feat(ladder): preserve tranche amount provenance

[cristim]

Persist a nullable amount basis and exact planning rate through tranche insertion, due-claim reads and fired reconciliation. The current OD writer records its verified basis explicitly. Historical rows retain unknown metadata and their original amounts, with no backfill or default.

Migration 121 follows current main's 120. This leaf keeps the existing SDK pins and scalar planner; it does not activate native-unit allocation.

Verification at 1c351b3 (tree 01633c9970987c31d47c350e322f25d61f2923ee): two retained independent source passes and two fresh independent committed verification passes found no actionable findings. Native PostgreSQL 17.11 exercised migration up/down/up, insert-to-claim-to-reconcile, invalid batch rollback and invalid persisted rates using synthetic records. Parent and semantic mutation probes failed at intended runtime assertions. Affected race suites, full backend build, pinned golangci-lint 2.10.1 and all normal commit hooks passed. No live provider operations were performed.

Closes #885

Summary by CodeRabbit

• New Features
  • Ladder tranches now record whether their amount is based on an on-demand equivalent or a commitment, including the applicable commitment rate.
  • Existing tranches without verified amount details remain supported, and saved provenance is available when tranches are claimed or listed.
• Bug Fixes
  • Invalid or inconsistent commitment details are rejected when saving or retrieving tranches, helping prevent incorrect tranche data from being returned.

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📥 Commits

Reviewing files that changed from the base of the PR and between 1c351b3 and 06f973a.

📒 Files selected for processing: 4

• internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance.up.sql
• internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance_test.go
• internal/database/postgres/migrations/000122_validate_ladder_tranche_amount_provenance.down.sql
• internal/database/postgres/migrations/000122_validate_ladder_tranche_amount_provenance.up.sql

📝 Walkthrough

Ladder tranches now store optional amount-basis and commitment-rate provenance. The current on-demand writer sets the basis explicitly. Insert, claim, and reconciliation paths persist and validate the provenance.

Changes: Ladder tranche provenance

Layer / File(s)	Summary
Provenance model and schema internal/config/types.go, internal/config/ladder_provenance.go, internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance.*.sql, internal/config/types_test.go, internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance_test.go	LadderTrancheDB adds optional amount-basis and commitment-rate fields. The migration adds nullable columns and restricts valid basis/rate combinations. Tests cover JSON representation and migration behavior.
Set and persist provenance on tranche creation internal/server/handler_ladder.go, internal/config/store_postgres_ladder.go, internal/server/handler_ladder_test.go	The current writer sets the on-demand-equivalent basis. Tranche insertion derives and stores a commitment rate when applicable, and the handler test checks the serialized provenance.
Read and validate tranche provenance internal/config/store_postgres_ladder_lifecycle.go, internal/config/store_postgres_ladder_reconcile.go, internal/config/store_postgres_ladder_test.go	Due-tranche selection and fired-tranche listing read and validate provenance. The PostgreSQL integration test covers insertion, claiming, reconciliation, and rollback for invalid provenance.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Feature

Merge Risk: 🟡 Moderate · up to 1c351

On a large tranche table, deploying this migration could interrupt tranche access. Separate constraint creation and validation before merging, or explicitly accept that deployment risk.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 10 files. (2 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: preserving tranche amount provenance.
Linked Issues check		Issue #885 is directly linked and has coding requirements. The PR adds nullable AmountBasis and CommitmentRate fields, validates basis/rate pairs, persists them through insertion, due-tranche clai…
Out of Scope Changes check		The changed production files, migrations, and tests directly support issue #885. The changes add provenance types, validation, persistence, lifecycle reads, migration behavior, and regression coverage…

Full details: Docstring Coverage

Explanation

Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 10 files. (2 skipped: 2 unsupported.)

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Actionable comments posted: 1

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Inline comments:
Review comments at
@internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance.up.sql:
- Line 5: Mark the CHECK constraint added by the ladder tranche amount
provenance migration as NOT VALID, then add a separate later migration that
validates ladder_tranche_amount_provenance after the initial migration
transaction commits.

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📥 Commits

Reviewing files that changed from the base of the PR and between 842ec35 and 1c351b3.

📒 Files selected for processing: 12

• internal/config/ladder_provenance.go
• internal/config/store_postgres_ladder.go
• internal/config/store_postgres_ladder_lifecycle.go
• internal/config/store_postgres_ladder_reconcile.go
• internal/config/store_postgres_ladder_test.go
• internal/config/types.go
• internal/config/types_test.go
• internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance.down.sql
• internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance.up.sql
• internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance_test.go
• internal/server/handler_ladder.go
• internal/server/handler_ladder_test.go

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[cristim]

Resolved in 06f973a (tree 8697541de5b65b653dee87bfb23b8386c520cadc).

Migration 121 now adds the unchanged CHECK as NOT VALID. Migration 122 validates it in a separate committed transaction; rollback restores the identical NOT VALID constraint atomically. No data backfill, default or amount change.

Independent PostgreSQL 17.11 fixture evidence confirmed the original ACCESS EXCLUSIVE lock blocks ordinary updates; validation in the separate transaction holds SHARE UPDATE EXCLUSIVE and permits ordinary insert/update/delete. This used a minimal synthetic table and observed DML after the validation statement, not a timed production scan. The committed native regression verifies false→true→false validation states, continued new-write enforcement, rollback to 120 with preserved amounts, and ordered re-upgrade with historical NULL metadata.

Two retained independent source passes and two independent committed verification passes found no actionable findings at this exact revision. Parent SQL and a scratch SELECT 1 replacement for validation each produced the intended runtime assertion failure; restored code passed. Independent rollback-failure atomicity, affected race suites, backend build, pinned lint and all normal hooks passed. Existing unaffected provenance evidence transfers after exact byte comparison.

The docstring coverage warning is not adopted: the new internal validator is directly named and its contract is exercised; adding comments to untouched helpers would expand this focused change. Required CI will be checked at this new SHA before normal merge. This remains provenance-only; the existing allocator and SDK pins are unchanged.

[cristim]

Merged in #886 as 282c7e1.

Verified: nullable provenance and exact stored-rate round trips passed through actual PostgreSQL insert, due-claim and fired reconciliation. Ordered migrations 120→121→122→121→120→122 preserve amounts and historical unknowns; validation states and continued write enforcement passed. Independent parent and mutation probes failed at intended assertions. The affected merged source and module pins are byte-identical to the independently verified revision.

Post-main CI 38731227754, pre-commit 38731227794, frontend 38731227745 and deployment 38731227859 completed successfully. The CI-produced dev deployment artifact records both commit and image tag as 282c7e1, and its deployment test passed. PostgreSQL evidence uses owned synthetic fixtures; no live provider purchase or live database migration inspection was performed.

This completes the provenance leaf. Allocator adoption remains tracked in #631; this PR keeps the existing allocator and SDK pins unchanged.