[Alexandru Dima (alexdima)]

Follow-up to #342907.

What

ripple plan had a cost-based cutoff: when the selected unit tests were more than --max-share (default 0.5) of the unit test work, it reported running every unit test: the change affects N% of the unit test work (limit 50%) and set select: false, so macOS and Windows ran every unit test. This removes it, without a replacement threshold. A plan now either selects exactly the unit test files that a change can affect, however many, or runs every unit test for a dependency reason only (Selection::run_all): a runEverything file, a package or script of the test runners, a module that the runners use, or a module that does not parse. Linux still runs every unit test on every push.

• build/ripple/src/main.rs: --max-share is gone from the usage, the option list and the parsing (passing it now fails with unknown option '--max-share'), and so are the max_share parameter of plan() and its reason. select is sel.run_all.is_none(). share stays in plan.json and in the reason of a selection, as information. rustfmt now packs OPTIONS onto two lines: "max-share" was its only element longer than rustfmt's threshold for short array elements (10 characters).
• build/ripple/README.md: the CI paragraph and the plan command no longer mention the limit.

pr.yml never passed --max-share and needs no change: its Check ripple step reads .reason only for parse error (, and .select and .unit for a plan that selects nothing.

What the limit cost

On the replay of the 708 first-parent commits of main from Oct 13 to 20 (the one in the README), 18 commits (2.5%) went over the limit. They would have selected 69.6% of the unit test work on average, and ran all of it. Without the limit, the macOS and Windows unit test work per commit drops from 9.8% to 9.0% of a full run on average, about 0.4 VM minutes per push: the unit test steps of a full run took 49.4 VM minutes on macOS and Windows in the last run of #344104, which ran every unit test.

Open pull requests that read plan.json

Neither depends on the limit's reason text:

• ci: skip macOS and Windows Browser unit jobs without browser tests, and report a failed ripple plan #344108 (ripple/skip-browser-jobs) reads .reason only for parse error (, and .select and .unit. It rewrites the same README sentence and keeps "or when it affects more than half of the unit test work", so whichever of the two merges second has a one-line conflict there: drop that clause.
• ci: warn about Linux unit test failures that the unit test plan did not select #344106 (ripple/recall-warning) reads .select and unit.txt. The plans that went over the limit now select, so its recall check covers them too.

Validation

• cd build/ripple && cargo +nightly-2026-04-14 fmt && cargo test --release --locked && cargo build --release --locked: passed. rustfmt's only change is the OPTIONS layout above; 72 tests passed; the release build has no warnings.
• The 18 commits that went over the limit now select. For each commit of the replay with decl > 0.5 and runAll == null: ripple plan --config build/ripple/vscode.jsonc --base <sha>^1 --head <sha>, with this branch's binary and with the one built from a383e08 (ci: run only the unit tests a change can affect on macOS and Windows #342907), which has the limit. This branch selects in all 18, exactly the replay's declTestFiles, and both binaries list identical files (.unit). The replay predates ripple: count writes to pure globals as load-time effects #344104, but ripple: count writes to pure globals as load-time effects #344104 changes none of these selections: its own replay found all 708 commits identical on declTestFiles and runAll. The shares match up to the rounding of share to 4 decimals in plan.json (largest difference 0.00005).

The 18 commits

Pull request	Commit	Share	Replay: declTestFiles	This branch	main at a383e08
#341342	0695d91	76.2%	1,525	select: true, 1,525 files	select: false (limit 50%)
#341406	50559e7	59.6%	1,083	select: true, 1,083 files	select: false (limit 50%)
#341434	425e631	67.6%	1,383	select: true, 1,383 files	select: false (limit 50%)
#341208	d548c2a	63.8%	1,188	select: true, 1,188 files	select: false (limit 50%)
#341463	cf0ccf5	67.8%	1,398	select: true, 1,398 files	select: false (limit 50%)
#341674	8734ece	67.8%	1,401	select: true, 1,401 files	select: false (limit 50%)
#341640	54d466a	67.5%	1,396	select: true, 1,396 files	select: false (limit 50%)
#334259	922ce6a	83.9%	1,820	select: true, 1,820 files	select: false (limit 50%)
#341861	009603b	67.8%	1,414	select: true, 1,414 files	select: false (limit 50%)
#340669	0b4e063	66.2%	1,276	select: true, 1,276 files	select: false (limit 50%)
#341922	be4f9ba	67.5%	1,418	select: true, 1,418 files	select: false (limit 50%)
#341965	c35fcfc	67.6%	1,420	select: true, 1,420 files	select: false (limit 50%)
#342210	e630a74	67.5%	1,426	select: true, 1,426 files	select: false (limit 50%)
#342485	91065a6	67.2%	1,428	select: true, 1,428 files	select: false (limit 50%)
#342681	1155fd0	67.2%	1,428	select: true, 1,428 files	select: false (limit 50%)
#342688	23794cf	81.4%	1,828	select: true, 1,828 files	select: false (limit 50%)
#342941	d1ce11c	67.3%	1,437	select: true, 1,437 files	select: false (limit 50%)
#342960	2c225c3	78.8%	1,745	select: true, 1,745 files	select: false (limit 50%)

• The 16 commits that run everything still do: select: false, with the replay's runAll reason (12 test job definitions, 2 test runners, 1 transpiler, 1 runtime version).
• The CI path, for the commit of fix: path, URI, JSON edit utility bugs #334259 (83.9%), with --out-dir, GITHUB_OUTPUT and GITHUB_STEP_SUMMARY: select=true, a unit.txt with 1,820 files, and a job summary that lists them. The Check ripple expressions of pr.yml on that plan.json: no parse warning, selects-nothing=false.
• ripple plan --config vscode.jsonc --base HEAD --max-share 0.5: Error: unknown option '--max-share'.
• git grep -nE 'max-share|max_share|half of the unit test|limit 50|\(limit ' -- build/ripple .github test/unit build/lib: no matches.
• node --experimental-strip-types build/hygiene.ts build/ripple/src/main.rs build/ripple/README.md: passed (it checks main.rs; README.md is not eligible). The pre-commit hook passed too.
• Not run locally: the workflows. Since this changes build/ripple, its CI runs every unit test, and the Ripple check builds, tests and plans with this branch.

[Copilot]

🟢 Approval recommended

The focused removal matches the intended behavior, preserves existing plan contracts and dependency safeguards, and has no unresolved findings.

No open issues 🎉

What changed in this PR

Removes Ripple’s cost-based cutoff so macOS and Windows CI use affected unit test selections regardless of their share of total test work.

Changes:

• Removes --max-share and the 50% fallback; dependency-based full-run safeguards remain.
• Preserves share as informational output and leaves Linux full-test runs unchanged.
• Updates CLI help and documentation to match the new behavior.

File	Description
build/​ripple/​src/​main.rs	Removes threshold parsing and makes selection depend only on run_all.
build/​ripple/​README.md	Documents unrestricted selection and removes the obsolete option.

_{Review effort: Balanced}