A minimal, local-first log of what you did and exactly when — to the second.

SecondLog is a single-screen task dashboard. You add a task with its start and end time, and it appears as a row in a calm, dark list you can edit, delete, and export. There is no timer to start, no account to create, and no data leaving your machine.

• Quick capture in the title field — type one line like wrote spec 9:15-10:40 or email Sam yesterday 14:00-14:20 and the date/time fields are filled from it. Add a description in ${...}, e.g. wrote spec ${drafted the API section} 9:15-10:40. Add today, yesterday, or a YYYY-MM-DD date; ranges crossing midnight roll over to the next day. Without a time range, the title, description, and date/time fields behave exactly as before.
• Log a task — a title, an optional description, and a start and end date + time, precise to the second.
• Read the list — every entry on one page, newest first, with dates and 12-hour times (AM/PM) in tabular monospace.
• Fix mistakes — edit any row inline (or cancel), delete a row.
• Keep it — entries persist in the browser's localStorage and survive a refresh.
• Take it out — export everything as JSON or CSV from the Export menu.

Deliberately not included: no accounts, no projects/tags/clients, no live stopwatch, no charts or reports, no server. A log that stays exact is a log that stays small.

Requires Node.js 20.9 or newer.

npm install
npm run dev

Open http://127.0.0.1:3000. The server is bound to the loopback address, so it is reachable from this machine only.

npm run build   # production build
npm run start   # serve the production build
npm run lint    # eslint

localStorage is per-origin, and http://127.0.0.1:3000 and http://localhost:3000 are different origins — stay on one URL, or the log will look empty on the other. Use Export → JSON to move entries across.

The whole app is one client-rendered page. The interesting logic lives in app/lib/entries.ts:

• combineDateAndTime(dateStr, timeStr) turns a YYYY-MM-DD date plus an HH:MM:SS time into an ISO timestamp, and rejects values that don't round-trip (e.g. 2026-02-30).
• parseQuickEntry(input) pulls a title, an optional ${...} description, an optional relative or ISO date, and a clock range (9:15-10:40, 9am-9:15am, 14:00 to 14:20) out of one line, returning a validated start/end pair. The add form runs it only when the title contains a clock range; otherwise parseTitleShortcut just lifts ${...} into the description.
• isValidRange(startIso, endIso) enforces that an entry can't end before it starts — crossing midnight is fine, since the end has its own date.
• formatTime12(iso) / formatDateShort(iso) render the start and end in the list; dateFromIso(iso) and timeFromIso(iso) feed the edit form.
• toCsv(entries) renders the list as CSV, quoting any cell that contains a comma, quote, or newline.

Entries are stored as { id, title, description, startDate, endDate } under the single localStorage key secondlog.entries. page.tsx holds them in React state and writes the full array back to storage on every add, edit, and delete; a read failure is treated as an empty list rather than an error. Nothing is sent anywhere — there is no backend.

The app is local by construction, and that is enforced rather than promised:

• No network at runtime. There is no fetch, XMLHttpRequest, WebSocket, EventSource, or beacon anywhere in app/; fonts are self-hosted at build time.
• Loopback only. The server binds 127.0.0.1, so it is not reachable from the network.
• Your entries never reach the server. They live in localStorage and are read back by the browser.
• No accounts, cookies, analytics, or third-party scripts, and a CSP of default-src 'self' would block them if one were added.
• Security headers (X-Frame-Options, nosniff, Referrer-Policy, Permissions-Policy, and the CSP) are set in next.config.ts.

SECURITY.md covers the guarantees, what they do not protect against, and how to verify them. docs/ARCHITECTURE.md covers the component map, the data flow, and the trust boundary.

app/
├── layout.tsx              # Root layout, fonts, dark theme, metadata
├── page.tsx                # The single dashboard: form + list (client component)
├── globals.css             # Tailwind base styles
├── lib/entries.ts          # Entry type, validation, formatting, CSV, storage helpers
└── components/
    ├── AddTaskForm.tsx     # Title (one-line syntax), description, start/end, "Log task"
    ├── TaskList.tsx        # Rows, inline edit, delete, empty state
    ├── ExportMenu.tsx      # JSON / CSV export
    └── icons.tsx           # Inline SVG icons
docs/architecture.md        # How the app is put together and why it cannot phone home
devpost/                    # Planning documents: scope, PRD, spec, build checklist, app map

Built with Next.js (App Router), React, TypeScript, and Tailwind CSS.