Jilai Cheng

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Scholarly paper search APIs — 2026-08-20
Twenty-one scholarly search APIs were probed with live requests. Every endpoint and field shape below is the response that came back, not what the documentation
Nix fixed-output fetches through the HTTP proxy — 2026-08-17
A flake's nix flake check failed downloading two fixed-output sources: musl.libc.org and a repo.or.cz snapshot. The download failed twice: first with a TLS conn
nix flake check does not run your test apps — 2026-08-17
A workspace's test suites were wired as apps.${system}.test flakes and the gate was nix flake check. Every check was green. Running nix run .#test across the sa
buildDotnetModule: JSON lockfile and the silent AOT skip — 2026-08-16
nixpkgs buildDotnetModule parses nugetDeps by filename suffix: a .nix path is callPackage'd as Nix code, anything else is lib.importJSON (add-nuget-deps/default
dotnet: no cargo-style toolchain self-satisfaction — 2026-08-16
Go's GOTOOLCHAIN=auto downloads the go.mod-declared toolchain on demand (go.dev/doc/toolchain). dotnet's global.json pins the SDK version but only selects among
LoongArch linker relaxation: the pcaddi fold — 2026-08-16
R_LARCH_RELAX is relocation 100 in the LoongArch ELF ABI: Instruction can be relaxed, paired with a normal relocation at the same address. The assembler emits i
Nix store epoch mtimes defeat mtime-based change detection — 2026-08-16
NixOS deploys a config file with environment.etc as a symlink chain into the Nix store. A switch replaces the target with a new store path whose name embeds the
TCO: the self-tail-call jmp must precede the param spills — 2026-08-16
Tail-call optimization in a compiler that spills parameters to stack slots: the self-tail-call jmp target must be BEFORE the parameter re-spill block. The body
VLC 3.0.23 ignores --http-user-agent — 2026-08-16
VLC 3.0.23 sends a hardcoded User-Agent on every HTTP request. --http-user-agent on the command line and http-user-agent= in vlcrc are both ignored. A GET to a
YouTube timedtext 429 escalates with retries — 2026-08-16
yt-dlp fetches subtitles from youtube.com/api/timedtext. A 429 on that endpoint returns Google's "your computer or network may be sending automated queries" HTM
A 403 that was a version field, not a block — 2026-08-15
Uploads returned HTTP 403 (出错啦 / 服务器正在休息) from every client and every egress: the campus IP, the lab IP, even a WARP tunnel. It looked like a network block. It
Blank pages: the shell, not the script — 2026-08-15
A classic script inside <head> executes while the parser is still in the head. document.body is null at that moment; the first document.body.appendChild throws.
bun --compile binaries in Nix: patch only the interpreter — 2026-08-15
bun build --compile packs the JS runtime and the bundle into one ELF. EYG (Eat Your Greens), a statically typed functional scripting language by Peter Saxton, s
DeepSeek Harness on NixOS: the bash tool that assumed /bin/bash — 2026-08-15
DeepSeek Harness (dsh) has two model-facing bash tools with different executors. The standard agent preset mounts dsh-tool-bash: each call is a fresh subprocess
EYG: a typed functional language for makers — 2026-08-15
EYG (Eat Your Greens) is a statically typed functional scripting language by Peter Saxton (CrowdHailer, Gleam contributor). It is implemented in Gleam, Apache-2
Generations that lie: boot regressions hide under long uptime — 2026-08-15
A one-line change to a boot-time provisioning script broke wifi for 44 generations before anyone noticed. The machine never rebooted. The running system is not
kotlin-toolchain: Gradle distribution mirror and the 2.3.10 power-assert runtime gap — 2026-08-15
A Gradle Tooling API client downloads the Gradle distribution itself when the connector specifies none. GradleConnector.newConnector().forProjectDirectory(...)
Mill 1.1 build files: what changed — 2026-08-15
Mill 1.1 build files compile with Scala 3: the mill jars are _3 artifacts, type errors print union types (Seq[mill.PathRef | os.Path]), and macro errors read Ta
Self-contained Clojure builds with Mill — 2026-08-15
Mill declares its JVM in a .mill-jvm-version file (name:version, e.g. zulu:26), a //| mill-jvm-version build header, or the declarative jvmVersion: key, and pro
qutebrowser IPC: JSON, not plain text — 2026-08-15
The IPC socket speaks JSON, not plain text. One message is one JSON object: args (each element one command string, colon included), target_arg, version, protoco
Transcripts bridge what titles can't — 2026-08-15
Scoring candidates by TF-IDF cosine against a corpus of talk titles separated junk from tech, but not desired from boring: a "how to switch to Linux" tutorial s
ty, the Astral type checker: strict mode without --strict — 2026-08-15
ty 0.0.67 has no --strict flag; ty check --strict fails with unexpected argument. Strictness is configured per rule in [tool.ty.rules] with severities ignore, w
The stub that broke bilibili transcoding — 2026-08-15
yt-dlp -f "bv*+ba/b" silently fell back to the combined muxed format (18) for one video. Through the proxy egress that format arrived as a 1.5 MB header-only st
DeepSeek Harness: Everything is a Plugin — 2026-08-14
DeepSeek Harness (dsh) is DeepSeek-AI's open-source agent harness. License: MIT. Version 0.1.0-rc.6, developer preview; the README warns of compatibility-breaki
Rebuilding git history from per-file change chains — 2026-08-14
A linear history can be rebuilt commit by commit with git commit-tree. The final tree stays byte-identical: every file's last version is the original last versi
The publication date is a declaration — 2026-08-13
File mtime measures disk writes, not publication. A fresh clone stamps every file with the clone time, so a post from a year ago shows today's mtime. Ordering b
Identifying pi sessions behind the opaque pi process; the subagent O(n^2) hot path — 2026-07-17
The pi wrapper runs exec -a: every pi process shows cmdline pi (argv: model, session, prompt) is invisible to ps/pgrep. Running several sessions means several i
pi 0.84.0: sendUserMessage never dispatches extension commands — 2026-07-16
docs/extensions.md and the shipped example examples/extensions/reload-runtime.ts document a tool-to-command handoff for reload: the tool calls pi.sendUserMessag
pi as a programmable agent: RPC mode and declarative subagents — 2026-07-13
pi is a coding agent that runs headless over a JSON protocol, and it ships no subagents or plan mode: "you can ask pi to build what you want or install a third
Hyprland 0.56: Lua config, dispatch, and screenshots — 2026-07-05
Hyprland 0.56 configures itself from Lua: the shipped share/hypr/hyprland.lua plus the config deployed with the compositor. hyprctl dispatch wraps its argument
Codeberg edge drops repeat connections; pacing and the API are stable — 2026-07-02
The first request to codeberg.org succeeds. Repeats within about 40 seconds time out after the TLS handshake with 0 bytes received.
YouTrack: the REST API takes the SPA's own token — 2026-06-18
JetBrains' kotlin-toolchain routes GitHub issues to YouTrack. Its only issue template is a form whose required checkbox reads "I have read the message and will
Bilibili video uploads accept a browser session — 2026-06-01
bilibili has two login classes. Web login issues SESSDATA, a cookie. App login issues access_key, a token. The video-submit endpoint x/vu/client/add rejects coo
A resolver that withholds video sites at night — 2026-05-28
A campus DNS server answered NXDOMAIN for the seven big video sites at night and resolved them again by morning. Control domains always resolved, and direct TCP
Session cookies carry their own expiry — 2026-05-10
A bilibili login cookie encodes its own deadline. yt-dlp rewrites the cookie file you hand it. The two facts together shape how long a media playback setup stay
Debugging traps that recur — 2026-03-27
Every one of these started as "my change did nothing" and ended as a two-line explanation. None is exotic; all of them recur. The theme: verify against the runn
Rotating credentials in a systemd credential store — 2026-03-19
Static secrets need provisioning once. Tokens that expire or get revoked need a refresh loop: a timer re-exports the current bytes from each live source, diffs
systemd already does what you were about to write — 2026-03-16
Four mechanisms turned out to be systemd builtins: a secret path list, a backlight-restore loop, a wait-online "disable", and a udev RUN+= shell. The rule: ask
Declarative configuration and secrets pipelines — 2026-03-12
The repo IS the system: services, configs, secrets, even the AI model the coding agent uses are declared, committed, rebuilt. User-state files under the home di
Title embeddings, not whole content, for topic-level duplicates — 2026-03-05
A blog gate: a new topic that duplicates an existing post's topic must be blocked, and the author updates the existing post instead of creating a new one. The c
Verifying what you write about software — 2026-02-28
Before writing about a claim, check it against the source. Memory and "everybody knows" are wrong often enough to make this the default workflow. Each claim bel
Keeping a language model out of your prose — 2026-02-23
A model composing prose adds words that carry no fact: invented reasons, intensifiers, metaphors. Two checks remove them. The first is a deletion test; the seco
Python set iteration order is seed-dependent — 2026-02-19
Set iteration order derives from element hashes. String hashing is salted per process by PYTHONHASHSEED, so the same set iterates in a different order in every
Nix strings inside strings — 2026-02-15
A systemd unit needed to run a bash loop. The natural first attempt put the whole one-liner in a double-quoted Nix string and blew up the parse; the fix is Nix'
Exact config key names and silent ignores — 2026-02-04
Goal: turn off LLMNR and mDNS advertising on a campus network. One line worked, the other vanished, with no error anywhere. Key names are exact in case and spel
ssh resolves ~ from the passwd database, not $HOME — 2026-01-30
A root systemd unit running an ssh reverse tunnel failed in a restart loop with Host key verification failed (exit 255). The unit set environment.HOME=/home/<us
How to submit a change to Guix (2026) — 2026-01-24
Since 2026-01-01 Guix accepts pull requests on codeberg.org/guix/guix; the email route (guix-patches@gnu.org) is retired. The GitHub mirror is read-only; GitHub
kmscon as the console — 2026-01-10
The kernel console could not render bright backgrounds distinctly on the laptop panel. kmscon, a KMS/DRM terminal emulator, replaced it: 256 colors, pango fonts
HDA codec debugging from userspace — 2025-12-19
A laptop speaker kept playing together with the headphones, and the mixer controls did nothing. Fixing it meant reading the HD-audio codec and driving it with H
Mic hum: diagnose with a 10-second recording — 2025-12-05
A microphone picks up mains hum. The right fix depends on what the noise is: tonal hum at 50 Hz (China mains) with odd harmonics wants an EQ cut; broadband hiss
Faster substitutes and package management from China — 2025-11-16
Guix queries substitute servers in order and falls back. Put the fast ones first, keep the official ones as fallback, and prefer API clients over git for repo w
Guix firmware: why a machine can silently lose its sound card — 2025-11-14
A laptop rebooted into a working system with no sound at all: /proc/asound/cards empty, dmesg showing sof_probe_work failed err: -2 for the Intel audio DSP. The
guix system reconfigure: what it does and does not do — 2025-09-29
guix system reconfigure is transactional but not a restart: it stages the new system and starts what is missing. The manual says what it does not do, plainly, a
SSH, keys, and hostnames across machines — 2025-09-09
Three systems on two laptops, one jump host, and a network that renames your computers. All of it declared, none of it hand-edited.
What happens when a laptop joins a campus/enterprise Wi-Fi — 2025-08-25
A failure that looks like "wifi is broken" lives in one layer of a four-layer stack: the driver owns the radio, wpa_supplicant scans and runs EAP, systemd-netwo
Shipping your Emacs config as part of the OS — 2025-07-30
An Emacs config that lives in the system repo, pinned per generation, edited like any other system file, with no ~/.emacs.d to maintain.
Emacs face colors on terminals — 2025-07-22
Goal: one theme that works on the kernel console, on kmscon, and in a GUI. The terminal advertises its colors in three different ways; Emacs builds a different
The escape key: five layers — 2025-05-09
Goal: make Escape cancel like C-g, make the Windows key Meta, and leave Alt dead. Each attempt failed for a different reason, and each reason is a documented la
NixOS debugging essentials — 2025-04-28
The flake layout, what switch does, and how the machine gets its name. All of it is declared, none of it is remembered.
Building this page with DOM, CSSOM, and Houdini — 2024-11-22
Every page has a generated static shell: title, description, canonical, JSON-LD, and two body script tags. common.js builds the DOM and the stylesheet; a per-pa