Add stop token propagation tests and document inheritance behavior

[mvandeberg]

Closes #163

The run/run_async API already supports stop token injection, but this was undertested and underdocumented, making it appear missing.

Add tests verifying that run(ex) inherits the caller's stop token, run(ex, st) overrides it, and run_async propagates tokens to deferred tasks. Restructure the launching docs into a unified stop token propagation section and fix the download_manager example to use io_env propagation.

[coderabbitai]

Important

Review skipped

Review was skipped due to path filters

⛔ Files ignored due to path filters (4)

• doc/modules/ROOT/pages/4.coroutines/4b.launching.adoc is excluded by !**/doc/**
• doc/modules/ROOT/pages/4.coroutines/4e.cancellation.adoc is excluded by !**/doc/**
• test/unit/ex/run.cpp is excluded by !**/test/**
• test/unit/ex/run_async.cpp is excluded by !**/test/**

CodeRabbit blocks several paths by default. You can override this behavior by explicitly including those paths in the path filters. For example, including **/dist/** will override the default block on the dist directory, by removing the pattern from both the lists.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 6e6141f3-cab9-4c62-abaa-4a61d84ef575

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[cppalliance-bot]

An automated preview of the documentation is available at https://214.capy.prtest3.cppalliance.org/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-03-05 17:16:43 UTC

[cppalliance-bot]

GCOVR code coverage report https://214.capy.prtest3.cppalliance.org/gcovr/index.html
LCOV code coverage report https://214.capy.prtest3.cppalliance.org/genhtml/index.html
Coverage Diff Report https://214.capy.prtest3.cppalliance.org/diff-report/index.html

Build time: 2026-03-05 17:26:20 UTC

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.94%. Comparing base (5fc166e) to head (bcb682b).
⚠️ Report is 7 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #214   +/-   ##
========================================
  Coverage    91.94%   91.94%           
========================================
  Files           76       76           
  Lines         4504     4504           
========================================
  Hits          4141     4141           
  Misses         363      363           

see 2 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5fc166e...bcb682b. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.