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/tests/leader_pty_e2e/campaign_leader_mode_remote_dismiss_on_model_pick.rs

@@ -77,7 +77,7 @@ async fn campaign_leader_mode_remote_dismiss_on_model_pick() {
             .unwrap_or(false)
     };
 
-    // ── Phase 1+2: nudge on a new session; a pick records the dismissal in
+    // Phase 1+2: nudge on a new session; a pick records the dismissal in
     // the TUI process. Retries fresh TUI spawns (same leader) so a missed
     // 2s prefetch window on a loaded runner can't wedge the test.
     let mut recorded = false;
@@ -116,7 +116,7 @@ async fn campaign_leader_mode_remote_dismiss_on_model_pick() {
         "leader-mode TUI must record the remote campaign dismissal in {state_path:?}"
     );
 
-    // ── Phase 3: the dismissal is durable and the pick is persisted. The
+    // Phase 3: the dismissal is durable and the pick is persisted. The
     // user's choice must be in config.toml (campaign value never laundered
     // in), and the dismissed id on disk is what every future resolution —
     // leader or not — filters on (`dismissed_id_is_dropped_from_override`

crates/codegen/kigi-tui/tests/leader_pty_e2e/common.rs

@@ -26,12 +26,9 @@ pub(crate) const PROMPT: &str = "go";
 /// Response sentinel the mock server streams back.
 pub(crate) const MOCK_RESPONSE_SENTINEL: &str = "MOCKRESPONSE";
 
-/// Cold leader-client bring-up budget. History: 60s → 120s → 240s while these
-/// cases ran interleaved with the full `pty_e2e` suite (each leader case
-/// spawns multiple full pager processes; suite-wide contention pushed cold
-/// bring-up past two minutes). Now that the leader cases run in their own
-/// serialized target the budget can come back down after a green soak week —
-/// tracked in the leader test-infra plan.
+/// Cold leader-client bring-up budget, generous because each leader case
+/// spawns multiple full pager processes; can come back down after a green
+/// soak week — tracked in the leader test-infra plan.
 pub(crate) const LEADER_TIMEOUT: Duration = Duration::from_secs(240);
 
 /// Streamed-turn deadline in leader mode (same contention rationale).

crates/codegen/kigi-tui/tests/leader_pty_e2e/leader_n_clients_shared_session.rs

@@ -28,7 +28,6 @@ async fn leader_n_clients_shared_session() {
         .content()
         .set_response(format!("{} first turn payload.", turn_sentinel(1)));
 
-    // The driver spawns the leader and runs turn 1.
     let mut a = cluster.spawn_leader(&[]).expect("spawn driver");
     a.wait_for_text(WELCOME_SCREEN_SENTINEL, LEADER_TIMEOUT)
         .expect("driver welcome");
@@ -60,7 +59,6 @@ async fn leader_n_clients_shared_session() {
         viewers.push(v);
     }
 
-    // Turn 2 driven from the driver streams live into EVERY viewer (fan-out).
     cluster
         .content()
         .set_response(format!("{} second turn payload.", turn_sentinel(2)));

crates/codegen/kigi-tui/tests/leader_pty_e2e/leader_reattach_cancellation_roundtrips_durable_log.rs

@@ -40,8 +40,7 @@ async fn leader_reattach_cancellation_roundtrips_durable_log() {
         .expect("A welcome");
     a.inject_keys(format!("{PROMPT}\r").as_bytes())
         .expect("A submit turn");
-    // Wait until the turn is clearly streaming (sentinel visible); this also
-    // closes the leader's rewind window so cancel is not confused with rewind.
+    // Also closes the leader's rewind window, so cancel is not confused with rewind.
     a.wait_for_text(&turn_sentinel(1), STREAM_TIMEOUT)
         .expect("A turn streaming");
 

crates/codegen/kigi-tui/tests/leader_pty_e2e/leader_reattach_completion_roundtrips_durable_log.rs

@@ -20,7 +20,6 @@ async fn leader_reattach_completion_roundtrips_durable_log() {
         .content()
         .set_response(format!("{} completed turn payload.", turn_sentinel(1)));
 
-    // A elects the leader and drives one turn to completion.
     let mut a = cluster.spawn_leader(&[]).expect("spawn leader client A");
     a.wait_for_text(WELCOME_SCREEN_SENTINEL, LEADER_TIMEOUT)
         .expect("A welcome");
@@ -53,8 +52,6 @@ async fn leader_reattach_completion_roundtrips_durable_log() {
     // must see no new inference request while C catches up.
     let inference_before_reattach = inference_request_count(cluster.content());
 
-    // Fresh reattach AFTER A exits: it replays the completed transcript via the
-    // durable rail through the surviving leader.
     drop(a);
     let mut c = cluster.attach(&[]).expect("spawn fresh reattach client C");
     c.wait_for_text(&turn_sentinel(1), LEADER_TIMEOUT)

crates/codegen/kigi-tui/tests/leader_pty_e2e/leader_two_clients_shared_session.rs

@@ -46,7 +46,6 @@ async fn leader_two_clients_shared_session() {
         "A's turn must appear in B exactly once (duplicated replay?)\nB screen:\n{b_screen}"
     );
 
-    // Turn 2 driven from A streams live into the attached viewer B.
     cluster
         .content()
         .set_response(format!("{} second turn payload.", turn_sentinel(2)));