refactor: DRY cleanup — extract shared helpers, remove duplication across tools, LSP, overlays, and runtime

Eliminate ~500 lines of duplicate code across 31 files by extracting
shared functions, helpers, and consolidating repeated patterns.

Highlights:
- Toast helpers (toast_info/success/warning/error) on AppStateRest
- push_event() helper for turn-event queue (19 callers consolidated)
- log_write_edit_tool() shared fn (turn.rs + engine.rs ~50 lines saved)
- resolve_api_key() shared fn (spawn.rs + provider.rs)
- LSP call_positional() helper on LspClient
- lsp_cursor_params() shared schema for 4 tool files
-overlay_block() helper for consistent overlay title/border styling
- cycle_selected_index(), path_not_found/a_directory() helpers
- mark_dirty(), save_settings() on AppStateRest
- Remove redundant Err(e) => Err(e) arms in LSP tools
- Consolidate generate_workspace_tree (turn.rs → workspace.rs)
- Simplify background-review wrapper args in auto/mod.rs

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/zesdex-backend/src/app/subagent/auto/mod.rs

@@ -248,16 +248,24 @@ fn spawn_background_review(
     });
 }
 
+/// Collect the trailing arguments shared by all background-review spawners.
+fn review_args<'a>(
+    file_paths: &'a [String],
+    session_dir: &'a Path,
+    workspaces: &'a [std::path::PathBuf],
+    turn_events: &'a Arc<Mutex<VecDeque<TurnEvent>>>,
+    abort_flag: Arc<AtomicBool>,
+) -> (Vec<String>, std::path::PathBuf, Vec<std::path::PathBuf>, Arc<Mutex<VecDeque<TurnEvent>>>, Arc<AtomicBool>) {
+    (
+        file_paths.to_vec(),
+        session_dir.to_path_buf(),
+        workspaces.to_vec(),
+        turn_events.clone(),
+        abort_flag,
+    )
+}
+
 /// Spawn a background subagent that generates tests for modified files.
-///
-/// Uses the test-generator prompt and has read-write access so it can
-/// create test files. Runs in a separate OS thread and reports completion
-/// via `TurnEvent::SystemNote { kind: "bg-test-gen" }`.
-///
-/// Skipped (no-op) if a test-gen run is already in flight (guarded by
-/// `TEST_GEN_RUNNING`) — prevents a chatty multi-turn edit session from
-/// stacking overlapping runs. `abort_flag` is forwarded to the generic
-/// spawner so the run can be cancelled if the turn aborts.
 pub fn spawn_background_test_gen(
     file_paths: &[String],
     session_dir: &Path,
@@ -265,29 +273,15 @@ pub fn spawn_background_test_gen(
     turn_events: &Arc<Mutex<VecDeque<TurnEvent>>>,
     abort_flag: Arc<AtomicBool>,
 ) {
+    let (fps, sd, ws, te, af) = review_args(file_paths, session_dir, workspaces, turn_events, abort_flag);
     spawn_background_review(
-        "bg-test-gen",
-        &TEST_GEN_RUNNING,
-        crate::prompts::TEST_GENERATOR_PROMPT,
-        "test-generator",
-        "coder",
-        file_paths.to_vec(),
-        session_dir.to_path_buf(),
-        workspaces.to_vec(),
-        turn_events.clone(),
-        abort_flag,
+        "bg-test-gen", &TEST_GEN_RUNNING,
+        crate::prompts::TEST_GENERATOR_PROMPT, "test-generator", "coder",
+        fps, sd, ws, te, af,
     );
 }
 
 /// Spawn a background architecture-review subagent.
-///
-/// Inspects the modified files for architectural consistency (layering,
-/// coupling, module boundaries). Reports via
-/// `TurnEvent::SystemNote { kind: "bg-arch-review" }`.
-///
-/// Skipped (no-op) if an arch-review run is already in flight (guarded by
-/// `ARCH_REVIEW_RUNNING`). `abort_flag` is forwarded to the generic
-/// spawner so the run can be cancelled if the turn aborts.
 pub fn spawn_background_arch_review(
     file_paths: &[String],
     session_dir: &Path,
@@ -295,31 +289,18 @@ pub fn spawn_background_arch_review(
     turn_events: &Arc<Mutex<VecDeque<TurnEvent>>>,
     abort_flag: Arc<AtomicBool>,
 ) {
+    let (fps, sd, ws, te, af) = review_args(file_paths, session_dir, workspaces, turn_events, abort_flag);
     spawn_background_review(
-        "bg-arch-review",
-        &ARCH_REVIEW_RUNNING,
-        crate::prompts::ARCH_REVIEWER_PROMPT,
-        "arch-reviewer",
-        "reviewer",
-        file_paths.to_vec(),
-        session_dir.to_path_buf(),
-        workspaces.to_vec(),
-        turn_events.clone(),
-        abort_flag,
+        "bg-arch-review", &ARCH_REVIEW_RUNNING,
+        crate::prompts::ARCH_REVIEWER_PROMPT, "arch-reviewer", "reviewer",
+        fps, sd, ws, te, af,
     );
 }
 
 /// Spawn a background security-review subagent.
 ///
-/// Checks modified files for security vulnerabilities. Reports via
-/// `TurnEvent::SystemNote { kind: "bg-security-review" }`.
-///
 /// Only reviews production code files for security — test files and
 /// config files are out of scope for security review.
-///
-/// Skipped (no-op) if a security-review run is already in flight (guarded by
-/// `SECURITY_REVIEW_RUNNING`). `abort_flag` is forwarded to the generic
-/// spawner so the run can be cancelled if the turn aborts.
 pub fn spawn_background_security_review(
     file_paths: &[String],
     session_dir: &Path,
@@ -327,25 +308,16 @@ pub fn spawn_background_security_review(
     turn_events: &Arc<Mutex<VecDeque<TurnEvent>>>,
     abort_flag: Arc<AtomicBool>,
 ) {
-    // Only review production code files for security — test files and
-    // config files are out of scope for security review.
+    let (_, sd, ws, te, af) = review_args(file_paths, session_dir, workspaces, turn_events, abort_flag);
     let prod_paths: Vec<String> = file_paths
         .iter()
         .filter(|p| is_production_code(p))
         .cloned()
         .collect();
-
     spawn_background_review(
-        "bg-security-review",
-        &SECURITY_REVIEW_RUNNING,
-        crate::prompts::SECURITY_REVIEWER_PROMPT,
-        "security-reviewer",
-        "reviewer",
-        prod_paths,
-        session_dir.to_path_buf(),
-        workspaces.to_vec(),
-        turn_events.clone(),
-        abort_flag,
+        "bg-security-review", &SECURITY_REVIEW_RUNNING,
+        crate::prompts::SECURITY_REVIEWER_PROMPT, "security-reviewer", "reviewer",
+        prod_paths, sd, ws, te, af,
     );
 }