fix(gateway): plain text while busy interrupts by default again (#40590)

* fix: respect disabled auto-compaction on context overflow

Port from anomalyco/opencode#30749.

When compression.enabled is false, NO automatic compaction trigger may
fire. The proactive token-threshold paths (preflight + post-response
should_compress gate) already honoured the setting, but the three
provider-overflow recovery paths in the agent loop — long-context-tier
429, 413 payload-too-large, and context-overflow — called
_compress_context() unconditionally, silently compressing and rotating
the session against the user's explicit choice.

Add a single guard at the top of the overflow-recovery dispatch: when
compression is disabled and the error is one of those three overflow
classes, surface a terminal error (compaction_disabled: True) telling the
user to /compress manually, /new, switch to a larger-context model, or
reduce attachments. Manual /compress (force=True) is unaffected — it never
enters this loop.

Tests: new TestOverflowWithCompactionDisabled (413 + 400 overflow don't
compress when disabled; control case still compresses when enabled).
Existing overflow-recovery tests updated to enable compaction explicitly
(they verify the recovery fires); fixture defaults flipped to True to
match production (compression.enabled defaults to True).

* fix(gateway): plain text while busy interrupts by default again

busy_input_mode (default 'interrupt') was advertised as the busy-behavior
knob, but a second knob added in 7abd62719 — busy_text_mode, defaulting to
'queue' — short-circuited every plain TEXT message before busy_input_mode
was consulted. Result: plain follow-ups silently queued instead of
interrupting, even with busy_input_mode left at its 'interrupt' default
(regression #38390, silent-queue #31588).

Collapse to one source of truth: busy_input_mode drives text handling.
busy_text_mode is kept only as a legacy explicit override for back-compat
(existing queue setups keep working); when unset it follows busy_input_mode.
All default fallbacks flipped queue->interrupt. The debounce mechanism is
preserved and now keyed off the resolved mode.

Fixes #38390, #31588.

tests/gateway/test_active_session_text_merge.py

@@ -352,14 +352,15 @@ async def test_single_followup_is_stored_as_is():
     assert not adapter._active_sessions[session_key].is_set()
 
 
-def test_adapter_defaults_to_queue_mode(monkeypatch):
+def test_adapter_defaults_to_interrupt_mode(monkeypatch):
     monkeypatch.delenv("HERMES_GATEWAY_BUSY_TEXT_MODE", raising=False)
     adapter = _make_initialized_adapter()
-    assert adapter._busy_text_mode == "queue"
-    assert adapter._is_queue_text_debounce_candidate(_make_event("hello"))
+    assert adapter._busy_text_mode == "interrupt"
+    assert not adapter._is_queue_text_debounce_candidate(_make_event("hello"))
 
 
-def test_adapter_is_queue_text_debounce_candidate_by_default():
+def test_adapter_is_queue_text_debounce_candidate_when_queue_set():
+    # _make_adapter() pins _busy_text_mode="queue" to exercise debounce.
     adapter = _make_adapter()
     assert adapter._is_queue_text_debounce_candidate(_make_event("hello world"))
 

tests/gateway/test_restart_drain.py

@@ -116,22 +116,37 @@ def test_load_busy_input_mode_prefers_env_then_config_then_default(tmp_path, mon
     assert gateway_run.GatewayRunner._load_busy_input_mode() == "interrupt"
 
 
-def test_load_busy_text_mode_defaults_to_queue_and_allows_interrupt(tmp_path, monkeypatch):
+def test_load_busy_text_mode_follows_input_mode_and_honors_legacy(tmp_path, monkeypatch):
     monkeypatch.setattr(gateway_run, "_hermes_home", tmp_path)
     monkeypatch.delenv("HERMES_GATEWAY_BUSY_TEXT_MODE", raising=False)
+    monkeypatch.delenv("HERMES_GATEWAY_BUSY_INPUT_MODE", raising=False)
 
-    assert gateway_run.GatewayRunner._load_busy_text_mode() == "queue"
-
-    (tmp_path / "config.yaml").write_text(
-        "display:\n  busy_text_mode: interrupt\n", encoding="utf-8"
-    )
+    # No knobs set → follows busy_input_mode, which defaults to interrupt.
     assert gateway_run.GatewayRunner._load_busy_text_mode() == "interrupt"
 
+    # busy_input_mode=queue propagates to text handling (single source of truth).
+    (tmp_path / "config.yaml").write_text(
+        "display:\n  busy_input_mode: queue\n", encoding="utf-8"
+    )
+    assert gateway_run.GatewayRunner._load_busy_text_mode() == "queue"
+
+    # Legacy explicit busy_text_mode still wins for backward compat.
+    (tmp_path / "config.yaml").write_text(
+        "display:\n  busy_input_mode: interrupt\n  busy_text_mode: queue\n",
+        encoding="utf-8",
+    )
+    assert gateway_run.GatewayRunner._load_busy_text_mode() == "queue"
+
+    # Legacy env override wins too.
+    (tmp_path / "config.yaml").write_text(
+        "display:\n  busy_input_mode: interrupt\n", encoding="utf-8"
+    )
     monkeypatch.setenv("HERMES_GATEWAY_BUSY_TEXT_MODE", "queue")
     assert gateway_run.GatewayRunner._load_busy_text_mode() == "queue"
 
+    # Bogus legacy value is ignored → falls through to busy_input_mode (interrupt).
     monkeypatch.setenv("HERMES_GATEWAY_BUSY_TEXT_MODE", "bogus")
-    assert gateway_run.GatewayRunner._load_busy_text_mode() == "queue"
+    assert gateway_run.GatewayRunner._load_busy_text_mode() == "interrupt"
 
 
 def test_load_restart_drain_timeout_prefers_env_then_config_then_default(