I build tools for the boring failure modes — the ones where nothing crashes, nothing alerts, and the data has been quietly wrong for three weeks.

A scraper that returns 0 results because it parsed a block page as data. A bot that died on one API timeout at 3am. A monitor that alerts on the timestamp instead of the price. Every repo below exists because of one of those.

Everything here runs. Most have a one-command demo that needs no key, no signup, and no network.

Pull requests into projects I don't maintain. Same rule in each: a test that reproduces the defect before the fix, so the suite proves the fix does something. Every one below fails against the unpatched code.

cachix/secretspec #358 — a JSON null in a secret reference became the four-character password null, satisfying a required secret. The maintainer asked for the three copies of that rendering to be shared; doing so surfaced the same defect in a third call site, and the existing suite then caught me flattening a difference between them that was deliberate and tested. Merged 119 minutes after opening.

cachix/secretspec #352 — close() deletes the temp files holding as_path secrets. Python and Ruby stopped at the first file the OS refused, stranding every later secret on disk. Go and .NET already recorded the error and cleaned up the rest — the project's own contract, unimplemented in two of six SDKs.

bsorescu/herdr-mobile #1 and #2 — a redraw skipped when it would be identical, and the polling SSH calls moved off the event loop. Both came back with changes requested, and the review was the useful part: the maintainer showed that two of my tests passed with and without their fix, which is the one thing a regression test must never do. Fixed, plus a third bug the re-check turned up — the skip path never re-pinned the log, so the last rows sat under the remote bar indefinitely.

c-rack/cbor-java #265 — the canonical map-key comparator compared key bytes with Java's signed byte, so a byte 0xff sorted before 0x01 — the reverse of the byte order its own Javadoc specifies. Every canonical map with a high byte in a key came out non-canonical. Merged same day.

c-rack/cbor-java #266 — the decoder read a declared array/map/string length and preallocated a collection of that size before reading a single byte of payload. Five bytes — 9A 7F FF FF FF, an array claiming 2,147,483,647 elements — were enough to OutOfMemoryError the process. A parser is exactly where untrusted input arrives, so the length has to be treated as a claim, not a promise; preallocation is now bounded by what the stream can actually supply. Merged.

networknt/json-schema-validator #1273 — uniqueItems compared items through Jackson node equality, which is type-sensitive, so [1, 1.0] validated. The official conformance suite covers the rule with [1.0, 1.0, 1], which passes either way, so 8,479 green tests and the rule still broken. Merged.

json-c/json-c #957 — strict mode rejected a leading zero but checked nothing else about a number's shape, so 2.e3 and 1. parsed clean. And because json-c writes the token back out verbatim, it then emitted JSON that stricter parsers reject — a library quietly manufacturing invalid documents. The fix enforces the whole RFC 8259 number grammar. Merged.

The ones worth reading:

pulp-platform/axi_stream #9 — a 64→8 AXI-Stream downsizer's fast path consumed a beat carrying TLAST but never padded, so a frame one beat past a word boundary was silently truncated and its remainder left merged into the next frame. Only lengths ≡1 (mod 8) reach it, and only with TVALID held high — a sweep of every length found it, a single test case would not.

hashicorp/go-retryablehttp #297 — Retry-After seconds are converted with time.Second * time.Duration(sleep). A Duration counts nanoseconds, so any value past ~292 years wraps negative, and time.NewTimer fires immediately on a negative duration. A server asking to be left alone was answered with a burst of retries. The guard for a negative value in the header already existed; a positive one that becomes negative did not.

cachix/secretspec #352 — close() deletes the temp files holding as_path secrets. Python and Ruby stopped at the first file the OS refused, stranding every later secret on disk. Go and .NET already recorded the error and cleaned up the rest — the project's own contract, unimplemented in two of six SDKs.

tenstorrent/tt-npe #131 — an empty golden-cycle map left a {Cycle::max(), 0} sentinel that underflowed to 1 on subtraction. Worse than a zero: 1 passes the > 0 guard written to suppress exactly that case, so a 100-cycle estimate was reported as 9900% error.

keephq/keep #6698 — a CEL filter was translated to JavaScript with replace(/contains/g, "includes"), rewriting the inside of quoted search strings. description.contains("contains") searched for "includes", and a field named contains_pii became one that doesn't exist.

phpseclib/phpseclib #2165 — divide() returns the "common residue", the first positive modulo, so only a negative remainder has the divisor added. When the division is exact the remainder is already zero, and the pure-PHP engines added the divisor anyway: -256 / 256 came back with a remainder of 256, a residue equal to its own modulus. GMP and BCMath return 0, so the answer depended on which extension happened to be installed — and the PHP engines are the fallback when neither is, in a cryptography library. Found by running 1278 operations through all three engines and diffing; 32 disagreed, and the documented rule sided with BCMath in all 32. Their testDivide only ever divides a positive number exactly.

mholt/PapaParse #1142 — the UTF-8 BOM was stripped for string input only. A File, a download or a Node stream went straight to the chunk parser, so the mark stayed inside the first field of the first row, where nothing renders it and row[0] === 'name' is simply false. header: true hid it, because the header is stripped separately. Both existing BOM tests pass a string, and the repo's own utf-8-bom-sample.csv is only ever read into a string — the streaming path had no BOM coverage at all.

webauthn4j/webauthn4j #1495 — the CTAP2 canonical CBOR serializer listed an RSA COSE key's fields negatives-first and descending, so a public key {1:kty, 3:alg, -1:n, -2:e} serialized with its keys ordered -2, -1, 1, 3 instead of the canonical 1, 3, -1, -2. Canonical CBOR orders map keys by their encoded bytes — positive labels before negative — and the sibling EC2 and EdDSA serializers already do, which is what proves the RSA list is a mistake and not a convention. The output isn't canonical, so anything that re-encodes or thumbprints the key diverges — in a WebAuthn/FIDO library. Built the 585★ project and asserted the serialized map starts with kty; it started with a negative label. Merged.

dryruby/json-canonicalization #7 — numbers were formatted with "%.15E", which yields 16 significant digits, but an IEEE-754 double needs 17 to round-trip. So 0.1 + 0.2 canonicalized to "0.3" — a string that parses back to a different double, in a scheme whose entire purpose is that two parties hash identical bytes. The maintainer had commented the failing cases out as "Outside Ruby Range"; they weren't — 5e-324 and Float::MAX are perfectly representable, they just needed the 17th digit. 9,152 of 20,000 random doubles came out wrong; the fix takes it to zero.

Also: semver4j #467 (compareTo threw NumberFormatException on a spec-valid numeric prerelease identifier past Long.MAX_VALUE), gronx #71 (0 0 31 * * returned overflow dates — a February 31st as March 4th — that its own matcher then rejects), luxon #1799 (fromISO accepted out-of-range UTC offsets like +00:60 and +24:00 and silently normalised them, while rejecting the same out-of-range clock fields), pathspec #130 and node-ignore #163 (both matched POSIX classes like [[:digit:]] against nothing, so Black / pre-commit / ESLint / Prettier disagreed with git on which files are ignored), linebreak #53 (missing Rule LB30's East Asian exception, so a line break before a wide bracket like 〈 or （ was wrongly forbidden), whatwg-url #46 (an opaque-path space before ? or # was not percent-encoded as the current URL Standard requires), didwebvh-py #41 (a DIF did:webvh implementation hashed DID-log entries through a non-RFC-8785 canonicalizer that turned integers ≥ 2^63 into JSON strings, so its SCIDs disagreed with any conformant verifier), nanorix-verify #1 (a Go JCS encoder stripped the + from positive exponents and kept the padded zero in negatives — 1e21→"1e21", 1e-7→"1e-07" — breaking its own documented byte-equivalence to Rust serde_jcs), jsoncanon #1 (same 16-digit float bug, in Python; their own test already expected the correct output, so the suite shipped red), keep #6687 (results returned twice), #6688 (json.loads("123") returns an int without raising, so only dict/list parses are accepted), tt-system-tools #28 (hugepage setup replaced the allocation instead of extending it), pulp-ethernet #6 (receive path never drove TKEEP, so a consumer read zero valid bytes in every frame), secretspec #358 (a JSON null became the four-character password null), sqlparse #876 (keyword_case recased the contents of a time zone literal, because the AT TIME ZONE 'Asia/Tokyo' rule matched the literal as part of the keyword; the existing test used 'UTC', which reads the same either way), CsvHelper #2387 (a UTF-8 BOM was stripped only on the first buffer fill, so a file whose BOM straddled the boundary kept it inside the first field — the tests for it passed with and without the fix, because xUnit's collection comparer does not surface a leading U+FEFF).

Config-driven scraping for sites that don't want to be scraped. Adding a site is a YAML file, not code. The core idea: a block page returns 200 OK, so every response is classified before extraction — WAF, captcha, rate-limit, empty shell — and a layout change fails loudly instead of silently writing blanks. Falls back to search-engine discovery when a site's own search is closed off.

python -m stealth_scrape --site olx --query "rtx 3090" --out results.csv

Real extraction output from live product pages, plus a write-up of four layout traps that produce a scraper which looks correct on your test page and returns nulls across a catalogue — including the price living in a visually-hidden node that Selenium's .text returns empty for.

Real-time dashboard: FastAPI, WebSocket streaming, live candlestick charts, dark/light themes. Instrument switching without reconnecting. Tabular figures so columns don't jitter twice a second — the detail you only notice after sitting in front of one for an hour.

pip install -r requirements.txt && uvicorn app.main:app

A bot built around what happens when the API doesn't answer. Transient and permanent failures are separate types — a 502 retries, a 401 never does. Backoff uses full jitter so retries don't land as one synchronised stampede. Exhausting the retry budget logs and continues; only a permanent error exits.

python -m bot.main --demo    # no token — watch it recover from a flaky API

Alerts you won't mute. Every page differs on every fetch — timestamps, view counters, session tokens — so it watches a CSS-targeted value, normalises known noise, and never mistakes a WAF challenge for a change.

python -m pagewatch --demo   # baseline → noise (silent) → real change → blocked

Multi-tenant FastAPI + SQLAlchemy 2.0. Tenant isolation is enforced by a session-level ORM event rather than per query — an event can't be forgotten by whoever adds a query next year. The suite includes a mutation check: one test queries through an unscoped session and asserts both tenants' rows are visible, proving the isolation tests can actually fail. Migrations tested in both directions against a seeded database.

MMO server architecture in C# / .NET 8. Login, Game World and Chat are separate assemblies — delete the World project and Chat still compiles. The demo shows the part that matters: the client asks to teleport to 9999,9999 and the server refuses and sends back the real position. Client-authoritative movement is the exploit most ready-made server packs ship with.

Merges spreadsheets that disagree, and reports the disagreements instead of silently picking a winner. Handles the quiet data-loss cases: "1,250.00" parsed as a number rather than becoming NaN, and whitespace stripped from text columns that a dtype == object check would skip under pandas 2.x.

Derives corporate email addresses from an organisation's naming convention, and is explicit about what it cannot know — a derived address is a candidate, not a verified mailbox.

Python · Rust · Go · TypeScript · JavaScript · Java · C++ · C# / .NET · PHP · Ruby · SQL · Bash · SystemVerilog

FastAPI · SQLAlchemy · Selenium · Linux · PostgreSQL · Docker · Maven · Cargo · CMake

Available for backend and systems work — automation, services, data plumbing, scraping and monitoring. Most at home in Python, but the table above is the honest answer to "can you work in X": each row is a defect found and fixed in someone else's codebase, not a line on a skills list. Send me a URL and I'll tell you whether it's extractable before you commit to anything.