Portfolio Manifest — Updated 2026-08-19
Principal Frontend Engineer
A from-scratch rebuild of NgRx's core state-management libraries, module by module: real, MIT-licensed source ported where fidelity to a battle-tested implementation matters, six classes deliberately redesigned where the original violates its own interface — not a toy demo, and not a rewrite for its own sake either.
The harder problem, on purpose
Writing a demo app from scratch means there's no existing architecture to evaluate, defend, or push back on — nothing to actually decide. This rebuild is the opposite exercise: recreate NgRx, Angular's dominant state-management ecosystem, module by module from the real source, and demonstrate the harder skill — knowing which parts of a mature codebase to port faithfully because they're already right, and which to challenge because they aren't, with the reasoning written down the way it would need to be defended in a real architecture review.
Composition over inheritance — six classes, three audit passes, complete 2026-08-06
The real NgRx Store, ActionsSubject,
ReducerManager, State,
ScannedActionsSubject, and EffectSources all
extend RxJS's Observable/Subject types directly
— a genuine Interface Segregation violation, not a style nitpick. Every
consumer inherits the entire RxJS operator surface (pipe,
lift, toPromise, ...) when each class's actual
contract is far narrower. Store even has to override
lift() in the real source purely to stop RxJS's own internal
machinery from silently downgrading a Store back to a plain
Observable mid-chain — direct evidence the fit is wrong, not
a feature of it.
Each class now holds its RxJS subject privately instead of extending it, exposing only the surface its actual contract needs. No override-the-base-class special cases left behind — the symptom that flagged the problem in the first place is gone, not patched over.
Store losing the Observer interface is a real behavior
change: ~40 call sites across 6 spec files rewritten, 2 tests deleted
outright because the capability they tested no longer exists to test.
Named in
docs/architecture.md, not glossed over.
CodeQL findings, fixed on a branch, landed through an actual Pull Request
10 CodeQL findings fixed in total across this repo's life — the two below
are the original pair, real pre-existing vulnerabilities in ported Angular
CLI source (Copyright Google Inc. still in the file header),
found by CodeQL and not introduced by this repo, fixed here regardless and
landed through
PR #21
rather than a direct-to-main shortcut. The other 8 are the
same two finding classes recurring as more modules were added — documented
below rather than folded silently into the headline count.
.* with no ^ anchor, forcing an O(n) retry
from every character position on non-matching input, O(n²) total.
Replaced with plain string methods
(split/indexOf/lastIndexOf),
immune by construction rather than just a safer regex.
json[type][pkg] = version with
unvalidated keys; a "__proto__" value would reassign
the object's prototype instead of adding a normal property. Fixed
with an explicit key guard.
schematics-core/utility/package.ts at the time it was
added, inheriting the still-vulnerable code. Closed alongside the
rewrite that finally satisfied CodeQL's own sanitizer recognition
(see the note below) — all 4 duplicate copies fixed in the same
commit, plus a real, separately-caught CI reliability bug
(undeclared Nx task dependencies letting a build step race ahead of
its own output).
normalizeRoot, found once the data module
was added. Replaced with an index-based manual scan, the same
"immune by construction" approach as finding 01.
Disclosed, not hidden: the first prototype-pollution fix
was functionally correct but used a Set.has() guard —
CodeQL's own sanitizer recognition doesn't trace booleans returned from
Set.has()/Array.includes() back to the guarded
key, so re-scanning still flagged it as open. Rewritten to direct
string-literal equality checks, the pattern CodeQL's own query actually
recognizes, rather than arguing the tool was wrong.
Real builds, real CI, stress-tested rather than assumed reliable
Every module port requires a real ng-packagr build, a real
test run, and a real lint pass before being called done — then the same
three gates again on GitHub Actions infrastructure this repo doesn't
control. Two intermittent CI failures traced to undeclared Nx task
dependencies weren't called fixed on the strength of one clean run; the
fix was verified by deliberately wiping the cache and stress-testing at
--parallel=4 until the race stopped reproducing.
Across all 13 ported modules, real assertions against real behavior — not snapshot tests, not compilation-only checks passing for the wrong reason.
A full interactive test report plus a per-module composition chart,
deployed to
GitHub Pages
on every push to main — checkable against the live
repository, not a static screenshot.
Where the interesting decisions actually happened
A live-deployed test report flagged roughly 100 tests as "slow." The cheap fix was obvious — raise the reporting threshold — and it was implemented wrong twice before it even took effect. Once genuinely applied, the number barely moved. That non-result was the actual signal: rather than call the config change "done," it pointed at a real bug — a test helper spinning up four full Angular schematic generators fresh before every single test instead of once per file. Fixed at the source: an 18×/4.5× real speedup, not a hidden threshold. Confident-looking config changes and an actually correct fix aren't always the same thing — worth telling apart, and worth writing down in todo.md when they diverge.