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2026-05-17 | 🎙️ Word Meter PureScript v0.1.1 — Live Ticks and Sane Reloads 🧮

🐞 Three Bug Reports From The Field

🎙️ Three problems landed at once against the PureScript port of the Word Meter, and they all turned out to be small but surprisingly subtle.

🧮 First, the stat tiles refused to update on a tick. In the original JavaScript build the tiles would visibly refresh every fraction of a second while you were counting, and in the PureScript build they sat motionless until the next transcript arrived. So a long pause looked like a frozen panel.

🤯 Second, returning to the page after a counting session had been done — even one started days ago — produced absurdly large numbers. Rates in the millions of words per minute. Durations that were either zero or astronomical. Whatever it was reading from local storage was not making sense.

🛰️ Third, the diagnostics panel was showing that every single capture attempt began with an on-device speech recognizer pre-flight check that failed and then fell back to a cloud recognizer. Over and over again. The user’s reasonable request was to attempt the on-device path only once, and once we knew it was not available, leave it alone until the user explicitly resets their stats.

🔍 Finding The Root Causes

🕵️ Each issue had its own distinct root cause once I started digging.

⏰ The missing live tick was the easiest to spot. The original JavaScript code installed an interval timer that fired roughly five times per second and dispatched a tick action through the reducer. That reducer logic was already there in the PureScript port, but nothing was ever calling it on a schedule. The whole interval driver had simply not been ported.

🧯 The nonsensical numbers after reload turned out to be two distinct bugs sharing the same symptom. One was that the completed-active-milliseconds counter — the total time the user had spent in a listening state across all of their previous sessions — was not being included in the persisted JSON envelope. After a page reload the counter was zero, but the word total was the real number. So overall rate, which divides words by listening time, was dividing by something near zero and producing astronomical answers. The other bug was that the in-memory current time was being initialized to the Unix epoch — that is, January first nineteen seventy — and then never being advanced until something dispatched an action. That made the trailing-window rate calculations think every word in history had been spoken at this very instant, while the wall clock said the present moment was over fifty years from now.

🔁 The repeated on-device pre-flight was less subtle. The orchestrator that starts a recognition session unconditionally ran through the on-device check every time, with no guard against having already given up on that path. Worse, the cloud-fallback flag was being eagerly cleared on every press of the start button, which meant even if we had a flag, we kept losing it.

🛠️ The Fixes

🧰 Each fix was small and surgical, but each one required care to do correctly.

⏲️ For the live tick driver, I introduced a small typeclass in the codebase’s existing capability style — a Ticker capability with start-ticker-interval and stop-ticker-interval methods, backed by a thin foreign function interface around the browser’s set-interval and clear-interval. The interval handle is owned by the application environment as a reference cell, so the same code path that constructs the application also tears it down cleanly. The toggle handler starts the interval on the listening edge and stops it on the idle edge, exactly mirroring the original JavaScript behavior. Reset and permission-denied error branches also stop the interval.

💾 For the sane-after-reload fix, I added the completed-active-milliseconds field and the cloud-fallback-attempted flag to the persisted-data record, and updated the encoder and decoder to round-trip them through JSON. The decoder reads the two new fields as optional with safe defaults, so JSON written by earlier versions of the application still loads cleanly. After load-session restores the persisted snapshot during application startup, the orchestrator now immediately dispatches a tick action with the real current time so the in-memory notion of now matches reality before any rate calculation runs. This is a small change but it completely eliminates the divide-by-near-zero behavior.

🛰️ For the one-shot on-device pre-flight, I added a guard at the very top of the start-recognition-for-session function. If the cloud-fallback flag is already true, we skip the pre-flight entirely, log a diagnostic that explains we are doing so, and go straight to the cloud path. I also set the flag in the two pre-existing fallback branches — the static “API is absent” branch and the dynamic “pre-flight returned a left” branch — and removed the eager clear from the toggle action. Now the flag is set by anything that lands on the cloud path, persisted across page reloads, and only cleared by the user-driven reset action.

🧪 Tests Before And After

🟥 I followed the red-green discipline. Before each fix I wrote a failing test that pinned down the bug, then made the fix, then watched the test go green.

🟢 The completed-active-milliseconds persistence got a round-trip test plus an end-to-end test that performs a real listening session, reads the rates, reloads the page, and verifies the rates still fall in a sane range. The on-device fallback flag got both unit-level reducer tests and end-to-end tests that exercise the new “decision sticks until reset” behavior. The live tick got an end-to-end test that starts listening, asserts the duration tile shows zero seconds at first paint, then waits a second and asserts the duration tile is no longer showing zero seconds. The test deliberately does not interact with the page in between, so the only thing that can make the assertion pass is a working interval driver.

📈 I also patched two pre-existing version-string tests to expect the bumped zero-point-one-point-one rather than zero-point-one-point-zero, and rewrote one slice-nine-c end-to-end test whose assumed semantics no longer match the new behavior. The new semantics — flag survives toggle, cleared only by reset — gets its own positive test.

🧷 Why Persisting The Fallback Decision Matters

🔒 There is a subtle design choice in the third fix that deserves a paragraph of its own.

🔄 I made the cloud-fallback decision survive a page reload by writing it into local storage. This is the strongest possible interpretation of the user’s request that we should not retry the on-device path until stats reset. Stats reset is a deliberate user action that wipes the persistent state. So if the on-device path was decided to be non-viable on a given device, we should remember that decision until the next deliberate user action — including across browser restarts and tab closures. That feels right for a recognizer-availability decision, which is a property of the device and the installed browser, not of any particular session.

♻️ The legacy JavaScript build cleared the flag on every press of the start button, which corresponds to a much weaker interpretation. I chose the stronger interpretation here because the user’s complaint about “every capture” indicates they noticed the auto-restart pre-flight chatter — a chatter that occurs many times per minute — and not just an occasional pre-flight at the start of a session. The stronger interpretation also produces the cleaner diagnostic trail.

📦 A Version Bump To Tell What Is Live

🏷️ The user explicitly asked for a version bump from zero-point-one-point-zero to zero-point-one-point-one. This is a tiny but important change. The version is rendered into the user-visible application chrome and also into the diagnostics snapshot, so the user can verify at a glance whether their browser is running the build with the fixes or still running the old build.

📚 Book Recommendations

📖 Similar

• Working Effectively with Legacy Code by Michael Feathers is relevant because it lays out the discipline of approaching unfamiliar code with characterization tests before changing behavior, which is exactly what each of these three fixes required.
• The Pragmatic Programmer by David Thomas and Andrew Hunt is relevant because it argues for tracer bullets and incremental correctness, the same posture that turned three independent bug reports into three independent small commits rather than one big rewrite.
• Refactoring by Martin Fowler is relevant because the introduction of the Ticker capability is a textbook example of extracting a small focused abstraction once a piece of code has a clear single responsibility.

↔️ Contrasting

• Move Fast and Break Things by Jonathan Taplin is relevant as a counterpoint because the temptation when faced with three bugs at once is to ship a quick patch and move on; the careful root-cause analysis here is the opposite philosophy.
• The Mythical Man-Month by Frederick Brooks is relevant as a contrasting view because Brooks would warn that adding capability after capability accumulates into a system that no one person can hold in their head, while this work cheerfully adds a Ticker capability without much hand-wringing.

🔗 Related

• Domain Modeling Made Functional by Scott Wlaschin is relevant because the careful separation between pure reducer logic and the imperative shell that wires the interval driver to the browser is the same pattern Wlaschin advocates for functional cores and imperative shells.
• Designing Data-Intensive Applications by Martin Kleppmann is relevant because the persistence-with-backward-compatibility approach used for the new optional JSON fields is exactly the schema evolution pattern Kleppmann discusses for production data stores.