feat(cli): double ESC discards the draft, even mid-stream

Ctrl+C interrupts a running turn and only clears the composer when idle,
so there was no way to discard a half-typed prompt while the agent was
streaming. Claude Code and Gemini CLI both bind that to double-Esc.

Appends the draft to history before clearing, so Up recalls it — the same
undo affordance Claude Code gives, which is what makes this safe on a key
people hit by reflex. Excluded when a modal prompt is up, since those bind
ESC eagerly and cancel should still win.

Co-authored-by: Brooklyn Nicholson <brooklyn.bb.nicholson@gmail.com>

cli.py

@@ -15592,6 +15592,32 @@ class HermesCLI(CLIAgentSetupMixin, CLICommandsMixin, CLIBillingMixin):
                 event.app.invalidate()
                 return
 
+        @kb.add('escape', 'escape', filter=~_modal_prompt_active)
+        def handle_double_escape(event):
+            """Double ESC: discard the current draft and any attached images.
+
+            Matches Claude Code / Gemini CLI, where double-Esc is the
+            clear-the-composer gesture. It works while the agent is
+            streaming, which is the gap Ctrl+C leaves: Ctrl+C interrupts a
+            running turn and only clears the draft when idle, so mid-stream
+            there was no way to discard a half-typed prompt.
+
+            The draft is appended to history first, so Up recalls it — the
+            same undo affordance Claude Code provides, and the reason this
+            is safe to bind to a key pressed by reflex.
+
+            Single ESC is the prefix for Alt sequences (escape+enter,
+            escape+g, escape+v), so prompt_toolkit's escape-timeout keeps
+            those distinct from the double press. Modal prompts bind ESC
+            eagerly and are excluded here so cancel still wins.
+            """
+            buf = event.app.current_buffer
+            if not (buf.text or cli_ref._attached_images):
+                return
+            buf.reset(append_to_history=bool(buf.text))
+            cli_ref._attached_images.clear()
+            event.app.invalidate()
+
         @kb.add('c-z')
         def handle_ctrl_z(event):
             """Handle Ctrl+Z - suspend process to background (Unix only)."""