fix(api): scale pool usage snapshot limits by pool member count (summed budget)

[dpozimski]

Problem

GET /api/quota/pools/[id]/usage passes the provider plan's per-account dimensions straight to poolUsageWithDimensions, while enforce.ts multiplies every dimension limit by the pool's member-connection count before deciding anything (the summed budget). For a multi-connection pool the snapshot therefore reports limits and fair shares N times smaller than what enforcement actually uses.

I hit this in production today: a 27-connection pool with a usd/daily plan limit of 66.67 (enforced budget 1800.09) had consumed 54.09. The Quota Share page showed 81% utilisation; real utilisation was 3%. The per-key borrowing flags have the same problem: they trip once a key crosses weight% of the per-account limit instead of weight% of the summed budget, so on that pool they fire 27x too early.

Fix

Scale the resolved plan dimensions by accountCount in the usage route before calling the store, using the same computation and legacy fallback as enforce.ts (connectionIds.length, falling back to 1 when the array is missing or empty). Snapshot limit, fairShare, deficit and borrowing then all describe the budget that is enforced. Single-connection and legacy pools are unchanged (N=1), and the { usage: snapshot } wrapper contract is untouched.

Scaling at the route level covers both store drivers, since sqlite and redis both receive their dimensions from this one caller.

Tests

Added tests/unit/quota-pool-usage-summed-budget.test.ts, following the pattern of quota-summed-budget.test.ts (which pins the same multiply on the enforcement side) and quota-pool-usage-shape.test.ts: structural assertions that the route applies the multiply with the right fallback, plus a logic-level check that the scaled limit corrects fairShare and borrowing for the 27-connection case above.

Ran locally:

node --import tsx/esm --test tests/unit/quota-pool-usage-summed-budget.test.ts \
  tests/unit/quota-pool-usage-shape.test.ts \
  tests/unit/quota-summed-budget.test.ts \
  tests/unit/quota-sharing-fixes.test.ts
# 23 pass, 0 fail

npm run lint (scoped to the two changed files) is clean.

[dpozimski]

hi @diegosouzapw , would be great if u can look on it , thanks!

[diegosouzapw]

Correct, production-reproduced bug fix — GET /api/quota/pools/[id]/usage now multiplies each plan dimension limit by accountCount. However, the PR targets the dead release/v3.8.49 and is BLOCKED. Please retarget to main and resolve the merge conflict — then it's good to merge.

[dpozimski]

Retargeted to main and resolved the conflict. The branch was originally cut from the release lineage, so rather than rebase 13 commits I rebuilt it from main and cherry-picked the fix commit, which applied cleanly. The conflict was all release-branch history, not the change itself. Re-verified against main: enforce.ts there still applies the same accountCount multiply, the 4 quota test files pass (23/23), and eslint is clean on both changed files. Should be good to merge now.