feat(cli): add keep_latest prune strategy to ThreadTTLConfig (#6784)

## Summary
- Add `"keep_latest"` to `ThreadTTLConfig.strategy` to match
langgraph-api support for pruning old checkpoints while retaining the
thread and its latest state
- Add `sweep_limit` to `ThreadTTLConfig` where the API actually reads it
(was previously a no-op on `CheckpointerConfig`)
- Regenerate `schema.json` / `schema.v0.json`

## Test plan
- [x] `make format && make lint` passes
- [x] `make test` passes (85/85)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

libs/cli/langgraph_cli/config.py

@@ -196,6 +196,11 @@ def validate_config(config: Config) -> Config:
                 f"Python version {pyversion} is not supported. "
                 f"Minimum required version is {MIN_PYTHON_VERSION}."
             )
+        if "bullseye" in pyversion:
+            raise click.UsageError(
+                "Bullseye images were deprecated in version 0.4.13. "
+                "Please use 'bookworm' or 'debian' instead."
+            )
 
         if not config["dependencies"]:
             raise click.UsageError(

libs/cli/langgraph_cli/schemas.py

@@ -107,17 +107,19 @@ class StoreConfig(TypedDict, total=False):
 class ThreadTTLConfig(TypedDict, total=False):
     """Configure a default TTL for checkpointed data within threads."""
 
-    strategy: Literal["delete"]
-    """Strategy to use for deleting checkpointed data.
-    
-    Choices:
-      - "delete": Delete all checkpoints for a thread after TTL expires.
+    strategy: Literal["delete", "keep_latest"]
+    """Action taken when a thread exceeds its TTL.
+
+    - "delete": Remove the thread and all its data entirely.
+    - "keep_latest": Prune old checkpoints but keep the thread and its latest state.
     """
     default_ttl: float | None
     """Default TTL (time-to-live) in minutes for checkpointed data."""
     sweep_interval_minutes: int | None
     """Interval in minutes between sweep iterations.
     If omitted, a default interval will be used (typically ~ 5 minutes)."""
+    sweep_limit: int | None
+    """Maximum number of threads to process per sweep iteration. Defaults to 1000."""
 
 
 class SerdeConfig(TypedDict, total=False):
@@ -173,14 +175,12 @@ class CheckpointerConfig(TypedDict, total=False):
     """
     serde: SerdeConfig | None
     """Optional. Defines the serde configuration.
-    
+
     If provided, the checkpointer will apply serde settings according to the configuration.
     If omitted, no serde behavior is configured.
 
     This configuration requires server version 0.5 or later to take effect.
     """
-    sweep_limit: int | None
-    """Maximum number of threads to process per sweep iteration. Defaults to 1000."""
 
 
 class SecurityConfig(TypedDict, total=False):