refactor!: rename the IoAwaitable family to context-based names

[sgerbino]

Problem

The awaitable protocol carries an execution context (executor, stop token, frame allocator), but its names say "I/O".

Renames

Old	New
IoAwaitable	ContextAwaitable
IoAwaitableRange	ContextAwaitableRange
IoRunnable	ContextRunnable
io_env	await_context
io_awaitable_promise_base	context_awaitable_promise_base
io_result	results
io_task<Ts...>	removed; write task<results<Ts...>>

Headers move to match: concept/context_awaitable.hpp, concept/context_runnable.hpp, ex/await_context.hpp, ex/context_awaitable_promise_base.hpp, results.hpp. io_task.hpp is deleted.

Derived names follow the same scheme, for example is_results_v, results_payload_t, the when_all/when_any *_results_* detail helpers, and the awaitable-sender example's context_sender_env / get_context_executor.

Docs

Every page, snippet, javadoc and reference example uses the new names. Pages whose file names carried the old names are renamed (4e.io-awaitable.adoc → 4e.context-awaitable.adoc, the unlisted io-awaitables-* pages), and the "Reporting Errors" anchor is now #reporting-errors. Published papers under papers/ are unchanged.

Downstream

corosio and http need matching changes on branches named pr/rename-foundation. Their CI builds against capy develop, so this PR has to merge first. beast2 needs no source changes.

Also

• The README links each library in the family list to its repository.
• index.html is removed: it was a leftover redirect, titled "Boost.Buffers", to a doc/html directory that does not exist.

[cppalliance-bot]

An automated preview of the documentation is available at https://455.capy.prtest3.cppalliance.org/index.html

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

2026-10-16 21:54:17 UTC

[cppalliance-bot]

GCOVR code coverage report https://455.capy.prtest3.cppalliance.org/gcovr/index.html
LCOV code coverage report https://455.capy.prtest3.cppalliance.org/genhtml/index.html
Coverage Diff Report https://455.capy.prtest3.cppalliance.org/diff-report/index.html

Build time: 2026-10-16 22:09:55 UTC

[codecov]

Codecov Report

❌ Patch coverage is 98.18182% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 98.45%. Comparing base (43ff48b) to head (85a11dd).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
include/boost/capy/test/bufgrind.hpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #455      +/-   ##
===========================================
+ Coverage    98.33%   98.45%   +0.11%     
===========================================
  Files          137      137              
  Lines         7316     7297      -19     
===========================================
- Hits          7194     7184      -10     
+ Misses         122      113       -9     

Flag	Coverage Δ
linux	98.40% <ø> (+0.25%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
include/boost/capy/detail/abandonable.hpp	100.00% <100.00%> (ø)
include/boost/capy/detail/await_suspend_helper.hpp	100.00% <ø> (ø)
include/boost/capy/detail/results_combinators.hpp	100.00% <100.00%> (ø)
include/boost/capy/ex/abandon.hpp	100.00% <ø> (ø)
include/boost/capy/ex/async_event.hpp	100.00% <100.00%> (ø)
include/boost/capy/ex/async_mutex.hpp	100.00% <100.00%> (ø)
include/boost/capy/ex/async_waker.hpp	100.00% <100.00%> (ø)
...e/boost/capy/ex/context_awaitable_promise_base.hpp	100.00% <100.00%> (ø)
include/boost/capy/ex/frame_alloc_mixin.hpp	100.00% <ø> (ø)
include/boost/capy/ex/frame_allocator.hpp	100.00% <ø> (ø)
... and 20 more

... and 9 files with indirect coverage changes

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