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/orchestrator/api.rs

@@ -14,6 +14,7 @@ use serde::{Deserialize, Serialize};
 use tokio::sync::{Mutex, broadcast};
 use uuid::Uuid;
 
+use crate::channels::web::types::ToolDecisionDto;
 use crate::db::Database;
 use crate::llm::{CompletionRequest, LlmProvider, ToolCompletionRequest};
 use crate::orchestrator::auth::{TokenStore, worker_auth_middleware};
@@ -344,6 +345,20 @@ async fn job_event_handler(
             // gain context/memory tracking capabilities.
             fallback_deliverable: payload.data.get("fallback_deliverable").cloned(),
         },
+        "reasoning" => {
+            let narrative = payload
+                .data
+                .get("narrative")
+                .and_then(|v| v.as_str())
+                .unwrap_or("")
+                .to_string();
+            let decisions = ToolDecisionDto::from_json_array(&payload.data["decisions"]);
+            AppEvent::JobReasoning {
+                job_id: job_id_str,
+                narrative,
+                decisions,
+            }
+        }
         _ => AppEvent::JobStatus {
             job_id: job_id_str,
             message: payload