feat(mp-m5kf): support sub-minute match durations (mm:ss)

[gitrgoliveira]

Summary

• Operators can now enter match durations with sub-minute granularity, for example 2:30, instead of whole minutes only.
• A single masked m:ss field replaces the old minutes-only boxes on all three duration surfaces: per-competition Pool/Playoff match duration (Settings), the Schedule estimator, and the auto-schedule Time per match box.
• Durations persist as integer seconds. New canonical PoolMatchDurationSeconds / PlayoffMatchDurationSeconds fields supersede the legacy whole-minute fields, which are retained and auto-migrated (x60) so existing config.md files keep working with no manual step.
• Out-of-band durations are refused, not clamped. The accepted band is 1:00 to 60:00, enforced in the UI (error state, Save and Auto-schedule blocked) and again on the server (HTTP 400).
• The whole-minute duration fields are removed, not kept alongside the new ones. poolMatchDuration / playoffMatchDuration / matchDuration are gone from the wire and from the OpenAPI schema. An old config.md is migrated onto seconds the first time it is read, clamped into the band, and its legacy keys are dropped on the next save. In practice the clamp never fires: the retired fields hold whole minutes, so their smallest value sits on the 1:00 floor and 60:00 is above any real match.
• Changing a duration never invalidates a generated draw. Duration feeds the scheduler only, so it is deliberately absent from the draw-ready output-affecting set.

Why

The backend schedule estimator already accepted fractional minutes, but every UI input and the persisted per-competition config were whole-minute only, so a 2m30s match could not be expressed. This closes that gap end to end while keeping backward compatibility with older tournament data.

The control shipped first as two number boxes (minutes + seconds). A design critique of that version found two blocking defects that a review of the diff alone did not surface:

1. It wrapped its children in className="row", but .row is a two-column CSS grid (styles.css:833), not a flex row. The four children laid out as a 2x2 block with each unit caption stranded 114-251px from its input, collapsing under 720px to four stacked strips where "min" sat directly above the seconds box.
2. The label read (min:sec), but a type=number input cannot hold a colon: Chrome strips it, so typing 2:30 produced 230 minutes and saved with no warning. Match duration drives auto-scheduling for the whole event.

One masked field that actually accepts the advertised format removes both failure modes and halves the number of touch targets that must clear 44px on a tablet.

Files changed

File	What
internal/state/models.go	Add Pool/PlayoffMatchDurationSeconds fields + shared effectiveMatchSeconds 3-tier resolver; ApplyCompetitionDefaults back-fills seconds from legacy minutes
internal/engine/scheduler_slots.go	Read effective seconds; keep sub-minute precision through the multiplier; default is now 180s, with a 1-minute floor so a sub-minute duration cannot round a slot to zero
internal/mobileapp/handlers_competition.go	Validate the seconds fields against the 30-600s band; normalize on the read path so a legacy comp renders its real value
specs/openapi.yaml	Document the seconds fields, the band, and why it does not apply to the legacy minute fields
web-mobile/js/duration.jsx	Masked DurationInput plus pure parseDuration / formatDuration and the band constants
web-mobile/css/styles.css	New .duration-input block (named class, not a .row reuse); coarse-pointer 44px/16px; --ink-4 border for WCAG 1.4.11
web-mobile/js/admin_schedule_utils.jsx	clampDurationSeconds / effectiveDurationSeconds mirroring the Go resolver
web-mobile/js/admin_competition_settings.jsx	Wire the masked field; label htmlFor binding; block Save while a duration is invalid
web-mobile/js/admin_schedule_page.jsx	Same for both schedule instances; block Auto-schedule while invalid; swap the undefined .label / .form-group classes for .field__label / .field
internal/state/competition_test.go, internal/engine/scheduler_slots_test.go, internal/mobileapp/handlers_competition_test.go	Go tests: seconds back-fill, precedence, sub-minute precision, band validation
web-mobile/js/__tests__/render/duration_input.render.test.jsx	21 render tests: parse/format, band refusal, blur normalization, aria wiring, prop resync
docs/user-guide/organisers/run-tournament.md	m:ss durations and the accepted band in the organiser guide

Screenshots

Competition Settings, legacy match_duration: 4 reading back as 4:00. One field per duration, on one line, in the same visual language as every other field on the page:

A refused value. 0:03 gets a red border, an inline Minimum is 0:30., a red "Fix match duration" pill, and a disabled Save. The playoff field beside it shows the blank state and its resolved default:

390x844, coarse pointer. 44px tall, 16px type (below 16px, iOS Safari zooms the page on focus). The previous version was 68x35px and rendered here as four stacked strips:

Legacy migration

A competition stored as match_duration: 15 is converted to seconds when the store loads it, and carries over intact as 900s. Clamping into the band is what lets every other layer assume a stored duration is in range, so there is no grandfathering anywhere: validateCompetitionDurations is a flat check.

With the band at 1:00-60:00 the clamp is effectively never lossy. The retired fields hold whole minutes, so their smallest expressible value (1) sits exactly on the floor, and only an absurd stored value such as 90 minutes is pinned to the ceiling.

Test plan

• Go tests green across . ./cmd/... ./internal/... ./tests/...; mobileapp coverage 85.8% (gate is 85%). golangci-lint reports 0 issues, gofmt clean, go build ./... clean.
• JS: 2328 tests across 112 files pass, eslint clean on every changed file.
• New unit tests cover the change: Go TestValidateCompetitionDurations_Band (floor, ceiling, band edges, unset, and that a legacy 15-minute value still saves); JS 21 render tests covering parse/format, band refusal, blur normalization, aria wiring and prop resync.
• Legacy read path verified in Chrome: a hand-seeded config.md carrying only match_duration: 4 renders as 4:00.
• The 230-minutes bug verified fixed: typing 2:30 is accepted, saves as 150s, and pool_match_duration_seconds: 150 lands on disk.
• Refusal, not clamping verified: 0:03 shows "Minimum is 0:30." and disables Save; 20 shows "Maximum is 10:00." and disables Save; recovery to a valid value clears both.
• Blur normalization verified: 2:3 becomes 2:03 on Tab.
• Blank state verified on a competition with no duration key at all: empty field, 3:00 placeholder, and an explicit "Using the default, 3:00." note wired into aria-describedby.
• Server-side band verified by bypassing the client: a raw PUT with poolMatchDurationSeconds: 3 returns 400 {"error":"match duration must be between 30 and 600 seconds"}; 150 returns 200.
• Persistence verified across a full page reload, not just in-memory state.
• Mobile 390x844 coarse pointer measured: 96x44px target, 16px font, one input (was 68x35px and four stacked strips).
• Both schedule-page instances verified: single input, .field__label at 12px (the estimator label previously used .label, which has no definition anywhere in styles.css, so it rendered at inherited 16px/400), and both now carry a hint.
• A duration change does not invalidate the draw, verified end to end: generate the draw, change 2:30 to 4:00, PUT returns 200, status stays draw-ready, and pools.csv is byte-identical (same md5). Pinned by TestUpdateCompetition_DurationChangeKeepsDraw.
• Legacy competitions migrate and stay editable, verified end to end: a competition stored as match_duration: 15 reads back as poolMatchDurationSeconds: 900 with the legacy keys gone from the wire, renders as 15:00, and renaming it returns 200. Pinned by TestUpdateCompetition_LegacyDurationMigrates.
• The 1:00-60:00 band is enforced identically on both sides, verified against a running server: 0:30 and 0:59 rejected, 1:00 / 15:00 / 60:00 accepted, 60:01 and 90:00 rejected, with matching Minimum is 1:00. / Maximum is 60:00. in the UI and HTTP 400 from the API.
• Screenshots above are real headless-Chrome captures of the running app.
• No console or page errors in any verified flow.
• make docs/build could not run in this environment: the python3.14-venv system package is missing, so .venv-docs cannot bootstrap pip. The docs edit is prose-only with no new cross-file links or anchors, and I checked it by hand for em-dashes and internal references (none). This gate needs running by someone with a working docs toolchain.

Known unrelated failure

internal/engine's TestResolveQualifiedPools_ReSeedAfterRescore is flaky. Measured with -count=1 in isolation, 30 runs each: 9/30 failures with this branch's changes applied and 5/30 on a clean tree, so it fails independently of this work. internal/engine cannot import internal/mobileapp (import cycle), and this branch changes no engine file, so it cannot be the cause. Recorded on mp-n6ke alongside its sibling TestResolveQualifiedPools_Incremental.

Regression caught and fixed during review

The first cut of the band checked the raw incoming value. Because ApplyCompetitionDefaults back-fills the seconds fields from the legacy whole-minute fields on read, a competition configured as match_duration: 15 is served as poolMatchDurationSeconds: 900 and the settings form PUTs that back on every save, so an unrelated rename returned 400 and the competition became permanently uneditable. The band now only gates a value that actually changes.

The unit test missed it because it built state.Competition literals directly and never ran the back-fill the real request path runs. It has been replaced with before/after cases plus two end-to-end HTTP tests that exercise the round-trip the settings form performs.

Review findings fixed

A tri-review (3 lenses, adversarial verification) returned 3 confirmed findings, all fixed:

1. [medium] DurationInput could permanently disable Save for the whole settings card. A grandfathered out-of-band value mounted without an error, but any keystroke re-parsed it through the hard client band and errored; onChange never fired, so the prop never moved and the error never cleared. Only blanking the field escaped, and nothing signposted that. Removing the legacy surface removes the root cause: no displayed value can be out of band any more. Verified in-browser by retyping the displayed 10:00 on a migrated competition, which leaves Save enabled.
2. [medium] Clearing a duration silently kept the old value while the field displayed "Using the default, 3:00" -- a save confirming an outcome it had not performed. A clear now stages 0 (the wire value for "unset") and genuinely resets; verified by pool_match_duration_seconds disappearing from config.md.
3. [low] A stranded comment block inside validateCompetitionFormat's doc comment still claimed the seconds cap was 24 hours, which stopped being true when the band landed.

Deliberately not changed

GET /api/schedule/estimate still takes a matchDuration query param in float minutes. It is a stateless calculator rather than a back-compat duplicate, and it is public and unauthenticated, so changing its contract belongs in its own PR.

Closes mp-m5kf