fix(memory): add hindsight_client import check for local_external mode

[CipherFrame]

Problem

In local_external mode, is_available() returns True unconditionally (line 602-603), causing hermes memory status to report Hindsight as "available ✓" even when the hindsight-client Python package is not installed in the runtime.

This creates a false-positive that only surfaces at runtime when hindsight_recall / hindsight_reflect tools fail with:

ModuleNotFoundError: No module named 'hindsight_client'

This is especially confusing in Docker deployments where:

• The external Hindsight backend is healthy (health check passes, direct REST works)
• hermes memory status says everything is fine
• But the actual TUI/gateway tools crash

The root cause: #18924 proposed a fix for this but was closed without merging. The local_external branch of is_available() never got the import guard that local_embedded has via _check_local_runtime().

Fix

Add an importlib.import_module("hindsight_client") guard to the local_external branch. If the package is missing, log a warning and return False so hermes memory status accurately reflects reality.

if mode == "local_external":
    try:
        importlib.import_module("hindsight_client")
    except ImportError:
        logger.warning(
            "hindsight-client package is not installed. "
            "Install it with: uv pip install hindsight-client"
        )
        return False
    return True

This is a minimal, targeted fix — 8 lines, one file, no new dependencies.

Testing

Field-tested in a Docker Compose deployment:

• Without hindsight-client: is_available() returns False with warning log → status no longer lies
• With hindsight-client installed via uv: is_available() returns True → tools work correctly

Refs: #18876

[alt-glitch]

Duplicate of #18882 which already guards is_available() for cloud/local_external modes with the same hindsight_client import check. Also overlaps with closed #22586 (same fix). See also #24353 (local_external health check probes).

[teknium1]

Thanks for the focused report and minimal patch. The runtime failure described here is already addressed on current main by a later lazy-install implementation.

• Automated hermes-sweeper review verified plugins/memory/hindsight/__init__.py:1054-1055 calls _ensure_cloud_client_dependency() before importing hindsight_client; local_external uses that non-embedded path.
• Regression coverage at tests/plugins/memory/test_hindsight_provider.py:298-301 specifically verifies the local_external path ensures memory.hindsight before the client import.
• Commit 6c44471bfdb8a243200abe7aac44371727fda5ca (fix(hindsight): lazy-install cloud client dependency) shipped in v2026.6.19.
• The Docker-specific dependency gap from the discussion was also fixed by 96f0ddc6a946156c3f6d7151055329c0a99fec39, which bakes --extra hindsight into Dockerfile:183.

The proposed is_available() import guard would cause agent/agent_init.py:1393-1394 to skip provider activation before the lazy installer can run. Closing as implemented on main.