Category Engineering

Hands-on engineering notes: deployment, evaluation and operations, with reproducible steps.

Text-free abstract artwork on a pale violet background: four identical outlined circles with filled centres in a row, joined by a straight line; a small cluster of four linked circles at the top left; and a large pale disc in the top-right and bottom-left corners.

Engineering

Keeping members-only content out of AI answers and read-aloud audio: how AI Chat for Amazon Bedrock gets “the text a guest sees”

Pinned source and synthetic tests: AI Chat for Amazon Bedrock renders posts signed out, drops blocks with visibility rules and skips noindex pages.

October 7, 2026

Conceptual illustration: a magnifying glass at top left; across the middle, three pale circles side by side, each holding an outlined diamond above a short horizontal line and separated by thin vertical lines; two large pale circles in the background at top right and bottom left; no text, numbers or charts.

Engineering

Why a cheaper bracket was still rejected: checking 3-axis milling setups, holes, screw clearance and unit-cost estimates on the B-Rep

pai-design-workbench 3-axis DFM: a compact bracket estimated at 14.69 EUR meets a 16 EUR target, yet ribs block two M5 holes and it fails hole-edge distance.

October 6, 2026

Conceptual illustration: an abstract geometric composition of parallel circles and lines evoking a comparison of estimate and measurement, with no text, numbers or charts.

Engineering

Checking an agent’s physics estimate against held-out solver results: the evaluation passed, but the height trend was backwards

The model returns only three bounded exponents; a template builds the estimator. One run: median 0.114, worst 0.321, Spearman 0.95, passed, height sign wrong.

October 5, 2026

Conceptual illustration: in the top-left corner, a central circle joined by three lines to three small circles; across the middle, three identical circles side by side, each containing a diamond outline with a short horizontal line beneath it, separated by thin vertical lines; two large pale circles in the background; no text.

Engineering

Reviewing a skill means more than SKILL.md: checking scripts and references with dsh-skills-anywhere’s directory manifest

SKILL.md unchanged, scripts changed? dsh-skills-anywhere 0.9 hashes every file: compare exits 0, 1, 2; MCP loads reject changes; what a match cannot prove.

October 3, 2026

Text-free conceptual illustration: a left-to-right timeline composition showing a chat request passing several checks before it reaches order data.

Engineering

“Package”, “returns” or “shipped” alone is not enough: how a WooCommerce chat assistant decides a message is about an order

AI Chat for Amazon Bedrock sends a customer’s orders to the model only if the question points at an order: 11 patterns, ownership checks, fields, blind spots.

October 2, 2026

Factory Twin scene rendering from Robot Reel documentation, not paired-trial footage or a real-world photograph.

Engineering

Reviewing a factory digital twin’s decisions: paired runs, losing seeds included

Factory Twin Lab pairs closed-loop and shadow runs on identical disturbances: 0 vs 11 spindle failures over 12 pairs, yet output rose in 10 and fell in 2.

October 1, 2026

The raw trace on the left and the answer’s factual claims on the right flank a neutral inspection lens; a separate lower panel labels the model explanation not_assessed, outside automatic factual checking.

Engineering

Checking a model’s explanation against the original robot recording: what Robot Reel’s review-claims can establish

Match a raw answer to a SmolVLA trace. Explanation: not_assessed; unassessed facts give exit 1. Keep format failures unchanged.

October 1, 2026

Baseline complete-plan matches are 15/24 and the candidate has 19/24; a blocked gate indicates that case-level checks still reject the upgrade.

Engineering

Reviewing a model upgrade: complete-plan matches rose from 15/24 to 19/24, so why does the EvalArc gate still reject it?

Recompute a model-upgrade verdict from pinned, verified records: the total rose, yet 10 blocking checks trace to format or schema failures in two cases.

October 1, 2026

Version consistency, release inspection and SVN appear on the left; a separate right-hand note links same-version re-upload to stale CloudFront CSS, not to SVN.

Engineering

Lessons from releasing a WordPress plugin: version numbers, the release gate, SVN and CloudFront caching

Releasing AI Chat for Amazon Bedrock: 3-way version check, a gate that reports skip, SVN, and CloudFront's stale CSS by ?ver= after a same-version re-upload.

September 28, 2026

Three layers show CloudFront/ALB routing, the WordPress application, and persistent EFS/Aurora state.

Engineering

Hosting WordPress on AWS with CDK: trade-offs of a shared ALB, CloudFront, EFS and Aurora

This site's WordPress on AWS: Fargate, the site on EFS, Aurora Serverless v2 pausing to 0 ACU, a shared ALB gated by a CloudFront secret header. Choices, costs.

September 28, 2026

A flat viewer–CloudFront–ALB–Apache–PHP chain contrasts viewer-influenced X-Forwarded-For with the viewer-address header generated by CloudFront.

Engineering

Getting the visitor IP behind CloudFront + ALB: why you should not parse X-Forwarded-For in PHP

The WordPress image's mod_remoteip already rewrites X-Forwarded-For, so parsing it in PHP yields forged IPs. Use CloudFront-Viewer-Address, given 2 conditions.

September 28, 2026

A browser requests the alias domain directly through ALB with an example path and query, receives 301 and Location, then follows the canonical host with the same path/query. Globe icons mean domain names, not CloudFront hops.

Engineering

Redirecting extra domains to the main domain with a 301 from an ALB listener rule

One extra SNI certificate and a host-header rule on the HTTPS listener 301 alias domains to the canonical one, keeping path and query. With DNS and curl checks.

September 28, 2026