feat: context pressure warnings for CLI and gateway (#2159)

* feat: context pressure warnings for CLI and gateway

User-facing notifications as context approaches the compaction threshold.
Warnings fire at 60% and 85% of the way to compaction — relative to
the configured compression threshold, not the raw context window.

CLI: Formatted line with a progress bar showing distance to compaction.
Cyan at 60% (approaching), bold yellow at 85% (imminent).

  ◐ context ▰▰▰▰▰▰▰▰▰▰▰▰▱▱▱▱▱▱▱▱ 60% to compaction  100k threshold (50%) · approaching compaction
  ⚠ context ▰▰▰▰▰▰▰▰▰▰▰▰▰▰▰▰▰▱▱▱ 85% to compaction  100k threshold (50%) · compaction imminent

Gateway: Plain-text notification sent to the user's chat via the new
status_callback mechanism (asyncio.run_coroutine_threadsafe bridge,
same pattern as step_callback).

Does NOT inject into the message stream. The LLM never sees these
warnings. Flags reset after each compaction cycle.

Files changed:
- agent/display.py — format_context_pressure(), format_context_pressure_gateway()
- run_agent.py — status_callback param, _context_50/70_warned flags,
  _emit_context_pressure(), flag reset in _compress_context()
- gateway/run.py — _status_callback_sync bridge, wired to AIAgent
- tests/test_context_pressure.py — 23 tests

* Merge remote-tracking branch 'origin/main' into hermes/hermes-7ea545bf

---------

Co-authored-by: Test <test@test.com>

agent/display.py

@@ -612,3 +612,95 @@ def write_tty(text: str) -> None:
     except OSError:
         sys.stdout.write(text)
         sys.stdout.flush()
+
+
+# =========================================================================
+# Context pressure display (CLI user-facing warnings)
+# =========================================================================
+
+# ANSI color codes for context pressure tiers
+_CYAN = "\033[36m"
+_YELLOW = "\033[33m"
+_BOLD = "\033[1m"
+_DIM_ANSI = "\033[2m"
+
+# Bar characters
+_BAR_FILLED = "▰"
+_BAR_EMPTY = "▱"
+_BAR_WIDTH = 20
+
+
+def format_context_pressure(
+    compaction_progress: float,
+    threshold_tokens: int,
+    threshold_percent: float,
+    compression_enabled: bool = True,
+) -> str:
+    """Build a formatted context pressure line for CLI display.
+
+    The bar and percentage show progress toward the compaction threshold,
+    NOT the raw context window.  100% = compaction fires.
+
+    Uses ANSI colors:
+      - cyan at ~60% to compaction = informational
+      - bold yellow at ~85% to compaction = warning
+
+    Args:
+        compaction_progress: How close to compaction (0.0–1.0, 1.0 = fires).
+        threshold_tokens: Compaction threshold in tokens.
+        threshold_percent: Compaction threshold as a fraction of context window.
+        compression_enabled: Whether auto-compression is active.
+    """
+    pct_int = int(compaction_progress * 100)
+    filled = min(int(compaction_progress * _BAR_WIDTH), _BAR_WIDTH)
+    bar = _BAR_FILLED * filled + _BAR_EMPTY * (_BAR_WIDTH - filled)
+
+    threshold_k = f"{threshold_tokens // 1000}k" if threshold_tokens >= 1000 else str(threshold_tokens)
+    threshold_pct_int = int(threshold_percent * 100)
+
+    # Tier styling
+    if compaction_progress >= 0.85:
+        color = f"{_BOLD}{_YELLOW}"
+        icon = "⚠"
+        if compression_enabled:
+            hint = "compaction imminent"
+        else:
+            hint = "no auto-compaction"
+    else:
+        color = _CYAN
+        icon = "◐"
+        hint = "approaching compaction"
+
+    return (
+        f"  {color}{icon} context {bar} {pct_int}% to compaction{_ANSI_RESET}"
+        f"  {_DIM_ANSI}{threshold_k} threshold ({threshold_pct_int}%) · {hint}{_ANSI_RESET}"
+    )
+
+
+def format_context_pressure_gateway(
+    compaction_progress: float,
+    threshold_percent: float,
+    compression_enabled: bool = True,
+) -> str:
+    """Build a plain-text context pressure notification for messaging platforms.
+
+    No ANSI — just Unicode and plain text suitable for Telegram/Discord/etc.
+    The percentage shows progress toward the compaction threshold.
+    """
+    pct_int = int(compaction_progress * 100)
+    filled = min(int(compaction_progress * _BAR_WIDTH), _BAR_WIDTH)
+    bar = _BAR_FILLED * filled + _BAR_EMPTY * (_BAR_WIDTH - filled)
+
+    threshold_pct_int = int(threshold_percent * 100)
+
+    if compaction_progress >= 0.85:
+        icon = "⚠️"
+        if compression_enabled:
+            hint = f"Context compaction is imminent (threshold: {threshold_pct_int}% of window)."
+        else:
+            hint = "Auto-compaction is disabled — context may be truncated."
+    else:
+        icon = "ℹ️"
+        hint = f"Compaction threshold is at {threshold_pct_int}% of context window."
+
+    return f"{icon} Context: {bar} {pct_int}% to compaction\n{hint}"