docs: update README and ARCHITECTURE for v1.1.0 — litellm_history function

- README: three functions, litellm_history params and cost awareness note
- ARCHITECTURE: full Function 3 section with endpoint, fields, output format,
  token display rules, error paths, and performance considerations

ARCHITECTURE.md

@@ -5,7 +5,7 @@
 
 ## Product Definition
 
-A single Open WebUI **Tool** that provides LiteLLM proxy health status and cost breakdown. Designed for the Network but built for general use — any LiteLLM proxy instance.
+A single Open WebUI **Tool** that provides LiteLLM proxy health status, cost breakdown, and recent request history. Designed for the Network but built for general use — any LiteLLM proxy instance.
 
 ## OWI Integration Model
 
@@ -157,6 +157,67 @@ By Date:
 | Timeout (>30s) | Timeout message (large date ranges may be slow) |
 | No results | "No cost data found for [range]" |
 
+## Function 3: Request History
+
+**LiteLLM Endpoint:** `GET {litellm_url}/spend/logs`
+**Auth:** `Authorization: Bearer {litellm_master_key}`
+**Params:** `limit` (int, 1-50, default 20), `show_cost` (bool, default true)
+
+### Response Processing
+
+The `/spend/logs` endpoint returns **all** historical request logs (no server-side pagination). The tool sorts by `startTime` descending and takes the most recent `limit` entries client-side.
+
+**Performance note:** For large deployments (thousands of logs), this endpoint can be slow. The tool caps `limit` at 50 and uses a 30s timeout.
+
+### Per-Request Fields
+
+| Field | Description |
+|-------|-------------|
+| `request_id` | Unique request identifier |
+| `model` | Model used (provider prefix stripped for readability) |
+| `call_type` | Request type: `acompletion` → "chat", `aembedding` → "embed", `aimage_generation` → "image" |
+| `status` | ✅ OK if no exception, ❌ FAIL if exception present |
+| `startTime` | Request start timestamp |
+| `request_duration_ms` | Total duration |
+| `prompt_tokens` | Input tokens |
+| `completion_tokens` | Output tokens |
+| `cache_read_input_tokens` | Cache hit count |
+| `spend` | Cost in USD |
+| `metadata.exception` | Error message if failed |
+
+### Output Format
+
+```
+LiteLLM Request History — http://host.docker.internal:4000
+Showing 20 of 4560 total requests (most recent first)
+==========================================================================================
+   1. 06-05T01:15:27 | gemini-3.1-flash-image-previ | image      | ✅ OK |   15.0s | 96→1.6k | $0.0947
+   2. 06-05T01:12:27 | gemini-3.1-flash-image-previ | image      | ✅ OK |   13.3s | 101→1.5k | $0.0922
+   3. 06-05T01:11:35 |                              |            | ✅ OK |     0ms
+   4. 06-05T01:07:36 | gemini-3.5-flash             | chat       | ✅ OK |    8.8s | 149.8k→1.1k | $0.1821
+   ...
+
+  Summary (20 shown): $3.1493 spent | 2,798,587 prompt + 5,815 completion tokens | 0 failed
+```
+
+### Token Display Rules
+
+- Prompt tokens ≥ 1000: shown as "X.Xk" (e.g., 149.8k)
+- Completion tokens ≥ 1000: shown as "X.Xk"
+- Cache hit % shown as 💾 indicator when `cache_read_input_tokens > 0`
+- Zero-token entries (health checks, failed routing) shown without token info
+
+### Error Paths
+
+| Condition | Response |
+|-----------|----------|
+| No master key configured | Error — key required |
+| 401 Unauthorized | Auth failed message |
+| 403 Forbidden | Permission denied message |
+| Connection refused | Connection failed message |
+| Timeout (>30s) | Timeout message |
+| No logs | "No request history found" |
+
 ## Additional Endpoints (Future Consideration)
 
 | Endpoint | Purpose | Priority |
@@ -169,7 +230,7 @@ These are documented but not in scope for v1. The two-function design is the rig
 
 ## Design Principles
 
-1. **Two functions, that's it.** No scope creep. Health check and cost breakdown.
+1. **Three functions, that's it.** No scope creep. Health check, cost breakdown, request history.
 2. **Portable.** No hardcoded URLs or keys. Valves pass everything.
 3. **Token-efficient.** Strip litellm_metadata from health. Format cost data as readable text, not raw JSON dumps.
 4. **General-purpose.** Designed for the Network but usable by anyone with a LiteLLM proxy.