Status: LOCAL_DONE on codex/phase-12-kmp-foundation (phase PR #21, draft). Issue: #17. Dependency P12-T01 LOCAL_DONE satisfied. No behavior change to existing screens; no KMP Gradle plugin added yet (deferred to P12-T03 by design, per the frozen T01 rollback baseline).

Frozen contract, owned downstream: B-BR-002 exact money (Go kernel parity), F03 280-scalar comments (P14), A04/B-BR-A04 identity shape (P13), M/L time and risk inputs (P15/P16). This task introduces the portable kernel and golden vectors; endpoint/schema/DB work stays in owning phases.

Portable-ready pure Kotlin in :domain (package com.anpfuel.domain.portable, zero java.* imports, guard-tested so the files move unchanged to commonMain later). com.anpfuel packages and MIT notices preserved.

• PortableMoney.kt — integer milli-BRL, ANP comma grammar, range 1..1000000, over-precision refusal (never rounding), canonical "<int>,<3dp>" format, capacity in milli-liters (1..200000) and overflow-checked half-up tank-fill multiply. Mirrors backend/internal/modules/kernel/price.go case-for-case, including the padded/negative-zero/zero branches.
• PortableText.kt — trim + CRLF normalization, surrogate-aware Unicode scalar counting (astral emoji = 1, combining sequence = base + mark, same as Go rune count), 280-scalar validity (F03).
• PortableIdTime.kt — lowercase canonical UUID and strict UTC YYYY-MM-DDTHH:MM:SSZ with leap-year calendar checks. No java.util.UUID/java.time in portable code.
• contracts/testdata/compat/money-portable-v1.json — canonical golden vectors (money valid/invalid + quarantine codes, tank-fill totals, text, UUID and instant cases) with provenance at base 6f4f048.
• Tests: PortableMoneyTest (11), PortableTextTest (7), PortableIdTimeTest (5), PortableParityTest (7) — 30 new tests.

Existing calculators are untouched; they migrate to portable math in P12-T03. The parity test asserts both the agreements and the divergences above, so no drift can enter silently.

./gradlew :domain:test :application:test --rerun-tasks --no-daemon
./gradlew :data:testDebugUnitTest :app:testDebugUnitTest --no-daemon
./gradlew :app:assembleDebug --no-daemon
cd backend && go test ./internal/modules/kernel/...
make quick-verify
git diff --check

Outcome:

• :domain + :application: all suites pass including 30 new portable tests, 0 failures (full counts recorded in commit evidence).
• :data + :app unit tests and assembleDebug: SUCCESS (no Android source touched; regression only).
• Backend kernel package: PASS (no Go source touched; parity reference).
• make quick-verify: ok; git diff --check clean; secrets scan clean.
• Delivery fix in this commit: scripts/quick-verify.sh selection now classifies P12 mobile areas (domain/, application/, data/, app/, gradle/, shared/, iosApp/, root Gradle manifests) into the full set instead of refusing them as unclassified; test-gate harness 10/10. Android behavioral evidence stays at task level + phase exit until P12-T05 adds bounded KMP/iOS check selection.

• No commonMain source set, no KMP Gradle plugin, no Swift framework yet; that assembly is P12-T03/P12-T04 on top of this contract.
• iOS/Swift parity against the JSON vectors is asserted by fixture presence, not by a Swift run; macOS evidence belongs to P12-T04/T05.
• Instrumentation (connectedDebugAndroidTest) and performance budgets stay deferred to P12-T05/P18.

P12-T03 application ports and offline state (#18): pure common use-case state on top of this kernel, Room kept as Android adapter. Issue #17 stays open until the P12 phase PR merges.