diff --git a/.env.example b/.env.example
index a7ae7af..40451f7 100644
--- a/.env.example
+++ b/.env.example
@@ -20,6 +20,24 @@ DEBUG=false
 # Logging level: DEBUG, INFO, WARNING, ERROR, CRITICAL
 LOG_LEVEL=INFO
 
+# Per-module log level overrides (optional)
+# These override LOG_LEVEL for specific modules.
+# LOG_LEVEL_GAME=DEBUG       # Core game logic
+# LOG_LEVEL_AI=DEBUG         # AI decisions (very verbose at DEBUG)
+# LOG_LEVEL_HANDLERS=DEBUG   # WebSocket message handlers
+# LOG_LEVEL_ROOM=DEBUG       # Room/lobby management
+# LOG_LEVEL_AUTH=DEBUG       # Auth stack (auth, routers.auth, services.auth_service)
+# LOG_LEVEL_STORES=DEBUG     # Database/Redis operations
+
+# --- Preset examples ---
+# Staging (debug game logic, quiet everything else):
+#   LOG_LEVEL=INFO
+#   LOG_LEVEL_GAME=DEBUG
+#   LOG_LEVEL_AI=DEBUG
+#
+# Production (minimal logging):
+#   LOG_LEVEL=WARNING
+
 # Environment name (development, staging, production)
 ENVIRONMENT=development
 
diff --git a/docs/v3/V3_18_POSTGRES_STORAGE_EFFICIENCY.md b/docs/v3/V3_18_POSTGRES_STORAGE_EFFICIENCY.md
new file mode 100644
index 0000000..99b99d6
--- /dev/null
+++ b/docs/v3/V3_18_POSTGRES_STORAGE_EFFICIENCY.md
@@ -0,0 +1,57 @@
+# V3.18: PostgreSQL Game Data Storage Efficiency
+
+**Status:** Planning
+**Priority:** Medium
+**Category:** Infrastructure / Performance
+
+## Problem
+
+Per-move game logging stores full `hand_state` and `visible_opponents` JSONB on every move. For a typical 6-player, 9-hole game this generates significant redundant data since most of each player's hand doesn't change between moves.
+
+## Areas to Investigate
+
+### 1. Delta Encoding for Move Data
+
+Store only what changed from the previous move instead of full state snapshots.
+
+- First move of each round stores full state (baseline)
+- Subsequent moves store only changed positions (e.g., `{"player_0": {"pos_2": "5H"}}`)
+- Replay reconstruction applies deltas sequentially
+- Trade-off: simpler queries vs. storage savings
+
+### 2. PostgreSQL TOAST and Compression
+
+- TOAST already compresses large JSONB values automatically
+- Measure actual on-disk size vs. logical size for typical game data
+- Consider whether explicit compression (e.g., storing gzipped blobs) adds meaningful savings over TOAST
+
+### 3. Retention Policy
+
+- Archive completed games older than N days to a separate table or cold storage
+- Configurable retention period via env var (e.g., `GAME_LOG_RETENTION_DAYS`)
+- Keep aggregate stats even after pruning raw move data
+
+### 4. Move Logging Toggle
+
+- Env var `GAME_LOGGING_ENABLED=true|false` to disable move-level logging entirely
+- Useful for non-analysis environments (dev, load testing)
+- Game outcomes and stats would still be recorded
+
+### 5. Batch Inserts
+
+- Buffer moves in memory and flush periodically instead of per-move INSERT
+- Reduces database round-trips during active games
+- Risk: data loss if server crashes mid-game (acceptable for non-critical move logs)
+
+## Measurements Needed
+
+Before optimizing, measure current impact:
+
+- Average JSONB size per move (bytes)
+- Average moves per game
+- Total storage per game (moves + overhead)
+- Query patterns: how often is per-move data actually read?
+
+## Dependencies
+
+- None (independent infrastructure improvement)
diff --git a/server/.env.example b/server/.env.example
index 6cb1716..fdeea33 100644
--- a/server/.env.example
+++ b/server/.env.example
@@ -7,6 +7,24 @@ PORT=8000
 DEBUG=true
 LOG_LEVEL=DEBUG
 
+# Per-module log level overrides (optional)
+# These override LOG_LEVEL for specific modules.
+# LOG_LEVEL_GAME=DEBUG       # Core game logic
+# LOG_LEVEL_AI=DEBUG         # AI decisions (very verbose at DEBUG)
+# LOG_LEVEL_HANDLERS=DEBUG   # WebSocket message handlers
+# LOG_LEVEL_ROOM=DEBUG       # Room/lobby management
+# LOG_LEVEL_AUTH=DEBUG       # Auth stack (auth, routers.auth, services.auth_service)
+# LOG_LEVEL_STORES=DEBUG     # Database/Redis operations
+
+# --- Preset examples ---
+# Staging (debug game logic, quiet everything else):
+#   LOG_LEVEL=INFO
+#   LOG_LEVEL_GAME=DEBUG
+#   LOG_LEVEL_AI=DEBUG
+#
+# Production (minimal logging):
+#   LOG_LEVEL=WARNING
+
 # Environment (development, staging, production)
 # Affects logging format, security headers (HSTS), etc.
 ENVIRONMENT=development
diff --git a/server/logging_config.py b/server/logging_config.py
index c8ce052..58a656a 100644
--- a/server/logging_config.py
+++ b/server/logging_config.py
@@ -148,6 +148,39 @@ class DevelopmentFormatter(logging.Formatter):
         return output
 
 
+# Per-module log level overrides via env vars.
+# Key: env var suffix, Value: list of Python logger names to apply to.
+MODULE_LOGGER_MAP = {
+    "GAME": ["game"],
+    "AI": ["ai"],
+    "HANDLERS": ["handlers"],
+    "ROOM": ["room"],
+    "AUTH": ["auth", "routers.auth", "services.auth_service"],
+    "STORES": ["stores"],
+}
+
+
+def _apply_module_overrides() -> dict[str, str]:
+    """
+    Apply per-module log level overrides from LOG_LEVEL_{MODULE} env vars.
+
+    Returns:
+        Dict of module name -> level for any overrides that were applied.
+    """
+    active = {}
+    for module, logger_names in MODULE_LOGGER_MAP.items():
+        env_val = os.environ.get(f"LOG_LEVEL_{module}", "").upper()
+        if not env_val:
+            continue
+        level = getattr(logging, env_val, None)
+        if level is None:
+            continue
+        active[module] = env_val
+        for name in logger_names:
+            logging.getLogger(name).setLevel(level)
+    return active
+
+
 def setup_logging(
     level: str = "INFO",
     environment: str = "development",
@@ -182,12 +215,19 @@ def setup_logging(
     logging.getLogger("websockets").setLevel(logging.WARNING)
     logging.getLogger("asyncio").setLevel(logging.WARNING)
 
+    # Apply per-module overrides from env vars
+    overrides = _apply_module_overrides()
+
     # Log startup
     logger = logging.getLogger(__name__)
     logger.info(
         f"Logging configured: level={level}, environment={environment}",
         extra={"level": level, "environment": environment},
     )
+    if overrides:
+        logger.info(
+            f"Per-module log level overrides: {', '.join(f'{m}={l}' for m, l in overrides.items())}",
+        )
 
 
 class ContextLogger(logging.LoggerAdapter):