---
title: "Capture a daily log entry"
description: "Record a measurement in three taps, one-handed, without leaving the screen the person was already on."
url: "https://opsinjs.pensievelabs.org/recipes/daily-log-entry"
source: "https://opsinjs.pensievelabs.org/recipes/daily-log-entry.md"
section: "Recipes"
kind: "recipe"
evidence: "opinion"
reviewed: "2026-09-20"
reviewer: "engineering"
implements: ["log-sheet", "reading-input", "button", "field", "sheet"]
---
> Elements written as `` below are opsinjs documentation
> components. Their attributes are the content: the values they render are
> generated from `tokens/*.json` and `registry/catalogue.ts` and are
> published separately at https://opsinjs.pensievelabs.org/r/index.json and under the Reference
> section.
> Nothing is missing from this page. The data simply does not live in
> the prose.
## The task [#the-task]
Somebody has to record the same thing every day: a blood pressure reading, a
blood glucose value, a weight, a dose taken, how they slept. They will do it while
holding a cup, on a bus, half-asleep, for months. The design constraint is not
elegance; it is that the entry must cost so little that it still happens in week
twelve.
Friction here is not a usability nuisance, it is a data-quality problem. An entry
flow that takes eight taps produces a log with gaps in it, and a log with gaps is
a trend you cannot draw and a summary you cannot show a clinician. Every extra
decision you put in the way removes data from the rest of the product.
The target is three taps from the screen the person was on: open, enter, save.
## What you need [#what-you-need]
The components this entry flow composes are all `shipped`: the code exists and
installs, the API may change in any release, and
none of it has been through an accessibility or a clinical review. Every part
below installs, the stepped and segmented
entry in the last row included. Composing them into the flow is still yours to do.
| Part | Component | Status | What it does here |
| ------------------- | ------------------------------------------------------------------------------------------------------- | -------------------------------- | ----------------------------------------------------------------- |
| The capture surface | [LogSheet](../components/log-sheet.mdx) | | Low-friction bottom sheet, sized to the entry. |
| The number entry | [ReadingInput](../components/reading-input.mdx) | | Numeric input with a unit switch and a plausibility warning. |
| The sheet mechanics | [Sheet](../components/sheet.mdx) | | Detents, drag, keyboard-safe insets, focus return. |
| Label and error | [Field](../components/field.mdx) | | The label/control/hint/error composition every input sits inside. |
| Save and undo | [Button](../components/button.mdx) | | The primary action, within thumb reach. |
| The confirmation | [Value](../components/value.mdx) · [RelativeTime](../components/relative-time.mdx) | | Shows what was saved, where it will live. |
| First run | [EmptyState](../components/empty-state.mdx) | | Before there is anything logged. |
| Stepped entry | [NumberField](../components/number-field.mdx) · [SegmentedControl](../components/segmented-control.mdx) | | A stepped or segmented entry, when a free number is not the fit. |
Tokens, by family:
| Family | Where it applies | Reference |
| -------------------- | ---------------------------------------------------------------- | ----------------------------------------------------------------- |
| Space scale | Target size, separation, thumb-reach zone | [Density and touch](../foundations/space/density-and-touch.mdx) |
| Material rung | The sheet's rung above the page, and its opaque fallback | [Choosing a layer](../foundations/materials/choosing-a-layer.mdx) |
| Motion | Sheet presentation and dismissal, and their reduced-motion forms | [Reduced motion](../foundations/motion/reduced-motion.mdx) |
| `--opsin-category-*` | The category of the thing being logged, as identity only | [Category identity](../health/category-identity.mdx) |
## Build it [#build-it]
### Put the entry point where the person already is [#put-the-entry-point-where-the-person-already-is]
The log action belongs on the surface that shows the metric, such as the tile
or the detail screen. It does not belong behind a plus button in a navigation
bar three levels away.
The best entry point is the thing the person is already looking at when they
remember they need to log.
Whatever you choose, it is one target, at least 44pt, and it is in the lower
third of the screen where a thumb reaches without a grip change.
### Present a sheet, not a screen [#present-a-sheet-not-a-screen]
A full-screen form says *this is a task*. A sheet says *this is a moment*. The
sheet keeps the context visible behind it, which both reassures the person that
they have not lost their place and makes dismissal obviously safe.
Size the sheet to its content with a detent, not to an arbitrary half-screen. The
primary control sits above the keyboard, and the sheet respects the keyboard-safe
inset so the save button is never underneath the keyboard.
[Sheet](../components/sheet.mdx) owns that mechanic.
### Default everything you legitimately can [#default-everything-you-legitimately-can]
Every default you supply removes a decision:
* **Time**: now. Editable, because a person logs a reading twenty minutes late.
* **Unit**: whatever they used last. Never make somebody re-pick their own unit
system daily.
* **Category and metric**: implied by the entry point they used.
Do not default **the measurement itself**. Pre-filling yesterday's value is
tempting because it is fast, and it is exactly how a log fills with numbers
nobody measured. A blank field is honest.
### Make the number easy to type and hard to get wrong [#make-the-number-easy-to-type-and-hard-to-get-wrong]
[ReadingInput](../components/reading-input.mdx) is the specialist here, and it has
three jobs beyond being a text box:
* **The right keyboard**, first time. A decimal measurement needs a decimal pad,
not a spelling keyboard with a numbers layer.
* **The unit beside the field**, switchable, with the value converting when it is
switched. Because switching it changes the number without anybody typing, the
product announces the conversion. See [Unit systems](../health/unit-systems.mdx).
* **A plausibility warning, not a block.** A body temperature of 96 is implausible
in °C and ordinary in °F; a systolic of 400 is almost certainly a typo. Say so,
softly, and let it be saved anyway. A hard maximum means the one person whose
real reading is out of your range cannot record it, and their reading is the one
that mattered.
### Confirm in place, without a dialog [#confirm-in-place-without-a-dialog]
On save, the sheet dismisses and the value appears where it will live from now
on, briefly distinguished so the eye finds it. That is the confirmation. A modal
saying "Saved!" costs a tap to dismiss and tells the person less than seeing the
number in position.
### Offer undo instead of asking "are you sure?" [#offer-undo-instead-of-asking-are-you-sure]
Confirmation dialogs tax every correct action to prevent a rare incorrect one.
Save immediately and offer undo for a short window. Undo restores the previous
state exactly, including the case where the entry replaced an earlier value for
the same slot.
Deletion of a saved reading is a different matter and may confirm. A deleted
measurement cannot be re-measured.
### Handle the second entry of the day [#handle-the-second-entry-of-the-day]
The most-missed case. If a value already exists for this slot, decide in advance
whether the new entry replaces it, sits beside it, or is refused, and say which
before the person types. Several readings a day is normal for glucose and unusual
for weight, so this is per metric, not global.
## The copy [#the-copy]
Labels are questions, in the reader's words, with the unit in the label and
repeated beside the field.
* **Sheet title** is the thing being logged: "Blood pressure".
* **Field label** is "Systolic (top number)". The parenthetical is not
clutter; it is the difference between a correct entry and a transposed one.
* **Primary action** is the verb for what happens: "Save reading", not "OK",
"Done" or "Submit".
* **Plausibility warning** describes and asks, never accuses: "That is much
higher than your usual readings. Check the number, or save it anyway."
* **Confirmation** uses no words at all, if the value is visible in place.
A field labelled "Systolic (top number)" showing "120 mmHg", with the unit
beside the field and a decimal keypad already open.
"SYS" with no unit, a spelling keyboard, and a validation message reading
"Invalid input". None of those tell the person what to type or what went
wrong.
Error text says what to do, not what happened:
[Error and empty messages](../content/error-and-empty-messages.mdx). "Enter a
number between 30 and 300" is help; "Invalid value" is a shrug.
## Get it right [#get-it-right]
**Safety**
* No measurement is ever pre-filled from a previous entry.
* A plausibility warning never silently discards or corrects a value. The person's
number is their number.
* The time recorded is the time of measurement, and the person can change it.
Include the time zone; a reading logged while travelling must not move a day.
* The unit is stored with the value, or the value is converted to a canonical unit
on the way in and the original preserved. A stored number with an implicit unit
is a future incident.
* Logging on behalf of somebody else must be visibly distinct, or attributed
readings will end up on the wrong person's chart. The person logging might be
a carer or a parent.
**Accessibility**
* Every target clears 44pt with real separation, and the primary control is
reachable one-handed. See
[Target size and motor accessibility](../accessibility/target-size-and-motor.mdx).
* Focus moves into the sheet on open, is trapped while it is modal, and returns
to the control that opened it on dismissal.
[Keyboard and focus](../accessibility/keyboard-and-focus.mdx) specifies that
contract.
* The sheet is dismissible from the keyboard with Escape, not only by
dragging.
* The save is announced politely; the undo affordance is reachable by keyboard for
as long as it is available. An undo that only a mouse can reach is not an undo.
* Switching the unit converts the number on screen without anybody typing, so the
product routes `ReadingInputChange.effectText` through the same polite announcer
it uses for the save, on every change where `effectText` is not null.
[ReadingInput](../components/reading-input.mdx) hands you the exact sentence and
deliberately mounts no live region of its own, so if the product stays silent a
reader hears only the new unit and saves a number they were never told about.
[Screen readers](../accessibility/screen-readers.mdx) has the announcement rules.
* Validation is announced when it appears and is associated with its field, so it
is heard rather than only seen.
[Screen readers](../accessibility/screen-readers.mdx) covers the announcement.
* Typed input survives rotation, backgrounding and a keyboard dismissal. Losing a
half-typed reading is the fastest way to end a logging habit.
* At 200% text the sheet scrolls; the primary control stays reachable and never
moves under the keyboard.
## Variations [#variations]
**Several fields in one reading.** Blood pressure is systolic, diastolic and
often pulse: one reading, one save, one timestamp. Do not split it into three
entries. A systolic without its diastolic is not usable.
**A value on a scale rather than a number.** Pain, mood, fatigue.
[ScaleInput](../components/scale-input.mdx) now ships for this. Prefer its
labelled set of options over a free slider, because a slider invites false
precision on a scale that has none.
**A dose or a medication taken.** [DoseTracker](../components/dose-tracker.mdx)
now ships. Adherence data is more sensitive than most measurements and
needs an explicit consent conversation. See
[Ask for consent before collecting](./consent-before-collection.mdx).
**Backfilling several days at once.** A different task with a different shape,
and a real one after a holiday. It is a list of dates, not a repeated sheet.
**Automatic capture from a device.** Then there is no entry flow, and a different
problem: the reading arrives with provenance, and the display has to be able to
say which device produced it and how accurate that device is.
## Related [#related]
* **[Daily logging](../patterns/daily-logging.mdx)** covers the same task at
flow scale: reminders, streaks, and what to do about a missed day.
* **[LogSheet](../components/log-sheet.mdx)** and
**[ReadingInput](../components/reading-input.mdx)** are the two component
specifications this recipe assembles.
* **[Daily log screen](../screens/daily-log-screen.mdx)** is the whole surface
this entry flow lives on.