[dzid26]

Summary

Closes #114

chargeSessions() paired the SOC swing between the first and last charging samples the app saw with charge_energy_added / charge_miles_added_rated, which the car reports as running totals since its session began. A session first seen mid-charge (app opened late, link dropped, phone away) therefore over-estimated capacity and full range: plug-in at 20 %, first sample at 50 % with 22.5 kWh, last at 80 % with 45 kWh read as 45 / 30 % = 150 kWh instead of 75 kWh. The rated-miles backbone was inflated the same way.

• Deltas. Energy and rated miles are the growth of each counter from the first to the last sample of a session (last - first). A null first value counts as 0. A counter that goes down inside a session was restarted by the car (for example a stale total on a Starting sample), so the last value is used. The existing > 0 checks stay.
• Segmentation (documented in the KDoc of chargeSessions()): a session is a run of Charging/Starting samples; a Stopped/NoPower pause shorter than 10 minutes (last charging sample to the resuming one) does not end it; Complete, Disconnected, any other state (missing, Unknown, Calibrating) or a longer pause does. Blips no longer inflate the count behind the learning gate.
• Moved to core. ChargeSession and chargeSessions() now live in core/.../health/ChargeSession.kt (with MIN_SWING_PERCENT); healthSummary() imports them. BatterySample is untouched. The file is ChargeSession.kt, not ChargeSessions.kt, because detekt's MatchingDeclarationName requires a file with one top-level class to be named after it.
• Comment fix. The comment above LEARNING_SESSIONS = 3 described the twenty sessions of HIGH_SESSIONS. It now describes the three; the twenty-session sentence moved to HIGH_SESSIONS. Value unchanged.
• Test dependency. core/build.gradle.kts adds testImplementation(kotlin("test")): ADR-0007 asks new core tests to use kotlin.test, and the new tests do. Existing JUnit tests are unchanged.

Judgment calls worth a look:

• Silence is not a pause. Two charging samples with nothing between them (link dropped) stay one session however far apart; only Stopped/NoPower samples can start the 10-minute clock. The counters are cumulative, so the delta covers the unobserved stretch.
• A counter restart is any decrease between consecutive non-null readings, not just last < first, so a stale first value that the new session climbs back past is still caught.

Type

• Bug fix
• Feature
• Protocol / crypto change
• Docs / CI / tooling
• Refactor (no behavior change)

Testing

• ./gradlew :core:test: run as a core-only scratch build, because Google Maven is unreachable here and the app modules cannot be built. :core:test, :core:ktlintCheck and :core:detekt pass (135 tests, 17 of them new in ChargeSessionsTest: mid-charge capacity 75 kWh not 150, counter reset, Starting then Charging, short Stopped blip, long Stopped gap, Complete, Disconnected, and more).
• Mutation check in the scratch copy: reverting each rule (cumulative last value, no reset detection, no pause bridging, Starting excluded, > instead of >= at the 10-minute boundary, ...) fails at least one new test.
• ./gradlew :app:testDebugUnitTest: not run. Instead the changed HealthSummary.kt and the unchanged HealthSummaryTest.kt were copied into the scratch core project (scratch only) and compiled, linted and run against the new core code: 6/6 pass. CI still has to compile the app.
• ./gradlew :app:lintDebug: not run (see above)
• Real car: not tested

Checklist

• Protocol changes ship test vectors; expected.txt regenerated, not hand-edited (n/a: no protocol change)
• No VINs, keys, or decrypted payloads in logs
• Docs/master-plan updated where relevant (not touched: Replace the history CSV with an append-only raw ChargeState log #94 edits docs/master-plan.md, and the "Battery health v1" item stays open)
• New source files carry SPDX-License-Identifier: AGPL-3.0-only

🤖 Generated with Claude Code

https://claude.ai/code/session_0129RzhbEE2cboMcYyZMuxqX

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Screenshots

Captured from the demo build at 1bd232d.