docs(comments): rewrite comments across all crates to the guidelines

Sweep every first-party crate source (1956 .rs files) to the project comment
guidelines: delete redundant restatements, decorative banners, change
narration, and end-of-line comments; keep and tighten the crucial ones
(invariants, bug rationale, SAFETY blocks, ported-source attribution).

No functional code changed. Every edit is proven comment-only against the
prior tree by a comment-stripping lexer (string/char/raw-string aware) plus a
separate doctest-fence check. Where removing a comment made rustfmt or clippy
want to re-lay-out adjacent code, the minimal triggering comment is restored so
code tokens stay byte-identical.

Gates green: cargo fmt --all --check (0 diffs), cargo check and cargo clippy
--workspace --all-targets (0 warnings).

Adds scripts/check_codegen_comment_guidelines.py — the enforcement gate for
these guidelines (flags banners, end-of-line comments, change narration, and
commented-out code).

crates/codegen/kigi-tui/src/slash/commands/copy.rs

@@ -153,7 +153,6 @@ mod tests {
 
     #[test]
     fn not_available_in_minimal() {
-        // Native terminal selection replaces the in-app copy path in minimal.
         assert!(!CopyCommand.available_in_minimal());
     }
 }

crates/codegen/kigi-tui/src/slash/commands/dashboard.rs

@@ -140,7 +140,6 @@ mod tests {
 
     #[test]
     fn not_available_in_minimal() {
-        // The dashboard is out of scope in scrollback-native minimal mode.
         assert!(!DashboardCommand.available_in_minimal());
     }
 }

crates/codegen/kigi-tui/src/slash/commands/export.rs

@@ -106,7 +106,6 @@ fn list_path_completions(cwd: &Path, query: &str) -> Vec<ArgItem> {
         (parent.to_path_buf(), prefix.to_string())
     };
 
-    // Resolve relative paths against cwd.
     let resolved = if dir_to_list.is_relative() {
         cwd.join(&dir_to_list)
     } else {
@@ -148,7 +147,7 @@ fn list_path_completions(cwd: &Path, query: &str) -> Vec<ArgItem> {
         }
     }
 
-    // Sort: directories first, then alphabetical. Truncate after sort.
+    // Directories first, then alphabetical.
     items.sort_by(|a, b| {
         let a_dir = a.display.ends_with('/');
         let b_dir = b.display.ends_with('/');

crates/codegen/kigi-tui/src/slash/commands/fork.rs

@@ -140,8 +140,6 @@ mod tests {
     use super::*;
     use crate::acp::model_state::ModelState;
 
-    // -- parse_fork_args ---------------------------------------------------
-
     #[test]
     fn parse_empty_returns_none_directive_and_no_override() {
         let parsed = parse_fork_args("").expect("empty args parse");
@@ -255,8 +253,6 @@ mod tests {
         assert_eq!(parsed.directive.as_deref(), Some("investigate"));
     }
 
-    // -- ForkCommand SlashCommand impl ------------------------------------
-
     fn make_ctx(models: &ModelState) -> CommandExecCtx<'_> {
         let bundle = Box::leak(Box::new(crate::app::bundle::BundleState::default()));
         CommandExecCtx {

crates/codegen/kigi-tui/src/slash/commands/gboom.rs

@@ -17,7 +17,6 @@ impl SlashCommand for GboomCommand {
     }
 
     fn description(&self) -> &str {
-        // Never shown: the command is hidden from the dropdown.
         "Hidden easter egg"
     }
 
@@ -25,7 +24,6 @@ impl SlashCommand for GboomCommand {
         "/gboom"
     }
 
-    /// Easter egg: typeable, never listed.
     fn visible(&self, _ctx: &AppCtx) -> bool {
         false
     }

crates/codegen/kigi-tui/src/slash/commands/home.rs

@@ -3,7 +3,6 @@
 use crate::app::actions::Action;
 use crate::slash::command::{CommandExecCtx, CommandResult, SlashCommand};
 
-/// Exit the current session and return to the welcome screen.
 pub struct HomeCommand;
 
 impl SlashCommand for HomeCommand {

crates/codegen/kigi-tui/src/slash/commands/import_claude.rs

@@ -10,7 +10,6 @@
 use crate::app::actions::Action;
 use crate::slash::command::{CommandExecCtx, CommandResult, SlashCommand};
 
-/// Open the interactive Claude settings import modal in the active session.
 pub struct ImportClaudeCommand;
 
 impl SlashCommand for ImportClaudeCommand {

crates/codegen/kigi-tui/src/slash/commands/jump.rs

@@ -68,7 +68,6 @@ mod tests {
 
     #[test]
     fn not_available_in_minimal() {
-        // Native terminal scrollback replaces in-app scrolling in minimal.
         assert!(!JumpCommand.available_in_minimal());
     }
 }

crates/codegen/kigi-tui/src/slash/commands/loop_cmd.rs

@@ -211,14 +211,22 @@ mod tests {
         // suffix, and zero-valued tokens. Each must fall through to the model
         // with no host-side cadence.
         for input in [
-            "5x do x",                    // bad suffix
-            "5 do x",                     // no suffix
-            "m do x",                     // too short / no digits
-            "55mm do x",                  // multi-char suffix
-            "0m do x",                    // zero value (tool would reject)
-            "0s do x",                    // zero value
-            "abc do x",                   // alphabetic
-            "99999999999999999999m do x", // overflows u64 -> parse Err branch
+            // bad suffix
+            "5x do x",
+            // no suffix
+            "5 do x",
+            // too short / no digits
+            "m do x",
+            // multi-char suffix
+            "55mm do x",
+            // zero value (tool would reject)
+            "0m do x",
+            // zero value
+            "0s do x",
+            // alphabetic
+            "abc do x",
+            // overflows u64 -> parse Err branch
+            "99999999999999999999m do x",
         ] {
             let (interval, prompt) = parse_loop_args(input);
             assert_eq!(interval, None, "input {input:?} must not yield a token");
@@ -228,7 +236,7 @@ mod tests {
 
     #[test]
     fn natural_language_intervals_are_not_defaulted_host_side() {
-        // The host no longer parses natural-language intervals or substitutes a
+        // The host does not parse natural-language intervals or substitute a
         // default — these all fall through to the model with no interval token.
         for input in [
             "every 30 minutes do x",

crates/codegen/kigi-tui/src/slash/commands/mod.rs

@@ -135,7 +135,6 @@ mod tests {
     use crate::slash::command::{CommandExecCtx, CommandResult};
     use crate::slash::registry::CommandRegistry;
     use agent_client_protocol as acp;
-    /// Build a ModelState with two models for testing.
     fn sample_models() -> ModelState {
         let mut models = ModelState::default();
         let id_fast = acp::ModelId::new(Arc::from("kigi-4.5"));

crates/codegen/kigi-tui/src/slash/commands/model.rs

@@ -420,8 +420,8 @@ mod tests {
 
     #[test]
     fn run_rejects_unoffered_effort_with_effort_error_not_unknown_model() {
-        // Regression: previously `resolve_effort_token_for` returned None and
-        // the handler fell through to `Unknown model: Reasoning X none`.
+        // Guards against a rejected effort token falling through to
+        // `Unknown model: Reasoning X none` instead of an effort error.
         let mut state = ModelState::default();
         let (id, info) = model_with_reasoning("reasoning-x", "Reasoning X");
         state.available.insert(id, info);

crates/codegen/kigi-tui/src/slash/commands/session_info.rs

@@ -24,7 +24,6 @@ impl SlashCommand for SessionInfoCommand {
     }
 
     fn run(&self, ctx: &mut CommandExecCtx, _args: &str) -> CommandResult {
-        // Check if we have an active session
         if ctx.session_id.is_none() {
             return CommandResult::Error("No active session".to_string());
         }

crates/codegen/kigi-tui/src/slash/commands/tasks.rs

@@ -9,7 +9,6 @@
 use crate::app::actions::Action;
 use crate::slash::command::{CommandExecCtx, CommandResult, SlashCommand};
 
-/// List background tasks, subagents, and scheduled tasks.
 pub struct TasksCommand;
 
 impl SlashCommand for TasksCommand {

crates/codegen/kigi-tui/src/slash/commands/terminal_setup.rs

@@ -64,7 +64,6 @@ impl SlashCommand for TerminalSetupCommand {
 
         let mut out = String::new();
 
-        // -- Environment --
         out.push_str("Environment\n");
         out.push_str(&format!("  terminal     {}\n", ctx.brand));
         if let Some(v) = crate::terminal::xtversion::detected() {
@@ -122,7 +121,6 @@ impl SlashCommand for TerminalSetupCommand {
             out.push_str(&format!("  newline      Alt+Enter ({detail})\n"));
         }
 
-        // -- Clipboard --
         out.push_str("\nClipboard routes\n");
         out.push_str(&format!(
             "  native       {}  (tool: {})\n",
@@ -142,7 +140,6 @@ impl SlashCommand for TerminalSetupCommand {
             crate::clipboard::wayland_data_control_label()
         ));
 
-        // -- Diagnostics --
         if warnings.is_empty() {
             out.push_str("\nNo issues found.\n");
         } else {

crates/codegen/kigi-tui/src/slash/commands/theme.rs

@@ -168,8 +168,6 @@ mod tests {
         assert!(!ThemeCommand.available_in_minimal());
     }
 
-    // -- suggest_args ---------------------------------------------------------
-
     #[test]
     fn suggest_args_prepends_auto_option() {
         with_test_env(|| {
@@ -277,8 +275,6 @@ mod tests {
         });
     }
 
-    // -- run (dispatches Action::SetTheme) ------------------------------------
-
     /// `/theme <name>` returns `Action::SetTheme(<canonical>)` —
     /// the dispatcher handles in-memory state + disk write + toast.
     #[test]
@@ -408,8 +404,6 @@ mod tests {
         });
     }
 
-    // -- preview_arg ----------------------------------------------------------
-
     #[test]
     fn preview_auto_applies_resolved_theme() {
         with_test_env(|| {
@@ -447,9 +441,7 @@ mod tests {
         });
     }
 
-    // -- cancel_preview -------------------------------------------------------
-
-    /// `cancel_preview` restores the previously-applied theme.
+    /// `cancel_preview` restores the theme that was applied before the preview.
     #[test]
     fn cancel_preview_restores_previous_kind() {
         with_test_env(|| {
@@ -484,8 +476,6 @@ mod tests {
         });
     }
 
-    // -- error handling -------------------------------------------------------
-
     #[test]
     fn run_unknown_lists_auto_in_available() {
         with_test_env(|| {