feat: log Kit version info on AppLauncher startup

[pv-nvidia]

Summary

Prints Kit version, kernel version, and git hash to stderr after AppLauncher initialization completes.

Motivation

While debugging a multi-GPU CI issue (#5822), we discovered the CI was silently using Kit 110.0 (from a stale pip-installed isaacsim==6.0.0) instead of Kit 111.0 from the container. Having version info printed on every startup would have caught this immediately.

Changes

• Added _log_kit_version_info() method to AppLauncher
• Called after AppLauncher initialization complete message
• Prints to sys.__stderr__ (same stream as the init-complete signal)
• Falls back to "unknown" if the git hash token is not defined

Example output

[ISAACLAB] AppLauncher initialization complete
[ISAACLAB] Kit version: 111.0.0+develop.12345.abcdef01.gl
[ISAACLAB] Kit kernel:  211.0.0+release.12345.abcdef01.gl
[ISAACLAB] Kit hash:    abcdef01

[greptile-apps]

Greptile Summary

This PR adds a _log_kit_version_info() method to AppLauncher that prints Kit version, kernel version, and git hash to sys.__stderr__ immediately after the "initialization complete" signal, aiding CI diagnostics for version mismatch issues.

• Version logging: Three lines are printed to sys.__stderr__ using omni.kit.app and carb.tokens APIs — consistent with the existing init-complete signal pattern.
• No exception safety: The helper is called unconditionally inside __init__ with no try/except guard; any API failure will propagate and crash AppLauncher startup rather than degrading gracefully.
• Token fallback: The or "unknown" guard on tokens.resolve("${kit_git_hash}") may not fire if carb returns the literal unresolved placeholder string for undefined tokens.

Confidence Score: 4/5

The change is a pure diagnostic addition, but calling the helper unconditionally in __init__ without exception handling means any carb/omni API failure will crash AppLauncher startup.

The new _log_kit_version_info method performs several API calls (omni.kit.app.get_app, carb.tokens.get_tokens_interface, get_kit_version, get_kernel_version, tokens.resolve) with no try/except guard. An unhandled exception from any of these propagates directly through AppLauncher.__init__, turning a diagnostic-only feature into a potential startup blocker across Kit versions or environments where the APIs behave differently.

source/isaaclab/isaaclab/app/app_launcher.py — the _log_kit_version_info method and its call site in __init__

Important Files Changed

Filename	Overview
source/isaaclab/isaaclab/app/app_launcher.py	Adds _log_kit_version_info() called unconditionally in __init__; any exception from the carb/omni.kit.app APIs will propagate and crash AppLauncher startup rather than silently degrading.
source/isaaclab/changelog.d/pv-log-kit-version.rst	New changelog entry describing the Kit version logging addition — no issues.

Sequence Diagram

sequenceDiagram
    participant Caller
    participant AppLauncher.__init__
    participant omni.kit.app
    participant carb.tokens
    participant sys.__stderr__

    Caller->>AppLauncher.__init__: AppLauncher(args)
    AppLauncher.__init__->>sys.__stderr__: "AppLauncher initialization complete"
    AppLauncher.__init__->>AppLauncher.__init__: _log_kit_version_info()
    AppLauncher.__init__->>omni.kit.app: get_app()
    omni.kit.app-->>AppLauncher.__init__: app
    AppLauncher.__init__->>carb.tokens: get_tokens_interface()
    carb.tokens-->>AppLauncher.__init__: tokens
    AppLauncher.__init__->>omni.kit.app: app.get_kit_version()
    omni.kit.app-->>AppLauncher.__init__: kit_version
    AppLauncher.__init__->>omni.kit.app: app.get_kernel_version()
    omni.kit.app-->>AppLauncher.__init__: kernel_version
    AppLauncher.__init__->>carb.tokens: tokens.resolve(kit_git_hash)
    carb.tokens-->>AppLauncher.__init__: hash or literal placeholder
    AppLauncher.__init__->>sys.__stderr__: Kit version / kernel / hash lines
    AppLauncher.__init__-->>Caller: AppLauncher instance

Loading

Comments Outside Diff (1)

1. source/isaaclab/isaaclab/app/app_launcher.py, line 1229-1243 (link)

   Unhandled exception breaks AppLauncher startup

   _log_kit_version_info has no exception handling, and it is called unconditionally inside __init__. Any failure here — ImportError on carb/omni.kit.app, AttributeError if an API is missing in a different Kit version, or a runtime error from get_tokens_interface() — will propagate and crash AppLauncher initialization entirely. Since this is a pure diagnostic helper, its failure should never block startup. The method should be wrapped in a broad except Exception that falls back to a short message on sys.__stderr__ so the intent is preserved even in error paths.

_{Reviews (2): Last reviewed commit: "Merge branch 'develop' into pv/log-kit-v..." | Re-trigger Greptile}