fix(memory): auto-install hindsight-all for local_embedded mode

[LehaoLin]

What does this PR do?

Fixes a crash when users select local_embedded mode via hermes memory setup. The setup wizard tries to install hindsight-all but the install can silently fail because capture_output=True swallows errors. Since plugin.yaml only declares hindsight-client>=0.4.22 as a dependency, hermes startup validation passes even when hindsight-all is missing. At runtime, from hindsight import HindsightEmbedded crashes with ModuleNotFoundError: No module named 'hindsight'.

This patch adds a guard in HindsightMemoryProvider.initialize() that:

1. Detects when mode is local_embedded
2. Attempts to import hindsight — if it fails, auto-installs hindsight-all via uv pip install
3. Raises a clear RuntimeError with manual install instructions if installation fails
4. Does not surface errors as swallowed silent failures — errors are logged and propagated

This mirrors the existing auto-upgrade logic for hindsight-client already present in initialize() for cloud mode.

Related Issue

Fixes crash described in hindsight local_embedded setup flow.

Type of Change

• Bug fix (non-breaking change that fixes an issue)

Changes Made

• plugins/memory/hindsight/__init__.py: Added auto-install guard for hindsight-all in initialize() when mode is local_embedded
• plugins/memory/hindsight/plugin.yaml: Added comment documenting the hindsight-all dependency for local_embedded mode

How to Test

1. Configure hindsight with local_embedded mode but ensure hindsight-all is NOT installed
2. Start a new hermes session with hindsight memory enabled
3. Verify that the plugin auto-installs hindsight-all and logs the installation
4. Verify that if installation fails, a clear RuntimeError is raised with manual instructions
5. Test cloud mode still works without hindsight-all installed (no regression)

Checklist

• My commit messages follow Conventional Commits
• My PR contains only changes related to this fix
• I have considered cross-platform impact (uses shutil.which("uv") which works on all platforms)
• Updated relevant docstrings/comments — plugin.yaml comment added

[alt-glitch]

Overlaps with #7741 (fail-loudly approach) — both address #7718. This PR auto-installs instead of just erroring.

[alt-glitch]

Overlaps with #7741 (fail-loudly approach) — both address #7718. This PR auto-installs instead of just erroring.

[nicoloboschi]

we do it already when you do the hermes memory setup so I don't see why we need it twice

[teknium1]

Thanks for addressing the local-embedded dependency path. Current main now prevents the PR-era repeated missing-module failure by probing the local runtime and disabling it with a warning when unavailable (plugins/memory/hindsight/__init__.py:1269-1280), but it still does not self-heal manually configured installations.

Problems

• The added guard checks only import hindsight. Current runtime use requires both hindsight and hindsight_embed.daemon_embed_manager (plugins/memory/hindsight/__init__.py:127-140), so a partial installation can bypass the installer and still be disabled at initialization.
• The PR diff adds no regression tests for install success/failure or the partial-runtime case.
• Its manual command omits the active interpreter target, unlike the existing setup guidance at plugins/memory/hindsight/__init__.py:828-839.

Suggested changes

• Rework this around the full runtime probe, auto-installing only for a verified missing dependency and preserving the current fail-disabled behavior for incompatible runtimes.
• Re-probe after installation and add focused tests for recovery, install failure, and no effect on cloud/local_external modes.

Automated hermes-sweeper review.

[kshitijk4poor]

Merged via #85494 — the local_embedded missing-dependency issue (#7718) is addressed with an actionable install hint surfaced through the unavailable_reason() hook. Thanks for the alternative approach!