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+# Admin & Log Panel Design
+
+## Overview
+
+Add two new tabs to the left panel: an Admin tab (A) for runtime constant editing behind password authentication, and a Log tab (L) for streaming server-side operational logs.
+
+## Admin Tab
+
+### Authentication
+- Password-gated: "dwarf" hardcoded server-side (will move to .env later)
+- Authenticated once per session; stays unlocked until page refresh
+- Server validates password via `admin-auth` socket event, never trusts client
+
+### Constant Editor
+- Exposes gameplay tuning constants only (not world size, asset/rendering):
+  - Tick rates: TICK_RATE, BROADCAST_EVERY_N_TICKS
+  - Needs: HUNGER_DECAY_PER_TICK, ENERGY_DECAY_PER_TICK, HUNGER_THRESHOLD, ENERGY_THRESHOLD
+  - Sleep: ENERGY_RECOVERY_PER_TICK, WAKE_THRESHOLD, VOLUNTARY_SLEEP_THRESHOLD
+  - Day/night: DAY_DURATION_SECONDS, DAY_NIGHT_RATIO
+  - Social: AWARENESS_RADIUS, FACING_DURATION, PAUSING_DURATION, EMOTING_DURATION, COOLDOWN_DURATION
+- Each constant displayed as: label, editable number input, muted default value
+- Changes apply immediately (debounced ~300ms)
+- "Reset to Defaults" button restores all to compiled defaults
+
+### Protocol
+- `admin-auth` (client→server): { password } → { success, constants? }
+- `admin-update-constant` (client→server): { key, value } → server validates and applies
+- `admin-reset-defaults` (client→server): resets all to defaults
+- `admin-constants-updated` (server→client): full current constants object
+
+### Server: Runtime Constants
+- `server/src/config/runtimeConstants.ts`: initializes from shared constants
+- Exposes `getRuntimeConstants()`, `updateConstant(key, value)`, `resetDefaults()`
+- Stores original defaults for reset
+- Systems switch imports from shared constants to runtime constants object
+
+## Log Tab
+
+### UI
+- Scrollable reverse-chronological log entries
+- Each entry: wall-clock timestamp, severity (error/warning/info), category tag, message
+- Severity color-coded: red (error), yellow (warning), blue (info)
+- Category tags: LLM, Save, Network, Performance, Game
+
+### Protocol (subscribe/unsubscribe pattern)
+- `log-subscribe` (client→server): starts streaming → server sends `log-history` (recent buffer)
+- `log-entry` (server→client): pushed while subscribed
+- `log-unsubscribe` (client→server): stops streaming
+
+### Server: LogService
+- Ring buffer of last 200 entries
+- `log(severity, category, message)` method
+- Tracks subscribed sockets, pushes only to subscribers
+
+### Log Sources (11 categories)
+1. **LLM failures** — HTTP errors, bad responses
+2. **LLM timeouts** — 15s default exceeded
+3. **LLM rate limits** — 429 responses, fallback model switches
+4. **LLM parse failures** — JSON parse errors on backstory/desire/invention responses
+5. **LLM token milestones** — every 100 requests summary
+6. **Save/load errors** — SQLite write failures, schema migration issues
+7. **Serialization failures** — component data that can't serialize/deserialize
+8. **NPC spawn failures** — appearance generation or ID assignment errors
+9. **Player connect/disconnect** — network join/leave events
+10. **Socket errors** — unexpected disconnects
+11. **Tick overruns** — game tick exceeds tick interval duration
+
+## Integration
+
+### Left Panel
+- Grows from 4 tabs (S/E/I/R) to 6 tabs (S/E/I/R/L/A)
+- New files: `client/src/ui/AdminPanel.ts`, `client/src/ui/LogPanel.ts`
+- Passed to LeftPanel constructor like existing content panels
+
+### Shared Types
+- New socket event types added to `shared/src/types.ts`
+- `TunableConstants` interface for the editable constant subset
+
+### Unchanged
+- Right-side NPC info panel
+- Existing 4 left panel tab content
+- Game system behavior (just reads from runtime constants instead of imports)