diff --git a/src/mudlib/commands/edit.py b/src/mudlib/commands/edit.py
index e9bd2e9..43b5937 100644
--- a/src/mudlib/commands/edit.py
+++ b/src/mudlib/commands/edit.py
@@ -60,7 +60,7 @@ async def cmd_edit(player: Player, args: str) -> None:
     player.editor = Editor(
         save_callback=save_callback_fn,
         content_type=content_type,
-        color_depth=player.color_depth,
+        color_depth=player.color_depth or "16",
         initial_content=initial_content,
     )
     player.mode_stack.append("editor")
diff --git a/src/mudlib/commands/look.py b/src/mudlib/commands/look.py
index e0904f8..0f567e5 100644
--- a/src/mudlib/commands/look.py
+++ b/src/mudlib/commands/look.py
@@ -93,10 +93,10 @@ async def cmd_look(player: Player, args: str) -> None:
         for x, tile in enumerate(row):
             # Check if this is the player's position
             if x == center_x and y == center_y:
-                line.append(colorize_terrain("@", player.color_depth))
+                line.append(colorize_terrain("@", player.color_depth or "16"))
             # Check if this is another entity's position
             elif (x, y) in entity_positions:
-                line.append(colorize_terrain("*", player.color_depth))
+                line.append(colorize_terrain("*", player.color_depth or "16"))
             else:
                 # Check for active effects at this world position
                 world_x, world_y = zone.wrap(
@@ -109,7 +109,7 @@ async def cmd_look(player: Player, args: str) -> None:
                     e = effects[-1]
                     line.append(f"{e.color}{e.char}{RESET}")
                 else:
-                    line.append(colorize_terrain(tile, player.color_depth))
+                    line.append(colorize_terrain(tile, player.color_depth or "16"))
         output_lines.append("".join(line))
 
     # Build structured output
diff --git a/src/mudlib/player.py b/src/mudlib/player.py
index 6c242a3..775dbf5 100644
--- a/src/mudlib/player.py
+++ b/src/mudlib/player.py
@@ -30,6 +30,7 @@ class Player(Entity):
     paint_mode: bool = False
     painting: bool = False
     paint_brush: str = "."
+    prompt_template: str | None = None
     _last_msdp: dict = field(default_factory=dict, repr=False)
 
     @property
@@ -38,8 +39,10 @@ class Player(Entity):
         return self.mode_stack[-1]
 
     @property
-    def color_depth(self) -> str:
-        """Best available color mode: truecolor, 256, or 16."""
+    def color_depth(self) -> str | None:
+        """Best available color mode: truecolor, 256, 16, or None if no ANSI."""
+        if not self.caps.ansi:
+            return None
         return self.caps.color_depth
 
     async def send(self, message: str) -> None:
diff --git a/src/mudlib/prompt.py b/src/mudlib/prompt.py
new file mode 100644
index 0000000..21f9bbe
--- /dev/null
+++ b/src/mudlib/prompt.py
@@ -0,0 +1,113 @@
+"""Pure functions for prompt rendering."""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from mudlib.render.colors import colorize
+
+if TYPE_CHECKING:
+    from mudlib.player import Player
+
+# Default prompt templates by mode
+DEFAULT_TEMPLATES: dict[str, str] = {
+    "normal": "{stamina_gauge} {pl} > ",
+    "combat": "{stamina_gauge} {pl} vs {opponent} > ",
+    "editor": "editor> ",
+    "if": "> ",
+}
+
+
+def render_prompt(player: Player) -> str:
+    """Render the prompt string based on player state and mode.
+
+    Args:
+        player: The player whose prompt to render
+
+    Returns:
+        Formatted prompt string with ANSI codes based on player color support
+    """
+    # Get template from player override or mode default
+    template = player.prompt_template or DEFAULT_TEMPLATES.get(
+        player.mode, "{stamina_gauge} {pl} > "
+    )
+
+    # Build variable dictionary
+    stamina_pct = (
+        int((player.stamina / player.max_stamina) * 100)
+        if player.max_stamina > 0
+        else 0
+    )
+
+    # Compute stamina gauge with conditional coloring
+    if stamina_pct >= 60:
+        stamina_gauge = f"{{green}}<{stamina_pct}%>{{/}}"
+    elif stamina_pct >= 30:
+        stamina_gauge = f"{{yellow}}<{stamina_pct}%>{{/}}"
+    else:
+        stamina_gauge = f"{{red}}<{stamina_pct}%>{{/}}"
+
+    variables = {
+        "stamina_pct": str(stamina_pct),
+        "stamina": str(round(player.stamina)),
+        "max_stamina": str(round(player.max_stamina)),
+        "stamina_gauge": stamina_gauge,
+        "pl": str(round(player.pl)),
+        "max_pl": str(round(player.max_pl)),
+        "opponent": _get_opponent_name(player),
+        "move": "",  # TODO: current attack/defense move name
+        "name": player.name,
+        "mode": player.mode,
+        "x": str(player.x),
+        "y": str(player.y),
+        "combat_state": _get_combat_state(player),
+    }
+
+    # Substitute variables in template
+    result = template
+    for key, value in variables.items():
+        result = result.replace(f"{{{key}}}", value)
+
+    # Process color tags based on player's color support
+    result = colorize(result, player.color_depth)
+
+    return result
+
+
+def _get_opponent_name(player: Player) -> str:
+    """Get the name of the player's combat opponent if any.
+
+    Args:
+        player: The player to check
+
+    Returns:
+        Opponent name if in combat, empty string otherwise
+    """
+    from mudlib.combat.engine import get_encounter
+
+    encounter = get_encounter(player)
+    if encounter is None:
+        return ""
+
+    # Determine who the opponent is (the other entity in the encounter)
+    if encounter.attacker is player:
+        return encounter.defender.name
+    return encounter.attacker.name
+
+
+def _get_combat_state(player: Player) -> str:
+    """Get the current combat state for the player.
+
+    Args:
+        player: The player to check
+
+    Returns:
+        Combat state string: "idle", "telegraph", "window", or "resolve"
+    """
+    from mudlib.combat.engine import get_encounter
+
+    encounter = get_encounter(player)
+    if encounter is None:
+        return "idle"
+
+    return encounter.state.value
diff --git a/tests/test_prompt.py b/tests/test_prompt.py
new file mode 100644
index 0000000..4ef4efe
--- /dev/null
+++ b/tests/test_prompt.py
@@ -0,0 +1,381 @@
+"""Tests for prompt rendering system."""
+
+from mudlib.caps import ClientCaps
+from mudlib.combat.encounter import CombatEncounter
+from mudlib.combat.engine import active_encounters
+from mudlib.entity import Entity
+from mudlib.player import Player
+from mudlib.prompt import render_prompt
+
+
+def setup_function():
+    """Clear global state before each test."""
+    active_encounters.clear()
+
+
+def teardown_function():
+    """Clear global state after each test."""
+    active_encounters.clear()
+
+
+def test_normal_mode_prompt():
+    """Normal mode shows stamina gauge and power level."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # 50% is in 30-59% range, should be yellow
+    assert result == "\033[33m<50%>\033[0m 200 > "
+
+
+def test_combat_mode_with_opponent():
+    """Combat mode includes opponent name."""
+    player = Player(
+        name="Goku",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal", "combat"],
+    )
+    opponent = Entity(name="Vegeta", pl=150.0)
+
+    encounter = CombatEncounter(attacker=player, defender=opponent)
+    active_encounters.append(encounter)
+
+    result = render_prompt(player)
+    # 50% is in 30-59% range, should be yellow
+    assert result == "\033[33m<50%>\033[0m 200 vs Vegeta > "
+
+
+def test_combat_mode_as_defender():
+    """Combat mode works when player is the defender."""
+    player = Player(
+        name="Goku",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal", "combat"],
+    )
+    opponent = Entity(name="Vegeta", pl=150.0)
+
+    encounter = CombatEncounter(attacker=opponent, defender=player)
+    active_encounters.append(encounter)
+
+    result = render_prompt(player)
+    # 50% is in 30-59% range, should be yellow
+    assert result == "\033[33m<50%>\033[0m 200 vs Vegeta > "
+
+
+def test_editor_mode_static_prompt():
+    """Editor mode returns static prompt."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal", "editor"],
+    )
+    result = render_prompt(player)
+    assert result == "editor> "
+
+
+def test_if_mode_static_prompt():
+    """IF mode returns minimal static prompt."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal", "if"],
+    )
+    result = render_prompt(player)
+    assert result == "> "
+
+
+def test_zero_stamina():
+    """Zero stamina renders as 0% in red."""
+    player = Player(
+        name="Test",
+        stamina=0.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # 0% is < 30%, should be red
+    assert result == "\033[31m<0%>\033[0m 200 > "
+
+
+def test_max_stamina():
+    """Full stamina renders as 100% in green."""
+    player = Player(
+        name="Test",
+        stamina=100.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # 100% is >= 60%, should be green
+    assert result == "\033[32m<100%>\033[0m 200 > "
+
+
+def test_fractional_percentage():
+    """Stamina percentage rounds to integer."""
+    player = Player(
+        name="Test",
+        stamina=33.3,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # 33% is in 30-59% range, should be yellow
+    assert result == "\033[33m<33%>\033[0m 200 > "
+
+
+def test_fractional_pl():
+    """Power level rounds to integer."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=199.7,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # 50% is in 30-59% range, should be yellow
+    assert result == "\033[33m<50%>\033[0m 200 > "
+
+
+def test_custom_template_overrides_default():
+    """Player can set custom prompt template."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+        prompt_template="[{pl}] > ",
+    )
+    result = render_prompt(player)
+    assert result == "[200] > "
+
+
+def test_custom_template_all_variables():
+    """Custom template can use all supported variables."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        max_pl=250.0,
+        mode_stack=["normal"],
+        prompt_template="{stamina}/{stamina_pct}% {pl}/{max_pl} > ",
+    )
+    result = render_prompt(player)
+    # No color tags in this custom template, so no ANSI codes
+    assert result == "50/50% 200/250 > "
+
+
+def test_unknown_variable_left_as_is():
+    """Unknown variables in template are not substituted."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+        prompt_template="{pl} {unknown} > ",
+    )
+    result = render_prompt(player)
+    assert result == "200 {unknown} > "
+
+
+def test_opponent_var_in_normal_mode_empty():
+    """Opponent variable is empty string when not in combat."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+        prompt_template="{pl} vs {opponent} > ",
+    )
+    result = render_prompt(player)
+    assert result == "200 vs  > "
+
+
+def test_no_color_support():
+    """Players with no ANSI support get tags stripped."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+        caps=ClientCaps(ansi=False),
+    )
+    result = render_prompt(player)
+    # Should have no ANSI codes, just text
+    assert result == "<50%> 200 > "
+    assert "\033[" not in result
+
+
+def test_stamina_gauge_green():
+    """Stamina >= 60% renders green gauge."""
+    player = Player(
+        name="Test",
+        stamina=80.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # Should have green color code
+    assert "\033[32m<80%>\033[0m" in result
+
+
+def test_stamina_gauge_yellow():
+    """Stamina 30-59% renders yellow gauge."""
+    player = Player(
+        name="Test",
+        stamina=45.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # Should have yellow color code
+    assert "\033[33m<45%>\033[0m" in result
+
+
+def test_stamina_gauge_red():
+    """Stamina < 30% renders red gauge."""
+    player = Player(
+        name="Test",
+        stamina=20.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # Should have red color code
+    assert "\033[31m<20%>\033[0m" in result
+
+
+def test_stamina_gauge_boundary_60():
+    """Stamina exactly 60% renders green."""
+    player = Player(
+        name="Test",
+        stamina=60.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # Should have green color code
+    assert "\033[32m<60%>\033[0m" in result
+
+
+def test_stamina_gauge_boundary_30():
+    """Stamina exactly 30% renders yellow."""
+    player = Player(
+        name="Test",
+        stamina=30.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # Should have yellow color code
+    assert "\033[33m<30%>\033[0m" in result
+
+
+def test_stamina_gauge_boundary_29():
+    """Stamina at 29% renders red."""
+    player = Player(
+        name="Test",
+        stamina=29.5,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    # Should have red color code
+    assert "\033[31m<29%>\033[0m" in result
+
+
+def test_zero_max_stamina():
+    """Zero max_stamina doesn't crash."""
+    player = Player(
+        name="Test",
+        stamina=0.0,
+        max_stamina=0.0,
+        pl=200.0,
+        mode_stack=["normal"],
+    )
+    result = render_prompt(player)
+    assert "0%" in result
+
+
+def test_name_variable():
+    """Name variable substitutes player name."""
+    player = Player(
+        name="Goku",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+        prompt_template="{name} > ",
+    )
+    result = render_prompt(player)
+    assert result == "Goku > "
+
+
+def test_mode_variable():
+    """Mode variable substitutes current mode."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal", "combat"],
+        prompt_template="[{mode}] > ",
+    )
+    result = render_prompt(player)
+    assert result == "[combat] > "
+
+
+def test_coordinates_variables():
+    """X and Y variables substitute coordinates."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+        x=42,
+        y=13,
+        prompt_template="({x},{y}) > ",
+    )
+    result = render_prompt(player)
+    assert result == "(42,13) > "
+
+
+def test_combat_state_idle():
+    """Combat state is 'idle' when not in combat."""
+    player = Player(
+        name="Test",
+        stamina=50.0,
+        max_stamina=100.0,
+        pl=200.0,
+        mode_stack=["normal"],
+        prompt_template="[{combat_state}] > ",
+    )
+    result = render_prompt(player)
+    assert result == "[idle] > "