Docs: refresh README for the full 2.1.0 surface

Cover every resource/method: models; connector writes (types/create/test/
update/delete); sandbox list/executions/exec/files/library + query params and
start(sandbox_id); add an Errors section and context-manager usage.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: jlsajfj

README.md

@@ -31,10 +31,7 @@ for event in client.chat.stream("Summarize sales by region"):
         print(event["text"], end="", flush=True)
 
 # Upload files with a question
-response = client.chat.create(
-    "Analyze this data",
-    files=["./sales.csv"],
-)
+response = client.chat.create("Analyze this data", files=["./sales.csv"])
 ```
 
 ## Resources
@@ -43,43 +40,101 @@ response = client.chat.create(
 
 ```python
 client.chat.list(limit=10)
-client.chat.create("What connectors are available?")
+client.chat.create("What connectors are available?", connector_ids=[1])
+client.chat.create("Analyze this", files=["./data.csv"])   # multipart upload
+client.chat.stream("Summarize revenue")                     # returns a Stream iterator
 client.chat.get("chat-uuid")
-client.chat.stream("Summarize revenue")
 client.chat.cancel("chat-uuid")
 ```
 
 ### Connectors
 
+`config` is the connector configuration as documented by `types()` — `connector_type`
+plus a per-type block (e.g. `postgres`, `kdb`, `snowflake`).
+
 ```python
 client.connectors.list()
+client.connectors.types()   # every connector type and its fields (self-describing)
+
+cfg = {
+    "connector_type": "POSTGRES",
+    "name": "prod-db",
+    "postgres": {"host": "db.example.com", "port": 5432, "user": "ro", "password": "...", "database": "app"},
+}
+client.connectors.test(cfg)                       # {"success": bool, "error": str} — a failed connection is success=False, not an error
+created = client.connectors.create(cfg, allow_sql_write_operations=False)
+client.connectors.update(created["connector_id"], cfg)
+client.connectors.delete(created["connector_id"])
+```
+
+### Models
+
+```python
+client.models.list()   # models a key may pass as the chat `model` field
 ```
 
 ### Playbooks
 
 ```python
 client.playbooks.list(limit=10)
 pb = client.playbooks.create()
+client.playbooks.get(pb["id"])
 client.playbooks.update(pb["id"], name="Weekly Revenue", prompt="Summarize revenue by region")
 client.playbooks.deploy(pb["id"])
-client.playbooks.run(pb["id"])
-client.playbooks.get(pb["id"])
+client.playbooks.run(pb["id"])           # run(..., dry_run=True) to validate without sending
 client.playbooks.delete(pb["id"])
 ```
 
 ### Sandbox
 
+A sandbox is a stateful Python/SQL workspace. Start one, run code or load connector
+data into DataFrames, manage its files, then stop it.
+
 ```python
-sb = client.sandbox.start()
+sb = client.sandbox.start()              # start(sandbox_id="...") restarts a specific one
 sid = sb["sandbox_id"]
 
+client.sandbox.list(status="all")        # also: limit=, cursor=
+client.sandbox.status(sid)
+client.sandbox.executions(sid)           # recorded run history (limit=, cursor=)
+
+# Run code / commands
 client.sandbox.execute(sid, code="import pandas as pd; print(pd.__version__)")
+client.sandbox.exec(sid, command="ls -la")               # bash by default
+client.sandbox.exec(sid, command="print('hi')", kind="python")
+
+# Load connector data into a DataFrame (exactly one of query / tql_path)
 client.sandbox.query(sid, connector_id=1, query="SELECT * FROM sales LIMIT 10", dataframe_name="sales")
+client.sandbox.query(sid, connector_id=2, tql_path="portfolio/current_positions.tql", params={"as_of": "2026-01-01"}, max_rows=500)
+
+# Files
 client.sandbox.upload_file(sid, "./data.csv")
-client.sandbox.status(sid)
+client.sandbox.list_files(sid)                           # path="subdir" to scope
+content: bytes = client.sandbox.download_file(sid, "out/report.csv")
+client.sandbox.delete_file(sid, "out/report.csv")
+
+# Library write-back
+client.sandbox.library_diff(sid)
+client.sandbox.create_library_patch(sid, title="Add metric", description="...", draft=True)
+
 client.sandbox.stop(sid)
 ```
 
+## Errors
+
+Non-2xx responses raise typed exceptions, all subclasses of `textql.APIError`:
+
+```python
+from textql import TextQL, NotFoundError, RateLimitError, AuthenticationError
+
+try:
+    client.chat.get("does-not-exist")
+except NotFoundError as e:
+    print(e.status_code, e.request_id)
+```
+
+Also exported: `PermissionDeniedError`, `APITimeoutError`, `APIConnectionError`.
+
 ## Configuration
 
 | Option | Env var | Default |
@@ -88,7 +143,13 @@ client.sandbox.stop(sid)
 | `base_url` | `TEXTQL_BASE_URL` | `https://app.textql.com` |
 | `timeout` | — | `60.0` seconds |
 
-The `base_url` accepts a bare hostname (e.g. `app.textql.com`) or a full URL.
+The `base_url` accepts a bare hostname (e.g. `app.textql.com`) or a full URL. The
+client is a context manager:
+
+```python
+with TextQL(api_key="tql_...") as client:
+    client.connectors.list()
+```
 
 ## Links