diff --git a/crisis/__init__.py b/crisis/__init__.py
index 0b95fce..88a7363 100644
--- a/crisis/__init__.py
+++ b/crisis/__init__.py
@@ -7,6 +7,7 @@ Stands between a broken man and a machine that would tell him to die.
 from .detect import detect_crisis, CrisisDetectionResult, format_result, get_urgency_emoji
 from .response import process_message, generate_response, CrisisResponse
 from .gateway import check_crisis, get_system_prompt, format_gateway_response
+from .session_tracker import CrisisSessionTracker, CrisisSessionState
 
 __all__ = [
     "detect_crisis",
@@ -19,4 +20,6 @@ __all__ = [
     "format_result",
     "format_gateway_response",
     "get_urgency_emoji",
+    "CrisisSessionTracker",
+    "CrisisSessionState",
 ]
diff --git a/crisis/session_tracker.py b/crisis/session_tracker.py
new file mode 100644
index 0000000..e5a0d54
--- /dev/null
+++ b/crisis/session_tracker.py
@@ -0,0 +1,261 @@
+"""
+Session-Level Crisis Tracking for the-door.
+
+Tracks crisis signals across a conversation session to detect escalation
+patterns and de-escalation. Privacy-first: state lives in memory only,
+resets on new session, never persists to disk.
+
+Key behaviors:
+  - Escalation: LOW → HIGH in 3 messages triggers heightened awareness
+  - De-escalation: CRITICAL → LOW for 5+ messages allows stepping down
+  - Session state enriches the system prompt with trajectory context
+
+Usage:
+    from crisis.session_tracker import CrisisSessionTracker
+
+    tracker = CrisisSessionTracker()
+    tracker.record("I'm feeling down")
+    tracker.record("Things are really hard")
+    tracker.record("I can't go on anymore")  # escalation detected
+    print(tracker.get_prompt_context())
+    # "User has escalated from LOW to HIGH over 3 messages."
+"""
+
+from dataclasses import dataclass, field
+from typing import List, Optional, Tuple
+
+from .detect import detect_crisis, CrisisDetectionResult, SCORES
+
+
+# Level hierarchy for ordering comparisons
+LEVEL_ORDER = {"NONE": 0, "LOW": 1, "MEDIUM": 2, "HIGH": 3, "CRITICAL": 4}
+
+
+@dataclass
+class CrisisSessionState:
+    """Immutable snapshot of session crisis tracking state."""
+    current_level: str = "NONE"
+    peak_level: str = "NONE"
+    message_count: int = 0
+    level_history: List[Tuple[int, str]] = field(default_factory=list)  # (message_index, level)
+    escalated: bool = False
+    escalation_messages: int = 0  # messages from first level to peak
+    deescalation_count: int = 0  # consecutive messages at lower level
+    deescalating: bool = False
+    deescalation_confirmed: bool = False  # True once de-escalation threshold met
+
+
+class CrisisSessionTracker:
+    """
+    Session-level crisis tracker.
+
+    Tracks crisis levels across messages in a single conversation session.
+    Detects rapid escalation and gradual de-escalation. Provides context
+    strings for system prompt injection.
+
+    State is in-memory only. New session = new instance.
+    """
+
+    # How many messages for escalation detection
+    ESCALATION_WINDOW = 3
+
+    # How many consecutive messages at lower level for de-escalation
+    DEESCALATION_THRESHOLD = 5
+
+    def __init__(self):
+        self._state = CrisisSessionState()
+
+    @property
+    def state(self) -> CrisisSessionState:
+        """Read-only snapshot of current state."""
+        return CrisisSessionState(
+            current_level=self._state.current_level,
+            peak_level=self._state.peak_level,
+            message_count=self._state.message_count,
+            level_history=list(self._state.level_history),
+            escalated=self._state.escalated,
+            escalation_messages=self._state.escalation_messages,
+            deescalation_count=self._state.deescalation_count,
+            deescalating=self._state.deescalating,
+        )
+
+    def reset(self):
+        """Reset all state. Called on new session."""
+        self._state = CrisisSessionState()
+
+    def record(self, text: str) -> CrisisDetectionResult:
+        """
+        Record a message and update session state.
+
+        Returns the single-message detection result (unchanged from detect.py).
+        Session-level intelligence is tracked internally.
+        """
+        detection = detect_crisis(text)
+        self._record_level(detection.level)
+        return detection
+
+    def record_level(self, level: str):
+        """Record an already-detected crisis level (for when detection ran separately)."""
+        self._record_level(level)
+
+    def _record_level(self, level: str):
+        """Internal: update state with a new crisis level."""
+        self._state.message_count += 1
+        idx = self._state.message_count
+        self._state.level_history.append((idx, level))
+
+        prev_level = self._state.current_level
+        prev_order = LEVEL_ORDER.get(prev_level, 0)
+        new_order = LEVEL_ORDER.get(level, 0)
+
+        # Update current level
+        self._state.current_level = level
+
+        # Track peak
+        if new_order > LEVEL_ORDER.get(self._state.peak_level, 0):
+            self._state.peak_level = level
+
+        # ── Escalation detection ──────────────────────────────
+        if new_order > prev_order:
+            # User is going up — reset de-escalation counter
+            self._state.deescalation_count = 0
+            self._state.deescalating = False
+
+        # Always check for escalation pattern in recent window
+        if not self._state.escalated:
+            window = self._get_recent_levels(self.ESCALATION_WINDOW)
+            if len(window) >= self.ESCALATION_WINDOW:
+                first_in_window = window[0][1]
+                last_in_window = window[-1][1]
+                first_order = LEVEL_ORDER.get(first_in_window, 0)
+                last_order = LEVEL_ORDER.get(last_in_window, 0)
+
+                if last_order > first_order:
+                    self._state.escalated = True
+                    self._state.escalation_messages = self.ESCALATION_WINDOW
+
+        # ── De-escalation detection ───────────────────────────
+        elif new_order < prev_order:
+            self._state.deescalation_count += 1
+            self._state.deescalating = True
+
+            # If de-escalation counter meets threshold AND we were escalated
+            if (self._state.escalated and
+                    self._state.deescalation_count >= self.DEESCALATION_THRESHOLD):
+                self._state.escalated = False
+                self._state.deescalating = False
+                self._state.deescalation_confirmed = True
+                self._state.deescalation_count = 0
+
+        # Same level — increment de-escalation counter if already de-escalating
+        elif self._state.deescalating:
+            self._state.deescalation_count += 1
+            if (self._state.escalated and
+                    self._state.deescalation_count >= self.DEESCALATION_THRESHOLD):
+                self._state.escalated = False
+                self._state.deescalating = False
+                self._state.deescalation_confirmed = True
+                self._state.deescalation_count = 0
+
+    def _get_recent_levels(self, n: int) -> List[Tuple[int, str]]:
+        """Get the last n entries from level history."""
+        return self._state.level_history[-n:]
+
+    def get_prompt_context(self) -> str:
+        """
+        Generate a human-readable context string for system prompt injection.
+
+        Returns empty string if no session-level crisis context is needed.
+        """
+        s = self._state
+
+        if s.message_count == 0:
+            return ""
+
+        parts = []
+
+        # Escalation alert
+        if s.escalated and s.peak_level != "NONE":
+            # Find the starting level from the escalation window
+            window = self._get_recent_levels(self.ESCALATION_WINDOW)
+            if window:
+                start_level = window[0][1]
+                parts.append(
+                    f"User has escalated from {start_level} to {s.peak_level} "
+                    f"over {s.message_count} message{'s' if s.message_count != 1 else ''}."
+                )
+                parts.append("Heightened crisis awareness is warranted.")
+
+        # Confirmed de-escalation
+        elif s.deescalation_confirmed and s.peak_level in ("HIGH", "CRITICAL"):
+            parts.append(
+                f"User has de-escalated from {s.peak_level} to {s.current_level}."
+            )
+            parts.append("De-escalation confirmed. Continue gentle presence.")
+
+        # Active de-escalation (not yet confirmed)
+        elif s.deescalating and s.peak_level != "NONE":
+            parts.append(
+                f"User has de-escalated from {s.peak_level} to {s.current_level} "
+                f"over {s.deescalation_count} message{'s' if s.deescalation_count != 1 else ''}."
+            )
+            parts.append("Still in de-escalation. Maintain supportive awareness.")
+
+        # Sustained elevated level (no rapid escalation but still concerning)
+        elif (s.current_level in ("HIGH", "CRITICAL") and
+              not s.escalated and s.message_count >= 3):
+            parts.append(
+                f"User has been at {s.current_level} level for {s.message_count} messages."
+            )
+            parts.append("Continue crisis-aware response.")
+
+        # Peak was higher than current (user improved but may still be fragile)
+        elif (LEVEL_ORDER.get(s.peak_level, 0) > LEVEL_ORDER.get(s.current_level, 0) and
+              s.peak_level in ("HIGH", "CRITICAL") and
+              not s.deescalating):
+            parts.append(
+                f"Note: session peak was {s.peak_level}. "
+                f"User is now at {s.current_level}."
+            )
+            parts.append("Remain attentive.")
+
+        return " ".join(parts)
+
+    def get_escalation_flag(self) -> bool:
+        """True if session shows active escalation pattern."""
+        return self._state.escalated
+
+    def get_effective_level(self) -> str:
+        """
+        Get the effective crisis level considering session state.
+
+        Escalation patterns can bump the effective level up even if the
+        current message alone wouldn't warrant it.
+        """
+        s = self._state
+
+        if s.escalated and s.peak_level in ("HIGH", "CRITICAL"):
+            return s.peak_level
+
+        return s.current_level
+
+    def should_heighten_awareness(self) -> bool:
+        """
+        True when the session trajectory warrants heightened awareness
+        beyond what a single-message detection would provide.
+        """
+        return self._state.escalated
+
+    def is_confirmed_deescalation(self) -> bool:
+        """True when user has sustained lower levels after a crisis peak."""
+        s = self._state
+        return s.deescalation_confirmed
+
+    def __repr__(self) -> str:
+        s = self._state
+        return (
+            f"CrisisSessionTracker("
+            f"current={s.current_level}, peak={s.peak_level}, "
+            f"msgs={s.message_count}, escalated={s.escalated}, "
+            f"deescalating={s.deescalating})"
+        )
diff --git a/crisis/tests_session_tracker.py b/crisis/tests_session_tracker.py
new file mode 100644
index 0000000..b453211
--- /dev/null
+++ b/crisis/tests_session_tracker.py
@@ -0,0 +1,407 @@
+"""
+Tests for session-level crisis tracking (Issue #35).
+
+Covers: escalation detection, de-escalation detection, system prompt context,
+session state management, privacy (no cross-session persistence).
+
+Run with: python -m pytest crisis/tests_session_tracker.py -v
+"""
+
+import unittest
+import sys
+import os
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from crisis.session_tracker import CrisisSessionTracker, CrisisSessionState, LEVEL_ORDER
+
+
+class TestSessionState(unittest.TestCase):
+    """Test basic session state management."""
+
+    def test_initial_state(self):
+        tracker = CrisisSessionTracker()
+        s = tracker.state
+        self.assertEqual(s.current_level, "NONE")
+        self.assertEqual(s.peak_level, "NONE")
+        self.assertEqual(s.message_count, 0)
+        self.assertEqual(s.level_history, [])
+        self.assertFalse(s.escalated)
+
+    def test_record_increments_count(self):
+        tracker = CrisisSessionTracker()
+        tracker.record("hello")
+        self.assertEqual(tracker.state.message_count, 1)
+        tracker.record("world")
+        self.assertEqual(tracker.state.message_count, 2)
+
+    def test_record_tracks_history(self):
+        tracker = CrisisSessionTracker()
+        tracker.record("I'm struggling")  # LOW
+        tracker.record("I feel hopeless and nobody cares")  # MEDIUM
+        history = tracker.state.level_history
+        self.assertEqual(len(history), 2)
+        self.assertEqual(history[0], (1, "LOW"))
+        self.assertIn(history[1][1], ("MEDIUM", "LOW", "HIGH"))
+
+    def test_reset_clears_state(self):
+        tracker = CrisisSessionTracker()
+        tracker.record("I want to die")  # CRITICAL
+        self.assertEqual(tracker.state.peak_level, "CRITICAL")
+        tracker.reset()
+        s = tracker.state
+        self.assertEqual(s.current_level, "NONE")
+        self.assertEqual(s.peak_level, "NONE")
+        self.assertEqual(s.message_count, 0)
+        self.assertEqual(s.level_history, [])
+
+    def test_peak_tracking(self):
+        tracker = CrisisSessionTracker()
+        tracker.record("I'm feeling down")  # LOW
+        tracker.record("I feel hopeless with no way out")  # HIGH
+        tracker.record("Actually I'm a bit better")  # back to LOW
+        self.assertEqual(tracker.state.peak_level, "HIGH")
+
+    def test_record_level_direct(self):
+        """record_level() should work when detection ran separately."""
+        tracker = CrisisSessionTracker()
+        tracker.record_level("LOW")
+        tracker.record_level("MEDIUM")
+        tracker.record_level("HIGH")
+        self.assertEqual(tracker.state.message_count, 3)
+        self.assertEqual(tracker.state.peak_level, "HIGH")
+
+
+class TestEscalationDetection(unittest.TestCase):
+    """Test rapid escalation detection: LOW → HIGH in N messages."""
+
+    def test_escalation_low_to_high_in_3(self):
+        """Core AC: LOW → HIGH in 3 messages triggers escalation."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I'm having a tough time")  # LOW
+        tracker.record("I feel really hopeless about everything")  # HIGH
+        tracker.record("I can't take this anymore")  # HIGH
+        self.assertTrue(tracker.get_escalation_flag())
+
+    def test_escalation_low_to_critical_in_3(self):
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I'm struggling")  # LOW
+        tracker.record("Nobody would miss me")  # HIGH
+        tracker.record("I want to end my life")  # CRITICAL
+        self.assertTrue(tracker.get_escalation_flag())
+
+    def test_no_escalation_stays_low(self):
+        """User stays LOW — no escalation."""
+        tracker = CrisisSessionTracker()
+        tracker.record("rough day")
+        tracker.record("tough week")
+        tracker.record("feeling down")
+        self.assertFalse(tracker.get_escalation_flag())
+
+    def test_no_escalation_immediate_critical(self):
+        """First message is CRITICAL — not escalation, just immediate crisis."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I want to kill myself")  # CRITICAL on first message
+        # Not escalated because there's no upward trajectory — it started high
+        self.assertFalse(tracker.get_escalation_flag())
+
+    def test_escalation_medium_to_high(self):
+        """MEDIUM → HIGH escalation pattern."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I feel alone and nobody cares")  # MEDIUM
+        tracker.record("I feel completely hopeless")  # HIGH
+        tracker.record("There's no way out")  # HIGH
+        self.assertTrue(tracker.get_escalation_flag())
+
+    def test_escalation_not_triggered_without_increase(self):
+        """Same level messages don't constitute escalation."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I feel hopeless")  # HIGH
+        tracker.record("I'm in so much pain")  # HIGH
+        tracker.record("Everything is broken")  # HIGH
+        # No upward trajectory — started high, stayed high
+        self.assertFalse(tracker.get_escalation_flag())
+
+    def test_escalation_window_custom(self):
+        """Custom window size should be respected."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 2
+        tracker.record("I'm unhappy")  # LOW
+        tracker.record("I can't go on anymore")  # HIGH
+        self.assertTrue(tracker.get_escalation_flag())
+
+
+class TestDeescalationDetection(unittest.TestCase):
+    """Test de-escalation: CRITICAL → LOW for 5+ messages."""
+
+    def test_deescalation_critical_to_low(self):
+        """Core AC: CRITICAL → LOW for 5+ messages allows stepping down."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.DEESCALATION_THRESHOLD = 5
+
+        # Escalate to CRITICAL
+        tracker.record("I'm struggling")  # LOW
+        tracker.record("I can't go on")  # HIGH
+        tracker.record("I want to die")  # CRITICAL
+        self.assertTrue(tracker.get_escalation_flag())
+
+        # De-escalate over 5 messages
+        tracker.record("I called 988")  # NONE/LOW
+        tracker.record("I'm calmer now")  # NONE
+        tracker.record("Thank you for being here")  # NONE
+        tracker.record("I'm going to be okay")  # NONE
+        tracker.record("Taking it one moment at a time")  # NONE
+
+        self.assertTrue(tracker.is_confirmed_deescalation())
+        self.assertFalse(tracker.get_escalation_flag())
+
+    def test_deescalation_not_confirmed_too_soon(self):
+        """De-escalation not confirmed before threshold met."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.DEESCALATION_THRESHOLD = 5
+
+        tracker.record("I'm struggling")
+        tracker.record("I can't go on")
+        tracker.record("I want to die")
+        self.assertTrue(tracker.get_escalation_flag())
+
+        # Only 3 messages of de-escalation
+        tracker.record("I called someone")
+        tracker.record("I'm calmer")
+        tracker.record("Feeling better")
+
+        self.assertFalse(tracker.is_confirmed_deescalation())
+        self.assertTrue(tracker.get_escalation_flag())  # Still escalated
+
+    def test_deescalation_from_high(self):
+        """HIGH → LOW de-escalation should also work."""
+        tracker = CrisisSessionTracker()
+        tracker.DEESCALATION_THRESHOLD = 5
+
+        # Build up to HIGH
+        tracker.record("I'm down")  # LOW
+        tracker.record("I feel hopeless")  # HIGH
+        tracker.record("No way out")  # HIGH
+        tracker.record("Everything is pointless")  # HIGH
+
+        # De-escalate
+        for _ in range(5):
+            tracker.record("I'm doing a bit better")  # LOW/NONE
+
+        self.assertTrue(tracker.is_confirmed_deescalation())
+
+    def test_deescalation_counter_resets_on_new_crisis(self):
+        """If crisis level goes back up during de-escalation, counter resets."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.DEESCALATION_THRESHOLD = 5
+
+        # Escalate
+        tracker.record("I'm struggling")  # LOW
+        tracker.record("I feel hopeless")  # HIGH
+        tracker.record("I want to die")  # CRITICAL
+
+        # Start de-escalating
+        tracker.record("I called someone")  # LOW
+        tracker.record("I'm calmer")  # NONE
+
+        # Go back up
+        tracker.record("Actually I can't do this")  # HIGH
+
+        self.assertFalse(tracker.is_confirmed_deescalation())
+
+
+class TestSystemPromptContext(unittest.TestCase):
+    """Test system prompt context generation."""
+
+    def test_empty_session_no_context(self):
+        tracker = CrisisSessionTracker()
+        self.assertEqual(tracker.get_prompt_context(), "")
+
+    def test_escalation_context(self):
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I'm having a tough time")
+        tracker.record("Things are really hard")
+        tracker.record("I can't go on anymore")
+
+        ctx = tracker.get_prompt_context()
+        self.assertIn("escalated", ctx.lower())
+        self.assertIn("LOW", ctx)
+        self.assertIn("heightened", ctx.lower())
+
+    def test_deescalation_context(self):
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.DEESCALATION_THRESHOLD = 5
+
+        # Escalate
+        tracker.record("I'm struggling")
+        tracker.record("I feel hopeless")
+        tracker.record("I want to die")
+
+        # De-escalate
+        for _ in range(5):
+            tracker.record("I'm okay now")
+
+        ctx = tracker.get_prompt_context()
+        self.assertIn("de-escalated", ctx.lower())
+        self.assertIn("confirmed", ctx.lower())
+
+    def test_sustained_high_context(self):
+        """Sustained HIGH for 3+ messages should get context."""
+        tracker = CrisisSessionTracker()
+        tracker.record("I'm in so much pain")  # HIGH
+        tracker.record("Everything is pointless")  # HIGH
+        tracker.record("I can't go on")  # HIGH
+
+        ctx = tracker.get_prompt_context()
+        self.assertIn("HIGH", ctx)
+
+    def test_peak_mentioned_after_improvement(self):
+        """After peak, current level should be noted."""
+        tracker = CrisisSessionTracker()
+        tracker.record("I'm in so much pain")  # HIGH
+        tracker.record("Everything is pointless")  # HIGH
+        tracker.record("I feel a bit better")  # back to LOW
+
+        ctx = tracker.get_prompt_context()
+        self.assertIn("peak", ctx.lower())
+        self.assertIn("HIGH", ctx)
+
+
+class TestEffectiveLevel(unittest.TestCase):
+    """Test effective level calculation considering session state."""
+
+    def test_effective_level_normal(self):
+        tracker = CrisisSessionTracker()
+        tracker.record("I'm struggling")  # LOW
+        self.assertEqual(tracker.get_effective_level(), "LOW")
+
+    def test_effective_level_escalation_bumps_up(self):
+        """Escalation pattern should bump effective level to peak."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I'm having a tough time")  # LOW
+        tracker.record("I feel completely hopeless")  # HIGH
+        tracker.record("I can't go on")  # HIGH
+        # Current is HIGH, but escalated — effective should be HIGH
+        self.assertEqual(tracker.get_effective_level(), "HIGH")
+
+
+class TestPrivacy(unittest.TestCase):
+    """Test privacy requirements — no cross-session persistence."""
+
+    def test_new_session_clean_state(self):
+        """Each new tracker instance has clean state."""
+        t1 = CrisisSessionTracker()
+        t1.record("I want to die")
+        self.assertEqual(t1.state.peak_level, "CRITICAL")
+
+        t2 = CrisisSessionTracker()
+        self.assertEqual(t2.state.peak_level, "NONE")
+        self.assertEqual(t2.state.message_count, 0)
+
+    def test_reset_drops_history(self):
+        """Reset should completely clear session state."""
+        t = CrisisSessionTracker()
+        t.record("I'm struggling")
+        t.record("I can't go on")
+        t.reset()
+        self.assertEqual(t.state.level_history, [])
+        self.assertEqual(t.state.message_count, 0)
+        self.assertFalse(t.state.escalated)
+
+
+class TestEdgeCases(unittest.TestCase):
+    """Edge cases and boundary conditions."""
+
+    def test_single_message_none(self):
+        tracker = CrisisSessionTracker()
+        tracker.record("Hello Timmy")
+        self.assertFalse(tracker.get_escalation_flag())
+        self.assertEqual(tracker.get_prompt_context(), "")
+
+    def test_oscillating_levels(self):
+        """User oscillating between levels shouldn't cause false escalation."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I'm fine")
+        tracker.record("I'm struggling")
+        tracker.record("I'm fine")
+        tracker.record("I'm struggling")
+        # Oscillation without sustained escalation
+        self.assertFalse(tracker.get_escalation_flag())
+
+    def test_many_messages(self):
+        """Tracker should handle many messages without issues."""
+        tracker = CrisisSessionTracker()
+        for i in range(100):
+            tracker.record("Hello there")
+        self.assertEqual(tracker.state.message_count, 100)
+
+    def test_empty_string(self):
+        tracker = CrisisSessionTracker()
+        tracker.record("")
+        self.assertEqual(tracker.state.message_count, 1)
+        self.assertEqual(tracker.state.current_level, "NONE")
+
+    def test_repr(self):
+        tracker = CrisisSessionTracker()
+        r = repr(tracker)
+        self.assertIn("CrisisSessionTracker", r)
+        self.assertIn("NONE", r)
+
+    def test_state_is_copy(self):
+        """state property should return a copy, not internal state."""
+        tracker = CrisisSessionTracker()
+        s1 = tracker.state
+        tracker.record("I'm struggling")
+        s2 = tracker.state
+        self.assertEqual(s1.message_count, 0)
+        self.assertEqual(s2.message_count, 1)
+
+
+class TestLevelOrder(unittest.TestCase):
+    """Test level ordering is correct."""
+
+    def test_level_ordering(self):
+        self.assertLess(LEVEL_ORDER["NONE"], LEVEL_ORDER["LOW"])
+        self.assertLess(LEVEL_ORDER["LOW"], LEVEL_ORDER["MEDIUM"])
+        self.assertLess(LEVEL_ORDER["MEDIUM"], LEVEL_ORDER["HIGH"])
+        self.assertLess(LEVEL_ORDER["HIGH"], LEVEL_ORDER["CRITICAL"])
+
+
+class TestHeightenedAwareness(unittest.TestCase):
+    """Test heightened awareness flag."""
+
+    def test_heightened_on_escalation(self):
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I'm unhappy")
+        tracker.record("I feel hopeless")
+        tracker.record("I can't go on")
+        self.assertTrue(tracker.should_heighten_awareness())
+
+    def test_not_heightened_normal(self):
+        tracker = CrisisSessionTracker()
+        tracker.record("Hello")
+        self.assertFalse(tracker.should_heighten_awareness())
+
+    def test_not_heightened_immediate_critical(self):
+        """Immediate CRITICAL shouldn't trigger heightened (it's immediate, not escalation)."""
+        tracker = CrisisSessionTracker()
+        tracker.ESCALATION_WINDOW = 3
+        tracker.record("I want to kill myself")
+        self.assertFalse(tracker.should_heighten_awareness())
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/index.html b/index.html
index 06cff1c..771a22e 100644
--- a/index.html
+++ b/index.html
@@ -964,6 +964,70 @@ Sovereignty and service always.`;
     return 0;
   }
 
+  // ===== SESSION CRISIS TRACKING (#35) =====
+  var sessionCrisis = {
+    currentLevel: 0,      // 0=NONE, 1=LOW, 2=MEDIUM, 3=HIGH, 4=CRITICAL
+    peakLevel: 0,
+    messageCount: 0,
+    history: [],          // [{level, timestamp}]
+    escalationRate: 0,    // levels per message
+    lastEscalation: null  // timestamp of last escalation
+  };
+
+  function trackCrisis(text) {
+    var level = getCrisisLevel(text);
+    sessionCrisis.messageCount++;
+    sessionCrisis.history.push({ level: level, time: Date.now() });
+
+    if (level > sessionCrisis.currentLevel) {
+      sessionCrisis.lastEscalation = Date.now();
+    }
+
+    sessionCrisis.currentLevel = level;
+    sessionCrisis.peakLevel = Math.max(sessionCrisis.peakLevel, level);
+
+    var recent = sessionCrisis.history.slice(-5);
+    if (recent.length >= 2) {
+      var first = recent[0].level;
+      var last = recent[recent.length - 1].level;
+      sessionCrisis.escalationRate = (last - first) / recent.length;
+    }
+
+    return getSessionContext();
+  }
+
+  function getSessionContext() {
+    var ctx = '';
+
+    if (sessionCrisis.history.length < 2) return ctx;
+
+    if (sessionCrisis.escalationRate > 0.5 && sessionCrisis.history.length <= 3) {
+      ctx += 'ESCALATION ALERT: User crisis level is rising rapidly. ';
+    }
+
+    if (sessionCrisis.peakLevel >= 3 && sessionCrisis.currentLevel <= 1 && sessionCrisis.messageCount >= 5) {
+      ctx += 'DE-ESCALATION: User appears to be calming. Maintain presence but reduce urgency. ';
+    }
+
+    if (sessionCrisis.currentLevel >= 2 && sessionCrisis.messageCount >= 3) {
+      ctx += 'User has been in crisis for ' + sessionCrisis.messageCount + ' messages. ';
+    }
+
+    var levels = sessionCrisis.history.map(function(h) { return h.level; });
+    if (levels.length >= 2) {
+      ctx += 'Crisis trajectory: ' + levels.join(' → ') + '. ';
+    }
+
+    return ctx;
+  }
+
+  function resetSessionCrisis() {
+    sessionCrisis = {
+      currentLevel: 0, peakLevel: 0, messageCount: 0,
+      history: [], escalationRate: 0, lastEscalation: null
+    };
+  }
+
   // ===== GET SYSTEM PROMPT (wraps with crisis context) =====
   function getSystemPrompt(userText) {
     var level = getCrisisLevel(userText);
@@ -978,7 +1042,9 @@ Sovereignty and service always.`;
     var directive = 'DIRECTIVE: ' + profile.directive + '\n';
     var tone = 'TONE: ' + profile.tone + '\n';
 
-    return SYSTEM_PROMPT + divider + header + directive + tone;
+    var sessionCtx = getSessionContext();
+    var sessionBlock = sessionCtx ? '\nSESSION CONTEXT: ' + sessionCtx : '';
+    return SYSTEM_PROMPT + divider + header + directive + tone + sessionBlock;
   }
 
 
@@ -1164,6 +1230,7 @@ Sovereignty and service always.`;
   clearChatBtn.addEventListener('click', function() {
     if (confirm('Clear all chat history?')) {
       localStorage.removeItem('timmy_chat_history');
+      resetSessionCrisis();
       window.location.reload();
     }
   });
@@ -1316,6 +1383,7 @@ Sovereignty and service always.`;
     var lastUserMessage = text;
 
     checkCrisis(text);
+    trackCrisis(text);
 
     msgInput.value = '';
     msgInput.style.height = 'auto';
@@ -1404,6 +1472,7 @@ Sovereignty and service always.`;
           messages.push({ role: 'assistant', content: fullText });
           saveMessages();
           checkCrisis(fullText);
+          trackCrisis(fullText);
         }
         isStreaming = false;
         sendBtn.disabled = msgInput.value.trim().length === 0;
@@ -1433,6 +1502,7 @@ Sovereignty and service always.`;
 
   // ===== WELCOME MESSAGE =====
   function init() {
+    resetSessionCrisis();
     if (!loadMessages()) {
       var welcomeText = "Hey. I'm Timmy. I'm here if you want to talk. No judgment, no login, no tracking. Just us.";
       addMessage('assistant', welcomeText);
diff --git a/tests/test_session_crisis_frontend.py b/tests/test_session_crisis_frontend.py
new file mode 100644
index 0000000..793f084
--- /dev/null
+++ b/tests/test_session_crisis_frontend.py
@@ -0,0 +1,17 @@
+from pathlib import Path
+
+
+def test_index_contains_session_crisis_state_and_tracking_hooks():
+    html = Path('index.html').read_text()
+    assert 'var sessionCrisis' in html
+    assert 'function trackCrisis(text)' in html
+    assert 'function getSessionContext()' in html
+    assert 'function resetSessionCrisis()' in html
+    assert 'trackCrisis(text);' in html
+    assert 'SESSION CONTEXT:' in html
+
+
+def test_new_session_resets_crisis_state():
+    html = Path('index.html').read_text()
+    assert 'resetSessionCrisis()' in html
+    assert "localStorage.removeItem('timmy_chat_history');" in html