: t.narrative.clone(),
                 })
                 .collect();
 

src/channels/web/mod.rs

@@ -489,6 +489,20 @@ impl Channel for GatewayChannel {
             },
             StatusUpdate::Suggestions { suggestions } => AppEvent::Suggestions {
                 suggestions,
+                thread_id: thread_id.clone(),
+            },
+            StatusUpdate::ReasoningUpdate {
+                narrative,
+                decisions,
+            } => AppEvent::ReasoningUpdate {
+                narrative,
+                decisions: decisions
+                    .into_iter()
+                    .map(|d| crate::channels::web::types::ToolDecisionDto {
+                        tool_name: d.tool_name,
+                        rationale: d.rationale,
+                    })
+                    .collect(),
                 thread_id,
             },
             StatusUpdate::TurnCost {

src/channels/web/openai_compat.rs

@@ -231,6 +231,7 @@ pub fn convert_messages(messages: &[OpenAiMessage]) -> Result<Vec<ChatMessage>,
                                 name: tc.function.name.clone(),
                                 arguments: serde_json::from_str(&tc.function.arguments)
                                     .unwrap_or(serde_json::Value::Object(Default::default())),
+                                reasoning: None,
                             })
                             .collect();
                         Ok(ChatMessage::assistant_with_tool_calls(
@@ -954,6 +955,7 @@ mod tests {
             id: "call_abc".to_string(),
             name: "search".to_string(),
             arguments: serde_json::json!({"query": "rust"}),
+            reasoning: None,
         }];
 
         let converted = convert_tool_calls_to_openai(&calls);

src/channels/web/server.rs

@@ -1725,8 +1725,10 @@ async fn chat_history_handler(
                             truncate_preview(&s, 500)
                         }),
                         error: tc.error.clone(),
+                        rationale: tc.rationale.clone(),
                     })
                     .collect(),
+                narrative: t.narrative.clone(),
             })
             .collect();
 

src/channels/web/types.rs

@@ -63,6 +63,9 @@ pub struct TurnInfo {
     pub started_at: String,
     pub completed_at: Option<String>,
     pub tool_calls: Vec<ToolCallInfo>,
+    /// Agent's reasoning narrative for this turn.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub narrative: Option<String>,
 }
 
 #[derive(Debug, Serialize)]
@@ -74,6 +77,9 @@ pub struct ToolCallInfo {
     pub result_preview: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub error: Option<String>,
+    /// Agent's reasoning for choosing this tool.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub rationale: Option<String>,
 }
 
 #[derive(Debug, Serialize)]
@@ -116,7 +122,7 @@ pub struct ApprovalRequest {
 
 // --- App Event (re-exported from ironclaw_common) ---
 
-pub use ironclaw_common::AppEvent;
+pub use ironclaw_common::{AppEvent, ToolDecisionDto};
 
 // --- Memory ---
 

src/channels/web/util.rs

@@ -4,6 +4,21 @@ use crate::channels::web::types::{ToolCallInfo, TurnInfo};
 
 pub use ironclaw_common::truncate_preview;
 
+/// Parse tool call summary JSON objects into `ToolCallInfo` structs.
+fn parse_tool_call_infos(calls: &[serde_json::Value]) -> Vec<ToolCallInfo> {
+    calls
+        .iter()
+        .map(|c| ToolCallInfo {
+            name: c["name"].as_str().unwrap_or("unknown").to_string(),
+            has_result: c.get("result_preview").is_some_and(|v| !v.is_null()),
+            has_error: c.get("error").is_some_and(|v| !v.is_null()),
+            result_preview: c["result_preview"].as_str().map(String::from),
+            error: c["error"].as_str().map(String::from),
+            rationale: c["rationale"].as_str().map(String::from),
+        })
+        .collect()
+}
+
 /// Build TurnInfo pairs from flat DB messages (user/tool_calls/assistant triples).
 ///
 /// Handles three message patterns:
@@ -27,6 +42,7 @@ pub fn build_turns_from_db_messages(
                 started_at: msg.created_at.to_rfc3339(),
                 completed_at: None,
                 tool_calls: Vec::new(),
+                narrative: None,
             };
 
             // Check if next message is a tool_calls record
@@ -34,18 +50,28 @@ pub fn build_turns_from_db_messages(
                 && next.role == "tool_calls"
             {
                 let tc_msg = iter.next().expect("peeked");
-                match serde_json::from_str::<Vec<serde_json::Value>>(&tc_msg.content) {
-                    Ok(calls) => {
-                        turn.tool_calls = calls
-                            .iter()
-                            .map(|c| ToolCallInfo {
-                                name: c["name"].as_str().unwrap_or("unknown").to_string(),
-                                has_result: c.get("result_preview").is_some(),
-                                has_error: c.get("error").is_some(),
-                                result_preview: c["result_preview"].as_str().map(String::from),
-                                error: c["error"].as_str().map(String::from),
-                            })
-                            .collect();
+                // Parse tool_calls JSON — supports two formats:
+                // safety: no byte-index slicing; comment describes JSON shape
+                match serde_json::from_str::<serde_json::Value>(&tc_msg.content) {
+                    Ok(serde_json::Value::Array(calls)) => {
+                        // Old format: plain array
+                        turn.tool_calls = parse_tool_call_infos(&calls);
+                    }
+                    Ok(serde_json::Value::Object(obj)) => {
+                        // New wrapped format with narrative
+                        turn.narrative = obj
+                            .get("narrative")
+                            .and_then(|v| v.as_str())
+                            .map(String::from);
+                        if let Some(serde_json::Value::Array(calls)) = obj.get("calls") {
+                            turn.tool_calls = parse_tool_call_infos(calls);
+                        }
+                    }
+                    Ok(_) => {
+                        tracing::warn!(
+                            message_id = %tc_msg.id,
+                            "Unexpected tool_calls JSON shape in DB, skipping"
+                        );
                     }
                     Err(e) => {
                         tracing::warn!(
@@ -83,6 +109,7 @@ pub fn build_turns_from_db_messages(
                 started_at: msg.created_at.to_rfc3339(),
                 completed_at: Some(msg.created_at.to_rfc3339()),
                 tool_calls: Vec::new(),
+                narrative: None,
             });
             turn_number += 1;
         }
@@ -201,4 +228,52 @@ mod tests {
         assert!(turns[0].tool_calls.is_empty());
         assert_eq!(turns[0].state, "Completed");
     }
+
+    #[test]
+    fn test_build_turns_with_wrapped_tool_calls_format() {
+        let tc_json = serde_json::json!({
+            "narrative": "Searching memory for context before proceeding.",
+            "calls": [
+                {"name": "memory_search", "result_preview": "found 3 items", "rationale": "consult prior context"},
+                {"name": "shell", "error": "permission denied"}
+            ]
+        });
+        let messages = vec![
+            make_msg("user", "Find info", 0),
+            make_msg("tool_calls", &tc_json.to_string(), 500),
+            make_msg("assistant", "Here's what I found", 1000),
+        ];
+        let turns = build_turns_from_db_messages(&messages);
+        assert_eq!(turns.len(), 1);
+        assert_eq!(
+            turns[0].narrative.as_deref(),
+            Some("Searching memory for context before proceeding.")
+        );
+        assert_eq!(turns[0].tool_calls.len(), 2);
+        assert_eq!(turns[0].tool_calls[0].name, "memory_search");
+        assert_eq!(
+            turns[0].tool_calls[0].rationale.as_deref(),
+            Some("consult prior context")
+        );
+        assert!(turns[0].tool_calls[0].has_result);
+        assert_eq!(turns[0].tool_calls[1].name, "shell");
+        assert!(turns[0].tool_calls[1].has_error);
+        assert_eq!(turns[0].response.as_deref(), Some("Here's what I found"));
+    }
+
+    #[test]
+    fn test_build_turns_wrapped_format_without_narrative() {
+        let tc_json = serde_json::json!({
+            "calls": [{"name": "echo", "result_preview": "hello"}]
+        });
+        let messages = vec![
+            make_msg("user", "Say hi", 0),
+            make_msg("tool_calls", &tc_json.to_string(), 500),
+            make_msg("assistant", "Done", 1000),
+        ];
+        let turns = build_turns_from_db_messages(&messages);
+        assert_eq!(turns.len(), 1);
+        assert!(turns[0].narrative.is_none());
+        assert_eq!(turns[0].tool_calls.len(), 1);
+    }
 }