docs: Remove deprecated headless examples for beta2

[AntoineRichard]

Description

Backport of #6102 to release/3.0.0-beta2.

Removes deprecated --headless from documentation examples and clarifies that omitting --visualizer / --viz is the default headless path. Uses --visualizer none / --viz none only for forced-disable cases when a config or command selects a visualizer.

No new dependencies.

Fixes # N/A

Type of change

• Documentation update

Screenshots

N/A.

Checklist

• I have read and understood the contribution guidelines
• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works (N/A, documentation-only)
• I have added a changelog fragment under source/<pkg>/changelog.d/ for every touched package (do not edit CHANGELOG.rst or bump extension.toml — CI handles that)
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[isaaclab-review-bot]

Review Summary

Clean documentation PR that systematically removes the deprecated --headless flag across 44 files and provides correct guidance for the new --visualizer / --viz pattern. The changes are consistent and well-structured.

CI Status: Pre-commit, changelog, broken link, and wheel build checks all pass ✅

Findings

#	Severity	File	Issue
1	🟠 Medium	docs/source/policy_deployment/00_hover/hover_policy.rst	Dangling trailing backslashes after --headless removal (3 occurrences)
2	🟡 Minor	docs/source/features/hydra.rst	Stale prose references "headless mode" after flag removal
3	🟢 Nit	docs/source/setup/quickstart.rst	Replacement text is slightly verbose for the context

Details

1. Dangling trailing backslashes in hover_policy.rst 🟠

In three multi-line commands, --headless was the final argument (no trailing \ of its own), but the preceding line has a trailing \ for continuation. After removal, the last line of the command now ends with \ followed by a blank line, which is a broken shell command in the rendered example.

Affected locations (lines ~60, ~75, ~168):

# Before (correct):
${ISAACLAB_PATH:?}/isaaclab.sh -p scripts/rsl_rl/train_teacher_policy.py     --num_envs 1024     --reference_motion_path neural_wbc/data/data/motions/stable_punch.pkl     --headless

# After (dangling backslash):
${ISAACLAB_PATH:?}/isaaclab.sh -p scripts/rsl_rl/train_teacher_policy.py     --num_envs 1024     --reference_motion_path neural_wbc/data/data/motions/stable_punch.pkl ```

**Fix:** Remove the trailing `\` from the line that is now the last argument in each of the 3 commands.

#### 2. Stale prose in `hydra.rst` 🟡

The paragraph after the code examples still reads:
> "The above command will run training with the task ``Isaac-Cartpole`` **in headless mode**, and set the..."

Since `--headless` was removed from the commands, this should be updated (e.g., "without a visualizer" or simply remove "in headless mode").

#### 3. Verbose replacement in `quickstart.rst` 🟢

The new text is a 160+ character single line:
> "For commands that do not configure a visualizer, omit `--visualizer` / `--viz` to run without a viewer. Use `--help` on any script to see task-specific..."

Consider splitting across two lines or simplifying to stay within typical RST line-length conventions. This is purely cosmetic.

---

Overall a well-executed cleanup. The dangling backslashes in hover_policy.rst are the only issue that would produce incorrect rendered examples for users copying commands.

[isaaclab-review-bot]

Stale prose: The --headless flag was removed from all four command examples above, but this sentence still reads:

The above command will run training with the task Isaac-Cartpole in headless mode, and set the…

Since the commands no longer explicitly pass any headless/visualizer flag, this text is now misleading. Consider updating to something like:

The above command will run training with the task ``Isaac-Cartpole`` (without a visualizer by default) and set the…

Or simply remove the "in headless mode" qualifier.

[greptile-apps]

Greptile Summary

This PR backports #6102 to release/3.0.0-beta2, removing the deprecated --headless CLI flag from all documentation examples and replacing it with the new Isaac Lab 3.0 convention: omitting --visualizer / --viz is the default no-viewer path, while --visualizer none / --viz none is reserved for explicitly disabling a visualizer that a config or command would otherwise select.

• 44 documentation files updated across tutorials, migration guides, deployment, RL framework examples, imitation-learning, benchmarks, and policy-deployment pages — all --headless occurrences in code blocks replaced consistently.
• Descriptive prose updated in most files to explain the new headless convention; a few files add inline notes (e.g. run_docker_example.rst, simulation_performance.rst) clarifying when --viz none is needed.
• launch_app.rst updates the simulated --help output to drop the deprecated flag and rewrites surrounding prose to remove references to --headless semantics.

Confidence Score: 5/5

Documentation-only change with no code modifications; safe to merge.

All 44 changed files are .rst / .md / .skip documentation files. The changes are mechanical and consistent — removing --headless from code blocks and updating surrounding prose. The one minor gap is that hydra.rst still describes the example commands as running in headless mode without explaining the new default-headless contract, which could leave readers puzzled, but this does not affect runtime behaviour.

docs/source/features/hydra.rst — the explanatory sentence on line 51 still references headless mode without clarifying that this now means omitting the visualizer flag rather than passing --headless.

Important Files Changed

Filename	Overview
docs/source/features/hydra.rst	Removed --headless from all four RL-library tab items; descriptive sentence on line 51 still references "in headless mode" without explaining the new default-headless behaviour.
docs/source/deployment/run_docker_example.rst	Removed --headless and updated prose to explain the default-headless path; added a note on --visualizer none / --viz none for forced-disable cases.
docs/source/tutorials/00_sim/launch_app.rst	Removed --headless from the simulated --help output, removed the deprecated flag description, and updated the experience-file note to use neutral "launch mode" language.
docs/source/testing/benchmarks.rst	Removed --headless from four benchmark commands and dropped the --headless row from the Common Arguments table; clean and consistent.
docs/source/overview/reinforcement-learning/rl_existing_scripts.rst	Removed --headless from all RL-library training/play examples across Linux/Windows tabs; no regressions.
docs/source/policy_deployment/02_gear_assembly/gear_assembly_policy.rst	Removed --headless from training, debugging, and troubleshooting examples; also removed the "Command breakdown" bullet that described --headless.
docs/source/overview/imitation-learning/humanoids_imitation.rst	Removed --headless from three dataset-generation commands; the command that retains --visualizer kit is unaffected and correct.
source/isaaclab_teleop/changelog.d/docs-headless-examples.skip	Empty skip file added to suppress changelog generation for this docs-only change; intentional and correct.
source/isaaclab_teleop/docs/README.md	Updated headless instruction to replace --headless with --visualizer none / --viz none, consistent with the RST counterpart.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[User runs isaaclab command] --> B{Does command or config\nselect a visualizer?}
    B -- No --> C[Runs headless by default\nomit --visualizer / --viz]
    B -- Yes --> D{Want headless?}
    D -- No --> E[Visualizer launches normally\ne.g. --visualizer kit]
    D -- Yes --> F[Force disable visualizer\n--visualizer none / --viz none]

    style C fill:#d4edda,stroke:#28a745
    style F fill:#fff3cd,stroke:#ffc107
    style E fill:#cce5ff,stroke:#004085

Loading

_{Reviews (1): Last reviewed commit: "docs: Clarify visualizer override guidan..." | Re-trigger Greptile}

[greptile-apps]

Stale "headless mode" description after flag removal

The prose still says "The above command will run training with the task Isaac-Cartpole in headless mode" but the --headless flag was removed from all four tab items above and no explicit --viz none was added. Readers following this tutorial won't understand how headless behaviour is achieved without additional context explaining that omitting --visualizer / --viz is the default no-viewer path in Isaac Lab 3.0-beta2. The phrase should either be updated to say "without a visualizer (the default)" or a brief note like the one added in other files should be included.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

[isaaclab-review-bot]

Dangling trailing backslash: Now that --headless is removed, this line ends with \ but has nothing following it. This will render as a broken example for users.

Suggested change

	--reference_motion_path neural_wbc/data/data/motions/stable_punch.pkl \
	--reference_motion_path neural_wbc/data/data/motions/stable_punch.pkl

Same issue occurs two more times in this file (the student training command ~line 77 and the deployment command ~line 170).