Built fast, never sized.
$725,391 a year
measured.

Tidepost’s engineers put thirteen changes in place across three accounts, estimated at $228,238 a year, 10.8% of the bill: notebooks that stop themselves when idle, developer instances that sleep outside working hours, gateway endpoints for S3 and DynamoDB, INFO instead of DEBUG in production, custom metrics without the per-post dimension, gp2 volumes moved to gp3, old exports and CI artifacts expired, and Transcribe run only on videos with speech. The first change went in on Tuesday, April 21.

Every change was approved by its owner at the readout, made by a Tidepost engineer through a pull request and the pipeline, and reviewed by Vantalect, which holds a read-only role and writes nothing to production. Each has a written way back, except three that remove something that does not come back, and the report names them. Nothing showed on an invoice yet: the Cost and Usage Report needs seven full days after a change before it can be read.

Eleven changes went in, worth $400,334 a year, 19.0% of the bill and the heaviest week by value, which brought the total in place to 24 changes and $628,572 at estimate, 29.8% of the bill. The sizing changes made hardware smaller or fewer: an embedding endpoint that had been using one GPU of four moved to a smaller instance, the largest single saving in the engagement; the production nodes consolidated under Karpenter; the transcoders and the API tier scaled on demand, the API tier on Graviton; the cache nodes, the read replicas, and the Kinesis stream came down to what they use. The demand changes made the work smaller: a lighter rendition ladder on cellular, shipped with an app release, and a moderation route that sends the second, more expensive video path only the newer accounts’ videos and the reported ones.

The commitment came last on purpose. A one-year Compute Savings Plan at $7.27 an hour was sized on the always-on floor of $14.26 an hour of On-Demand usage that every change on the roadmap leaves, so the deferred changes cannot leave it underused. Gwen Tallis approved it in writing before it was bought on Thursday, April 30, in the payer account with sharing on. A change to the same moderation path, sampling frames half as often, was declined by its owner at the readout, and it is in the calls below with her reason.

Seven changes worth $152,131 a year went in, 7.2% of the bill, bringing the total in place to 31 changes and $780,703 at estimate, 37.0% of the bill. The week was about data that gets old: telemetry converted to Parquet at ingest and the queries moved onto it, old renditions moved to Glacier Instant Retrieval, application logs kept for less time once counsel’s copy of the oldest months was safe, and the snapshot chains an old cron job left behind deleted, with AWS Backup the only schedule from here. Wednesday, May 6 was the last day a change could go in and still have seven full days on the Cost and Usage Report before week six read it.

Five guardrails were built in the week, beside two the engagement inherited from earlier ones, so seven in all, each with one owner who will be asked if it fails. Four prevent the waste at creation and three detect it soon after, and the report says what each one cannot see. Gwen Tallis declined the SageMaker Savings Plan on Tuesday, May 5 because she wants the Inferentia2 move first. The terms count a change approved at the readout and declined later at its estimate, so it is in the gate math at that estimate, and it is on the page below as a call.

Every change was measured the same way on Tidepost’s own Cost and Usage Report: the public On-Demand cost of the changed resources over the seven days before the change against the seven days after it, the day of the change in neither, annualized, so a Savings Plan is never counted inside another change. 31 changes measured $725,391 a year, 34.4% of the bill and 92.9% of their $780,703 estimate, and every miss is published at its measured value. Ten matched their estimates exactly. The largest miss was the rendition ladder, at 53.6% of its estimate: only 52% of viewers had the new app in the window.

The handover gave every remaining change an owner and a date, set the first monthly cost review for Tuesday, June 9, and listed the guardrails. The second invoice, $14,875, was issued with the measurement report, so Tidepost paid $29,750 in total. Tidepost then saved its own Well-Architected milestone with no High-Risk Issues left, which this page shows and never counts.