From ae504bdc5afa33ec7ed3e77556674181b2f59a2b Mon Sep 17 00:00:00 2001
From: Thomas Mustier <6326440+tmustier@users.noreply.github.com>
Date: Wed, 27 May 2026 12:36:11 +0100
Subject: [PATCH] Fix Pinet Escape suppression for encoded key events

---
 slack-bridge/session-ui-runtime.test.ts | 37 ++++++++++++++++++
 slack-bridge/session-ui-runtime.ts      | 50 ++++++++++++++++++++++++-
 2 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/slack-bridge/session-ui-runtime.test.ts b/slack-bridge/session-ui-runtime.test.ts
index e576a63..38aee67 100644
--- a/slack-bridge/session-ui-runtime.test.ts
+++ b/slack-bridge/session-ui-runtime.test.ts
@@ -100,6 +100,43 @@ describe("createSessionUiRuntime", () => {
     expect(drainInbox).toHaveBeenCalledTimes(2);
   });
 
+  it.each([
+    ["raw Escape", "\u001b"],
+    ["Kitty CSI-u Escape", "\u001b[27u"],
+    ["Kitty CSI-u Escape with explicit no modifier", "\u001b[27;1u"],
+    ["Kitty CSI-u Escape release", "\u001b[27;1:3u"],
+    ["Kitty CSI-u Escape with Caps Lock", "\u001b[27;65u"],
+    ["xterm modifyOtherKeys Escape", "\u001b[27;1;27~"],
+  ])("gates idle inbox draining after %s input", (_name, data) => {
+    const { deps, drainInbox } = createDeps();
+    const runtime = createSessionUiRuntime(deps);
+    const { ctx } = createContext({ idle: true });
+
+    runtime.notePotentialInterruptInput(data);
+
+    expect(runtime.shouldSuppressAutomaticInboxDrain(Date.now())).toBe(true);
+    expect(runtime.maybeDrainInboxIfIdle(ctx)).toBe(false);
+    expect(drainInbox).not.toHaveBeenCalled();
+  });
+
+  it.each([
+    ["Alt+Escape Kitty CSI-u", "\u001b[27;3u"],
+    ["Ctrl+Escape Kitty CSI-u", "\u001b[27;5u"],
+    ["Alt+Escape modifyOtherKeys", "\u001b[27;3;27~"],
+    ["Alt+a legacy sequence", "\u001ba"],
+    ["arrow sequence", "\u001b[A"],
+  ])("does not gate inbox draining after non-plain Escape-like %s input", (_name, data) => {
+    const { deps, drainInbox } = createDeps();
+    const runtime = createSessionUiRuntime(deps);
+    const { ctx } = createContext({ idle: true });
+
+    runtime.notePotentialInterruptInput(data);
+
+    expect(runtime.shouldSuppressAutomaticInboxDrain(Date.now())).toBe(false);
+    expect(runtime.maybeDrainInboxIfIdle(ctx)).toBe(true);
+    expect(drainInbox).toHaveBeenCalledTimes(1);
+  });
+
   it("schedules an inbox drain retry until the session is truly idle", async () => {
     vi.useFakeTimers();
     try {
diff --git a/slack-bridge/session-ui-runtime.ts b/slack-bridge/session-ui-runtime.ts
index afef7e2..af6bfeb 100644
--- a/slack-bridge/session-ui-runtime.ts
+++ b/slack-bridge/session-ui-runtime.ts
@@ -2,6 +2,9 @@ import type { ExtensionContext } from "@earendil-works/pi-coding-agent";
 
 const AUTO_DRAIN_INTERRUPT_SUPPRESSION_MS = 1_500;
 const AUTO_DRAIN_IDLE_RETRY_MS = 250;
+const ESCAPE_SEQUENCE = "\u001b";
+const ESCAPE_CODEPOINT = 27;
+const KITTY_LOCK_MODIFIER_MASK = 64 + 128; // Caps Lock + Num Lock.
 
 export type SessionUiStatusState = "ok" | "reconnecting" | "error" | "off";
 
@@ -30,6 +33,51 @@ type SessionUiWithTerminalInput = ExtensionContext["ui"] & {
   ) => () => void;
 };
 
+function isUnmodifiedEscapeInput(data: string): boolean {
+  // Pi enables Kitty keyboard protocol or xterm modifyOtherKeys when available, so
+  // plain Escape may arrive as an encoded key event rather than a raw ESC byte.
+  if (data === ESCAPE_SEQUENCE) {
+    return true;
+  }
+
+  return isUnmodifiedKittyEscapeInput(data) || isUnmodifiedModifyOtherKeysEscapeInput(data);
+}
+
+function isUnmodifiedKittyEscapeInput(data: string): boolean {
+  if (!data.startsWith(`${ESCAPE_SEQUENCE}[`) || !data.endsWith("u")) {
+    return false;
+  }
+
+  const body = data.slice(2, -1);
+  const [codepointWithAlternateKeys, modifierWithEventType, ...extraParts] = body.split(";");
+  if (!codepointWithAlternateKeys || extraParts.length > 0) {
+    return false;
+  }
+
+  const codepoint = Number.parseInt(codepointWithAlternateKeys.split(":")[0] ?? "", 10);
+  const modifierValue = Number.parseInt(modifierWithEventType?.split(":")[0] ?? "1", 10);
+  return (
+    codepoint === ESCAPE_CODEPOINT &&
+    Number.isFinite(modifierValue) &&
+    ((modifierValue - 1) & ~KITTY_LOCK_MODIFIER_MASK) === 0
+  );
+}
+
+function isUnmodifiedModifyOtherKeysEscapeInput(data: string): boolean {
+  if (!data.startsWith(`${ESCAPE_SEQUENCE}[`) || !data.endsWith("~")) {
+    return false;
+  }
+
+  const body = data.slice(2, -1);
+  const [prefix, modifier, codepoint, ...extraParts] = body.split(";");
+  if (prefix !== "27" || codepoint !== "27" || extraParts.length > 0) {
+    return false;
+  }
+
+  const modifierValue = Number.parseInt(modifier ?? "", 10);
+  return Number.isFinite(modifierValue) && ((modifierValue - 1) & ~KITTY_LOCK_MODIFIER_MASK) === 0;
+}
+
 export function createSessionUiRuntime(deps: SessionUiRuntimeDeps): SessionUiRuntime {
   let suppressAutoDrainUntil = 0;
   let terminalInputUnsubscribe: (() => void) | null = null;
@@ -73,7 +121,7 @@ export function createSessionUiRuntime(deps: SessionUiRuntimeDeps): SessionUiRun
   }
 
   function notePotentialInterruptInput(data: string): void {
-    if (data !== "\u001b") {
+    if (!isUnmodifiedEscapeInput(data)) {
       return;
     }