Read cylinder end pressure at surfacing, not at the end of the recording

[ericgriffin]

Dive computers keep recording for a few minutes after the diver reaches the
surface. On a rebreather whose oxygen cylinder feeds a constant mass flow
orifice, closing the valve topside leaves the hose bleeding down through that
orifice, and the tail of the recording sheds most of the cylinder's apparent
contents. The reporter's dive read 41 bar of oxygen at 1.2 m and 4 bar two
minutes later on the surface, so the import logged 4 bar and overstated his
oxygen consumption roughly tenfold.

The cause is upstream of us and structural. libdivecomputer's
shearwater_predator_parser.c builds DC_FIELD_TANK's end pressure by
overwriting it with every pressure sample as it walks the log, with no
surfacing check, so it lands on the last sample in the tail. Both it and
sample.pressure.value use the identical pressure * 2 * PSI / BAR expression
on the same raw value, so the reported end pressure is bit-identical to the
last sample emitted.

The rule

lib/core/profile/surfacing_pressure.dart finds the last sample deeper than
0.75 m (Subsurface's SURFACE_THRESHOLD, so both apps agree on where a
dive ended) and reads each cylinder's most recent pressure at or before that
moment. A diver who drops back down after a surface break is measured from the
final descent, and each cylinder carries its own last value forward because
transmitters report on their own cadence.

It corrects a reported end pressure only when that value matches the last
post-surfacing reading. That match is the evidence the source simply took the
last sample it had. Three things follow from it:

• A parser that reads end pressure from a log header rather than the sample
  stream (Suunto, Uwatec) is left alone, because its value has an origin this
  rule knows nothing about.
• A transmitter that dropped out before the diver surfaced never triggers a
  correction, so a stale in-water reading cannot be promoted over a real end
  pressure.
• Exported files whose end pressure the source app computed itself keep that
  value, rather than being silently overridden by ours.

Beyond that the correction only ever raises a value, and a source that reported
no end pressure keeps reporting none rather than gaining a fabricated one.

Where it applies

• Dive computer download and reparse share resolveParsedTanks, so both
  paths get it from one seam. Reparse matters here: an already-imported dive is
  corrected with Reparse raw data on the dive detail menu, with no need to
  re-download from the computer.
• Every file format converges on one payload shape (tanks with
  endPressure, profile points with allTankPressures), so a single
  post-parse normalizer covers FIT, UDDF, DL7, Subsurface, Ratio, MacDive and
  Shearwater Cloud. It runs after the parsers, which keeps
  FitTankExtractor's cylinder-volume derivation on the start/end pair Garmin
  actually reported.

Setting

diver_settings.trim_tank_pressure_at_surfacing, schema v165, default
on. Main reserved that number while this branch was open, so the ladder
needed no renumbering when main went on to v168. It appears in Settings > Data beneath Site
Matching, the other import-interpretation preference, and is translated across
all 11 locales.

Not doing

The profile itself is untouched: the post-surfacing tail stays on the chart,
honest about what the computer recorded. Start pressure is unchanged, the
threshold is not configurable, and already-imported file dives are not
retroactively repaired (only dive computer dives, via reparse).

Closes #1092

[Copilot]

Pull request overview

Implements a “tank pressure at surfacing” correction so end cylinder pressure is taken from the last in-water reading (deeper than 0.75 m) instead of the final post-surfacing tail sample, addressing dive computers that keep recording topside and can dramatically understate remaining pressure (Issue #1092). The change is applied across both dive-computer downloads/reparse and universal file imports, gated by a new persisted diver setting (default on) and exposed in Settings > Data.

Changes:

• Add core surfacing-pressure logic (surfacingTankReadings + trimEndPressureBar) and apply it to dive-computer tank resolution and universal-import payload normalization.
• Introduce trim_tank_pressure_at_surfacing (schema v163) with UI toggle + localization across all supported locales.
• Add targeted unit/integration tests covering the core rule, persistence/migration, download/reparse behavior, and universal import end-to-end.

Reviewed changes

Copilot reviewed 49 out of 49 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/helpers/mock_providers.dart	Adds mock SettingsNotifier support for the new toggle setter.
test/features/universal_import/presentation/providers/universal_import_surfacing_pressure_test.dart	End-to-end test proving the rule is reached during real file import and respects the setting.
test/features/universal_import/data/services/surfacing_pressure_normalizer_test.dart	Unit tests for payload-level end-pressure normalization behavior and immutability.
test/features/statistics/presentation/pages/records_page_test.dart	Updates local mock settings notifier for the new setter.
test/features/settings/presentation/pages/settings_page_test.dart	Updates local mock settings notifier for the new setter.
test/features/settings/presentation/pages/settings_page_surfacing_pressure_test.dart	Widget tests for the Settings > Data toggle default and persistence via notifier.
test/features/settings/presentation/pages/settings_page_shared_data_test.dart	Updates local mock settings notifier for the new setter.
test/features/settings/data/repositories/diver_settings_repository_surfacing_pressure_test.dart	Verifies new setting defaults to true and round-trips through repository updates.
test/features/dive_computer/presentation/providers/download_notifier_surfacing_test.dart	Ensures live download applies the setting at dive-arrival time.
test/features/dive_computer/data/services/reparse_service_surfacing_test.dart	Ensures reparse honors the setting and stores the corrected end pressure.
test/features/dive_computer/data/services/parsed_tank_resolver_surfacing_test.dart	Unit tests for libdivecomputer tank resolution with surfacing trimming and edge cases.
test/features/dive_computer/data/services/parsed_dive_mapper_test.dart	Adds coverage that downloaded mapping trims by default and supports opt-out.
test/core/profile/surfacing_pressure_test.dart	Comprehensive unit tests for surfacing-point selection and end-pressure trimming semantics.
test/core/database/migration_v163_surfacing_pressure_test.dart	Tests migration adds the new column with default=on and is present on fresh DBs.
lib/l10n/arb/app_en.arb	Adds title/subtitle strings for the new settings toggle (English).
lib/l10n/arb/app_de.arb	Adds German strings for the new settings toggle.
lib/l10n/arb/app_es.arb	Adds Spanish strings for the new settings toggle.
lib/l10n/arb/app_fr.arb	Adds French strings for the new settings toggle.
lib/l10n/arb/app_it.arb	Adds Italian strings for the new settings toggle.
lib/l10n/arb/app_pt.arb	Adds Portuguese strings for the new settings toggle.
lib/l10n/arb/app_nl.arb	Adds Dutch strings for the new settings toggle.
lib/l10n/arb/app_hu.arb	Adds Hungarian strings for the new settings toggle.
lib/l10n/arb/app_he.arb	Adds Hebrew strings for the new settings toggle.
lib/l10n/arb/app_ar.arb	Adds Arabic strings for the new settings toggle.
lib/l10n/arb/app_zh.arb	Adds Chinese strings for the new settings toggle.
lib/l10n/arb/app_localizations.dart	Generated localization API additions for new keys.
lib/l10n/arb/app_localizations_en.dart	Generated English localization implementation updates.
lib/l10n/arb/app_localizations_de.dart	Generated German localization implementation updates.
lib/l10n/arb/app_localizations_es.dart	Generated Spanish localization implementation updates.
lib/l10n/arb/app_localizations_fr.dart	Generated French localization implementation updates.
lib/l10n/arb/app_localizations_it.dart	Generated Italian localization implementation updates.
lib/l10n/arb/app_localizations_pt.dart	Generated Portuguese localization implementation updates.
lib/l10n/arb/app_localizations_nl.dart	Generated Dutch localization implementation updates.
lib/l10n/arb/app_localizations_hu.dart	Generated Hungarian localization implementation updates.
lib/l10n/arb/app_localizations_he.dart	Generated Hebrew localization implementation updates.
lib/l10n/arb/app_localizations_ar.dart	Generated Arabic localization implementation updates.
lib/l10n/arb/app_localizations_zh.dart	Generated Chinese localization implementation updates.
lib/features/universal_import/presentation/providers/universal_import_providers.dart	Applies surfacing-pressure normalization to completed import payloads, gated by setting.
lib/features/universal_import/data/services/surfacing_pressure_normalizer.dart	Implements payload-level end-pressure rewrite using the core surfacing rule.
lib/features/settings/presentation/providers/settings_providers.dart	Adds trimTankPressureAtSurfacing to AppSettings + notifier setter + default true.
lib/features/settings/presentation/pages/settings_page.dart	Adds Settings > Data switch for “Tank pressure at surfacing”.
lib/features/settings/data/repositories/diver_settings_repository.dart	Persists/loads the new setting in DiverSettingsRepository.
lib/features/dive_computer/presentation/providers/reparse_providers.dart	Wires current setting into ReparseService provider so reparses respect updates.
lib/features/dive_computer/presentation/providers/download_providers.dart	Reads setting at dive-arrival time to avoid tearing down active downloads.
lib/features/dive_computer/data/services/reparse_service.dart	Propagates the setting to parsed tank resolution during reparse updates.
lib/features/dive_computer/data/services/parsed_tank_resolver.dart	Adds surfacing trimming to tank resolution while keeping gas-switch derivation unchanged.
lib/features/dive_computer/data/services/parsed_dive_mapper.dart	Adds opt-out parameter and defaults to trimming for downloaded dive mapping.
lib/core/profile/surfacing_pressure.dart	New core surfacing-pressure rule implementation (threshold + matching tolerance + trim).
lib/core/database/database.dart	Adds diver_settings column + v163 migration/backstop and bumps schema version.

---

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[codecov]

Codecov Report

❌ Patch coverage is 94.89051% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ngs/presentation/providers/settings_providers.dart	25.00%	3 Missing ⚠️
lib/core/database/database.dart	84.61%	2 Missing ⚠️
...ter/presentation/providers/download_providers.dart	60.00%	2 Missing ⚠️

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[github-actions]

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[Copilot]

Pull request overview

Copilot reviewed 49 out of 49 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 49 out of 49 changed files in this pull request and generated no new comments.

Suppressed comments (1)

lib/core/database/database.dart:3189

• PR description says the diver_settings setting is schema v163 (with v162 claimed by #1269), but the migration ladder and currentSchemaVersion here are v165. Please update the PR description (and any linked docs) to match the actual schema version to avoid confusion when backporting or tracking migrations.

  /// The current schema version as a static constant so that pre-open checks
  /// (e.g. version-mismatch guard) can reference it without an instance.
  static const int currentSchemaVersion = 165;

  /// The oldest schema whose reader can apply this build's sync payloads

[Copilot]

Pull request overview

Copilot reviewed 49 out of 49 changed files in this pull request and generated 1 comment.

Suppressed comments (1)

lib/core/database/database.dart:3188

• PR description says the diver setting is schema v163, but this change bumps the DB schema to v165 (including migration ladder and tests). Please update the PR description (or any linked docs/release notes) to reflect v165 so schema references stay consistent.

  /// The current schema version as a static constant so that pre-open checks
  /// (e.g. version-mismatch guard) can reference it without an instance.
  static const int currentSchemaVersion = 165;

[Copilot]

Pull request overview

Copilot reviewed 49 out of 49 changed files in this pull request and generated no new comments.

[ericgriffin]

Flagging something found while clearing the merge conflicts across the other open PRs. This PR has no conflict, but its migration rung is now dead.

main is at v170 (it took v168 from #638 and v170 from #1322). This branch's currentSchemaVersion is 168, and its new step is at v165:

// v165: trim_tank_pressure_at_surfacing on diver_settings (#1092).
if (from < 165) {
  await _assertSurfacingPressureColumn();
}

Because only main moved the scalar since this branch last merged, git will resolve it silently to 170 with no conflict marker. The result is a build that reports schema 170 while its v165 step can never fire: every existing database is already at 168 or 170, so from < 165 is false and _assertSurfacingPressureColumn() is skipped on upgrade.

The beforeOpen backstop does still call it, so the column will exist and this will not throw. That is exactly what makes it easy to miss: it looks fine, and the rung is simply inert.

Suggested fix, matching what the other overtaken PRs were moved to in this pass: renumber v165 to v176 (171 #1319, 172 #1328, 173 #1276, 174 #603, 175 #1320 are all claimed), leaving 165 permanently skipped, and update any migration_v165_* test filename and its contains(165) / greaterThanOrEqualTo(165) tripwires.

I have not touched this branch, since it has no conflict to resolve. Happy to push the renumber if you want it.

For reference, the ladder after this pass: main 170; 171 #1319; 172 #1328; 173 #1276; 174 #603; 175 #1320; next free 176. 138, 162, 167 and 169 are permanently skipped.