A counter reset can invent a traffic spike
Reproduce a 15-to-115 rate error with promtool. Trace raw-counter recording rules, hidden resets and missing-sample limits.
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Explore SaaS engineering through runnable examples and decision worksheets. Browse by topic or search all articles.
Presigned downloads: decide where revocation happens
Compare retained links, brokers and gateways in a runnable model. Define request admission and active-transfer limits.
Feature flag caches: keep tenant decisions separate
Compare four cache identities across 512 inputs. Reproduce tenant, role and snapshot collisions, then test the limit of revision-aware keys.
Soft delete and name reuse: make restore conflicts explicit
Run nine SQLite checks for tenant-scoped names, renamed restoration and unchanged IDs. Turn delete, recreate and restore into an acceptance brief.
JSON IDs: preserve identity across a JavaScript client
Eight IDs reveal four altered numeric round trips in Node. Strings and Python integers preserve all eight; test Map collisions and a strict decimal contract.
Outbound webhooks: pin the checked destination
Run 16 offline URL cases and a DNS rebinding counterexample. Inspect the connection plan, redirect boundary and tests the real worker still needs.
OIDC account linking: keep identity separate from email
Six lookups and eight link decisions separate issuer-subject identity from email, explicit account ownership and workspace connection policy.
Worker shutdown: stop taking jobs before draining
Four shutdown policies finish different sets of work. Run a two-slot queue simulation and separate admission, in-flight completion and cleanup.
Invoice rounding: preserve the total and the line identity
Compare independent rounding with a deterministic allocation. Run 3,750 exact-arithmetic cases and preserve line amounts through reversals.
LLM timeouts: keep uncertain usage reserved
Releasing an unresolved LLM request admits 120 credits under a 100-credit cap in this model. Compare retained reservations and duplicate settlement.
OAuth refresh token races: trace the lost response
A local model separates duplicate exchanges, stale writes and a lost response. Inspect six traces before retrying a rotating refresh token.
SaaS resource quotas: protect the last slot
Run eight SQLite cases: stale checks admit six projects under a cap of five. Inspect atomic reservation, retry receipts, rollback and duplicate release.