All lessons
Series::flat(TypeId::Bool, ...) returns an empty Series Staledataframe28 Sep 2026StringViewSet owns its strings, so views into a temporary one dangledataframe28 Sep 2026A large clap derive command tree overflows the 2 MiB stack of test threads in debug buildsrust28 Sep 2026A range-for over a member of a temporary reads freed memorycpp28 Sep 2026A raw string literal ends at the first )", even inside a quoted patterncpp28 Sep 2026After libgit2 rewrites the index, git status can miss a same-second, same-size editgit28 Sep 2026After rgit stage --hunk, check the index before committinggit28 Sep 2026Build a ground-truth set for PDF extraction from arXiv LaTeX sourcestesting28 Sep 2026Build PCRE2 as a static 8-bit library with JIT through CPMcmake28 Sep 2026candle-core 0.10 and later always pull in tokenizers and the Oniguruma C librarycandle28 Sep 2026Clang calls this unused in a generic lambda that calls a member without this->cpp28 Sep 2026granite-docling-258M runs at about 1 token per second through transformers on Apple Siliconpython28 Sep 2026How git's octopus merge works, for a tool that must match itgit28 Sep 2026libgit2 applies a hunk at its new-side start line, so a hand-built one-hunk patch needs that line on the + sidegit28 Sep 2026libgit2 ignores GIT_CONFIG_GLOBAL and still reads ~/.gitconfig and ~/.config/git/configgit28 Sep 2026libgit2's cleanup_state also deletes BISECT_LOG, which breaks a bisect in progressgit28 Sep 2026pdftotext -bbox-layout splits small caps, section numbers and captions in ways a parser must undopdf28 Sep 2026Pruning must key a literal the way the index stored the valueindex28 Sep 2026rait finds PDF tables with Table Transformer in Rust, and word positions fill the cellspdf28 Sep 2026rait prefers pure-Rust crates and allows C only where no good Rust option existsrust28 Sep 2026rait's held-out PDF evaluation set: 12 arXiv papers and the scores to beattesting28 Sep 2026rgit stage --hunk reports success for a hunk it did not stagestaging28 Sep 2026Run many coding agents on one Rust repository without overloading the machineagents28 Sep 2026Stale gcov data makes tests crash at exit after a rebuildtesting28 Sep 2026Table Transformer structure recognition misreads small tables that are scaled up to 800 pxpdf28 Sep 2026transformers 5 refuses the Table Transformer v1.1 config because dilation is nullpython28 Sep 2026Twin-repo git comparisons flake unless every commit has a fixed date and asserts match whole tokenstesting28 Sep 2026zsh does not split an unquoted variable into words, unlike bashshell28 Sep 2026?? followed by ', (, ) and others in a C++ string is a trigraphcpp27 Sep 2026[[maybe_unused]] on one structured binding name is a C++26 extensioncpp27 Sep 2026doxygen docs/Doxyfile from the repo root writes a stray doxygen/ folderdocs27 Sep 2026PyObject_IsTrue(v) > 0 ? true : fallback turns False into the defaultpython27 Sep 2026A byte pre-filter on JSON lines must not assume how the writer spelled the JSONjson27 Sep 2026A consumer that stops reading a bounded channel on error leaves its producers blocked forevercpp27 Sep 2026A false [ ... ] && cmd as the last command of a shell case branch makes the script exit 1shell27 Sep 2026A new query leaf form must be handled in every place that reads query leavesquery27 Sep 2026A test that shells out to a real CLI with side effects can change the user's real configtesting27 Sep 2026A/B timings on a busy shared machine both hide and fake regressionstesting27 Sep 2026Agents do not reliably load a skill, so must-follow rules need always-on context or toolsagents27 Sep 2026Agents reach rkb through tools: a Claude Code plugin with an MCP server, and a pi/omp extensionintegration27 Sep 2026Aggregation tier state that spans builds and processesindex27 Sep 2026An index build after a tier-served query fails with "Cannot upgrade RocksDB instance"index27 Sep 2026An unquoted null in a YAML list is a null, not the string "null"yaml27 Sep 2026candle compiles Metal kernels on the first GPU run of each binarycandle27 Sep 2026Check a hand-written parser's grammar with a Lark LALR(1) copy and one shared sample fileparsing27 Sep 2026Claude Code plugins from a local marketplace: layout, updates, tool names and permissionsclaude-code27 Sep 2026Code that assumes the dftracer schema breaks other record schemas silentlyviews27 Sep 2026corfu's auto popup also opens in the minibuffer, including evil's : lineemacs27 Sep 2026CTest tests that run a build in the build tree must share RESOURCE_LOCK build_treetesting27 Sep 2026Delete exactly one key through a range-delete-only interfacerocksdb27 Sep 2026duql replaces dictionaries, resolved columns and the metadata phase with queriesquery27 Sep 2026eglot freezes Emacs when a language server asks to watch files outside any version-control rootemacs27 Sep 2026eglot inlay hints make cursor movement laggy in large files while the server is busyemacs27 Sep 2026Emacs on macOS can only make the whole GUI frame see-through, not just its backgroundemacs27 Sep 2026evil-collection binds SPC in many modes, which hides a global SPC leaderemacs27 Sep 2026For design questions, research and discuss first; new dependencies are fine when they win on performanceworkflow27 Sep 2026How today's filter language treats missing fields, null, types and patternsquery27 Sep 2026Laya asks whether the lesson is about the same problem, not whether it helpsrerank27 Sep 2026libdeflate cannot recover a cut gzip member, so decode the last member with zlib streaminggzip27 Sep 2026Many small parallel Accelerate sgemm calls are slower than one large callmacos27 Sep 2026Never search the whole disk from the root folderagents27 Sep 2026On macOS the first GUI frame of an Emacs daemon turns the menu bar back on in terminal framesemacs27 Sep 2026pi and omp extension events for compaction, shutdown and commandspi27 Sep 2026Pruning evidence is sound only for the records it was built fromindex27 Sep 2026Recall adds only a clear top lesson: relevance 0.85 and 0.10 above the nextrerank27 Sep 2026Record the old parser's output over every in-repo query before replacing the parsertesting27 Sep 2026rkb captures sessions on signals and distills only when asked, with no model of its owndistill27 Sep 2026rkb prints human text by default, and agents pass --toonoutput27 Sep 2026Run the Python suite and the docs build without installing anythingtesting27 Sep 2026The aggregation tier holds no file id, so one file's rows cannot be replacedindex27 Sep 2026The query cache lives beside the index in .dftindex-cache, not inside .dftindexindex27 Sep 2026The Rust MCP crates all depend on Tokiorust27 Sep 2026Time two builds with one scratch program, using the build's own compile and link linestesting27 Sep 2026Typed record decode got 35% slower until per-leaf work left the hot loopviews27 Sep 2026Which (void) casts may stay in dftracer-utilscode-style27 Sep 2026Which View reads return dftracer metadata recordsviews27 Sep 2026With rebase.updateRefs on, a backup branch made before a rebase does not keep the old historygit27 Sep 2026