Portfolio and notes
I build web products and AI systems, document engineering decisions, and keep a public trail of projects, technical notes, and experiments.
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A reader said "every post has a fair few typos", but that month no node in the pipeline had failed once. Six defects, none of them a failure: every one was a component doing exactly what it was told, returning 200, then going wrong in the inch it was never told about. Plus the question I now keep on my review list: is this success signal load-bearing?
Researcher degrees of freedom are the real adversary in quantitative research. From predeclaration, orthogonality prescreens, and Gate A to the neutralization ladder and a forward shadow book: a control process I have run for over a year and violated a few times myself. It does not guarantee profit; it guarantees I can tell when a result is fake.
Large immutable files and small highly sensitive config are the two poles a database migration never covers: an in-place storage-layer swap, a three-tier secret resolution order, half-finished-work archaeology, and the discipline of export, off-site backup, reconcile, only then delete.
How to cut a migration that touches every read and write path into six independently shippable, independently reversible phases: same-interface swaps, the dual-write safety net, write-stop as the only irreversible point, and the fourteen production bombs adversarial review caught.
The bill went from a few hundred NTD to over forty thousand, and nobody broke in — every cent was spent by my own code. A five-layer drill-down from invoice total to function name, and why payload x distance costs more than read count.
Resident Personal Assistant Series: Parsing encrypted PDF statements, integrating multi-broker APIs, handling T+2 settlement lags, and building automated research report crawlers.
Building a resident assistant on Hermes Agent: six traits that stop it being a chatbot, what is genuinely clever about the Hermes agent mechanism, and the day it became trustworthy.
Full-Stack Architecture Series: Not all APIs deserve the same TTL. How to combine Edge CDNs, Redis in-memory caching, and Cache-Aside patterns to prevent Cache Stampedes.
Environment layering is not enterprise ceremony, but a risk-reduction pattern: how to boost release reliability using branch-to-environment mapping, preview deploys, secrets isolation, and production guardrails.
Production lessons: Step-by-step checkpoints and rerun_from recovery, preventing reasoning model token truncation, pre-persistence gates, and concurrency budgets.
How an unstructured financial podcast data pipeline evolved from a single prompt into a decoupled multi-agent topology using LangGraph.