fix(push): "der kommer ikke nogen" kunne ikke besvares

Alt om det var usynligt. Indstillingssiden sagde "til for denne enhed", så snart der fandtes et abonnement — også når hver eneste push blev afvist. Og en afvist push gik i en logline på **Debug**, som ikke skrives på en instans, der kører på standardniveau. Så en levering, der fejler lydløst, og en levering, der aldrig sker, så ens ud, og forskellen er hele diagnosen. Tre forskellige problemer havde ét udseende: browseren tilmeldte sig aldrig, tjenesten afviste den, eller der var ikke noget forfaldent endnu. **En prøveknap** under Indstillinger → Notifikationer sender én notifikation gennem den rigtige rute — ikke en genvej, så det, den beviser, er det, der faktisk skal virke — og siger hvad hver enhed gjorde ved den. Kom den ikke frem, og afviste ingen den, står der, at det så er browseren eller styresystemet, der holder den tilbage. Nu peger svaret på ét af de tre steder. Loglinjen er hævet fra Debug til Warn. Det var den ene linje, der ville have sagt hvorfor. Teksten kommer fra klienten, fordi ordbøgerne gør. En server, der bærer sin egen kopi af "det her er en prøve", bærer den på ét sprog. **Og en lækage, prøven fandt.** Go pakker en transportfejl som `*url.Error`, og dens tekst er `Post "https://fcm.googleapis.com/fcm/send/dQw4…": dial tcp: …` — hele endepunktet, som er den legitimation, push-tjenesten udstedte til den enhed. Den var på vej ud i svaret, i loglinjen og i ethvert skærmbillede af nogen af dem. Prøven var skrevet for at bevise, at kun værten blev nævnt, og det var sådan den blev fundet. Fejlen pakkes ud, og adressen skrubbes bagefter alligevel: den næste fejltype, der bærer den med, kommer ikke med en advarsel. Co-Authored-By: Claude Opus 5 <[email protected]>
feat(tasks): tid på en opgave, og et træk i kalenderen sætter den
2026-08-20 20:41:33 +02:00 · 2026-08-20 20:29:03 +02:00 · 2026-08-20 20:02:59 +02:00
13 changed files with 980 additions and 24 deletions
@@ -0,0 +1,437 @@
+# Notes, as verdande builds them
+
+A description of one working notes system: the data model, the syntax, the search,
+the rendering contract, the import and export formats, and — more useful than any
+of it — the decisions that look arbitrary until you know what they cost.
+
+It is written to be lifted into another program. Nothing here depends on Go,
+SQLite or Svelte except where it says so; where an answer was forced by the tool,
+that is called out so you can pick a different one on purpose rather than by
+accident.
+
+---
+
+## Read this part first: what to ask before you build
+
+**This document is not a drop-in. It describes a notes system that lives inside a
+task app with projects, roles, a trash and a search box, and about a third of its
+design is inherited from that.** Lifting it into a program with different
+surroundings without deciding which parts to keep produces something that works
+for a week and then fights you.
+
+**If you are an assistant working from this file: ask these questions and get
+answers before writing code.** Do not guess a default. Each one changes what you
+build, not just how you build it.
+
+### About the surroundings
+
+1. **Does the host app already have a place to file things** — projects, folders,
+   notebooks, tags? verdande deliberately gave notes no hierarchy of their own and
+   filed them under the projects that already existed. If your app has nothing,
+   you need an answer for where a note lives, and "a folder tree" is the expensive
+   one.
+2. **Is there more than one person?** Sharing, roles and "who wrote this" run
+   through the whole model below. Single-user changes the schema and removes about
+   half the permission surface.
+3. **Is there already a trash, and does it expire?** Notes lean on one. Without
+   it, deleting is either permanent or you are building a trash.
+4. **Is there an existing full-text index?** The search here is FTS5-shaped. On
+   Postgres it is `tsvector`, on a client-side app it is probably a scan, and the
+   ranking section below changes accordingly.
+
+### About the notes themselves
+
+5. **Markdown, rich text, or blocks?** verdande stores Markdown and renders it.
+   That decision is defended below; it is also the one that most constrains
+   everything else.
+6. **Is the first line the title, or is there a title field?** Both work. Deriving
+   it means one less thing to keep in step and one less thing a person can leave
+   blank, and it forces the rule "the first line is a heading" on the editor.
+7. **What links to what?** `#project`, `[[note]]` and task references exist here
+   because the app has projects and tasks. Yours may have none of them, or others.
+8. **Do notes carry files?** Attachments bring content-type handling, a store, an
+   authorisation path and an XSS surface. Skipping them is a legitimate answer.
+
+### About scale and language
+
+9. **How many notes, realistically?** Several choices below flip at around ten
+   thousand: the list payload, the search fallback, rendering the whole list.
+10. **Which languages?** The folding described under *Search* is Danish. Every
+    language has its own version of that problem and the generic answer (strip
+    diacritics) is wrong for several of them.
+11. **Where does the text end up besides the screen?** Search indexes, AI
+    features, exports and backups each read it. Plaintext makes all of them cheap
+    and makes a stolen backup expensive — see *What is still open*.
+
+### About integration, specifically
+
+12. **Who owns the note's identity — you or the other system?** If notes will sync
+    with something else, ids and timestamps are the whole problem, and the
+    `updated_at` rule below becomes the first thing you have to change.
+13. **Is this a read of somebody else's notes, or the store of record?** A copy
+    needs conflict rules; a store of record needs export.
+14. **What happens to a note whose project, task or link target is deleted?**
+    Answered here as "the link goes dead and the note is untouched". If your host
+    app cascades instead, say so before the first delete.
+
+---
+
+## The shape of a note
+
+```
+id           an opaque string, unique
+project_id   nullable — where it is filed, or loose
+title        derived, never set by a caller
+body         Markdown, the whole note
+created_by   nullable — survives the account being deleted
+pinned       favourite; the list puts these first
+archived_at  nullable timestamp — put away, not thrown away
+deleted_at   nullable timestamp — the trash
+created_at
+updated_at
+```
+
+### Markdown in a column
+
+Not rich text, and not a format of our own.
+
+Export was a requirement before a line was written, and **if the stored form is
+the exported form there is no conversion left to lose anything in.** A note stays
+readable by any editor on the day the program is gone. It is also what makes
+search and anything an AI does over notes cheap: both read text.
+
+The cost is real and you should know it before choosing: everything the editor can
+do has to survive a round trip through Markdown, and anything Markdown cannot say,
+the editor must not offer. There is no place to hide a feature.
+
+### The title is the first line
+
+Always, and re-derived on every save — not "when it is empty".
+
+Derived once and then left alone, a title goes stale the moment somebody rewrites
+the opening of a note, and the list ends up calling a note by a name that is
+nowhere in it. **The column is a cache of the body, not a field beside it**, and no
+caller can set it, so every caller gets the same answer.
+
+This forces one editor rule: a new note opens on its title, and the first line is
+styled as a heading. Otherwise a note whose first line is a sentence is a note
+named by its first sentence.
+
+### Archive and trash are two different bits
+
+The trash says *this was a mistake, and in thirty days it is gone*. The archive
+says *this is finished, and I do not want to read past it.*
+
+A twelve-hundred-note import is exactly the case where most notes are worth
+keeping and almost none are worth looking at. Without an archive, the list is the
+whole archive forever, and finding this week's note means reading past a decade.
+
+Both are nullable timestamps rather than booleans: *when was this put away* answers
+questions a flag cannot, and it costs the same byte.
+
+---
+
+## Filing: no hierarchy of its own
+
+A note belongs to a project, or to nobody.
+
+The reasoning is worth repeating because it is easy to talk yourself out of:
+projects already exist, are already shared, already have roles, already have a
+trash. **A second hierarchy to file things in is one too many**, and a note filed
+under a project inherits every one of those answers instead of needing its own.
+
+- A note with a project: everybody who can read the project can read the note; an
+  editor can change it.
+- A note without one: the author's, and nobody else's.
+
+Sharing a note *is* filing it in a project. There is no access list of its own —
+a second way to give somebody access is a second place to get it wrong, and the
+two would disagree the day one of them changed.
+
+---
+
+## Links: three kinds, parsed out of the text
+
+The body is the truth. Links are an index over it, rebuilt on every save.
+
+| Syntax | Means | Notes |
+|---|---|---|
+| `#project` | a project | Same characters the task quick-add parser uses, on purpose |
+| `[[a note]]` | another note, by title | The spelling every note app has settled on |
+| `/opgave/<uuid>` or `task:<uuid>` | a task | What a link pasted out of the app carries |
+
+Patterns as used here:
+
+```
+project   (?:^|\s)#([\p{L}\p{N}_-]{1,64})
+note      \[\[([^\]\n]{1,200})\]\]
+task      (?:/opgave/|task:)([0-9a-fA-F-]{36})
+```
+
+Three decisions inside that table:
+
+- **`#Firma` in a note means the same project as `#Firma` in the task box.** Not a
+  second kind of tag that happens to look alike. That is the whole of "tag a note
+  and see it in the project".
+- **The link table is torn down and rebuilt on save, not diffed.** A body is small
+  and the set is small; a diff is a second description of the same fact, and it
+  can disagree with the text. That is the one thing this must never do.
+- **The target is not a foreign key.** A link to something deleted is a fact about
+  the note. It should read as a dead link rather than vanish, and it must not
+  block the delete.
+
+The index exists so the question can be asked **backwards**: *what has been written
+about this task?* Answering that by searching every note's prose would be too slow
+to leave a panel open on.
+
+---
+
+## Search
+
+Three layers, in the order they answer.
+
+### 1. Full-text, ranked
+
+FTS5 over `title`, `body` and a folded copy, with `unicode61 remove_diacritics 2`.
+
+Ranking is bm25 with **the title weighted ten times the body**. A word in the title
+is what the note is *about*; the same word once in a long body is a mention.
+
+This matters more than it sounds. Ordering by "last touched" is invisible with ten
+notes and useless with twelve hundred imported the same evening: searching "Tesla"
+answered with a note about nginx first and the note actually called "Tesla Model Y"
+second — which reads as a search that does not work, because from where the person
+is sitting it is one.
+
+### 2. Folding, for the language you are in
+
+`remove_diacritics` does not touch `ø`, `æ` or `å` — Unicode considers them
+letters in their own right, not accented forms. So a Dane cannot find "grøn" by
+typing "gron", which is how people type when the keyboard is not theirs.
+
+The answer here is a generated column carrying a transliterated copy:
+
+```
+ø,Ø → o     æ,Æ → ae     å,Å → aa
+```
+
+indexed alongside the body and **weighted the same as the body** — otherwise a
+folded match outranks an exact one.
+
+> **Ask, do not copy.** This mapping is Danish. German wants `ü → ue`, Swedish
+> disagrees with Danish about `ä`, and Turkish has a dotless `ı` that breaks
+> naive lowercasing entirely. Get the mapping from somebody who types the
+> language.
+
+### 3. A word inside a word
+
+An index is built of tokens, and a token is whatever the tokenizer decided was a
+word. `gamerule keepInventory true` is three of them, and the middle one is
+`keepinventory` — so a search for "keep inventory" asks for two words that are
+nowhere and gets nothing, while the note sits right there.
+
+A prefix query gets half of it: `keep*` matches, `inventory*` cannot, and the two
+are ANDed, so the half that works is thrown away by the half that cannot.
+
+**This is not exotic in a notes app.** A decade of notes is full of commands,
+identifiers and file names, and every one of them is several words the index
+thinks is one.
+
+So: the index answers first; when it has nothing, the text is read, and every term
+must appear somewhere in the note, in any word. A `LIKE '%term%'` over the folded
+column covers title, body and language folding at once.
+
+What it costs: a leading `%` cannot use an index, so it scans. At twelve hundred
+notes that is a few megabytes and a millisecond or two, and it only runs when the
+fast path already came back empty — which is exactly the search that was about to
+disappoint somebody. **At a hundred thousand notes it is the wrong shape**, and the
+answer then is a trigram index, not a bigger scan.
+
+It does not rank. There is no match to rank — that is the whole situation.
+
+---
+
+## The list, and why the body is empty in it
+
+A list showing a title and ninety characters of preview must not fetch whole
+notes. Twelve hundred notes came to 3.9 MB, of which 98 % was body nobody could
+see.
+
+The important half is *how* it is trimmed: **the body is emptied, not shortened.**
+
+A field called `body` holding a *piece* of the body is a trap. The editor opens
+it, the autosave pause writes it back, and the note is now cut down to its own
+excerpt — destroyed by nothing more than having been looked at. Send `preview` as
+its own field and leave `body` empty; the client sees the empty body and fetches
+the whole note.
+
+That costs one more separation, and it is not optional:
+
+> **Which row is selected and which note is loaded are two different things.**
+
+The editor loads its text when the note's id changes. Hand it the excerpt first
+and the whole note second and the id is the same both times — so the second one
+never renders, and somebody sits looking at a note that had a title a moment ago.
+
+Highlight the row immediately from the list; give the editor the note only when it
+is whole.
+
+Rendering cost, separately: with twelve hundred rows, first paint took 2.1 s. CSS
+`content-visibility: auto` with an intrinsic-size guess took it to 0.95 s with no
+virtual list, no scroll maths, and no list that can fall out of step with itself.
+Try that before building windowing.
+
+---
+
+## The editor contract
+
+Rich text on top, Markdown underneath, and a source view that shows the file.
+
+The supported subset — deliberately small, because everything in it has to survive
+the round trip:
+
+| Block | Markdown |
+|---|---|
+| Title | `# ` |
+| Heading | `## ` |
+| Subheading | `### ` |
+| Quote | `> ` |
+| Code block | ```` ``` ```` with an optional language |
+| Bullet and numbered lists | `- `, `1. `, nested |
+
+Inline: `**bold**`, `*italic*`, `~~strikethrough~~`, `` `code` ``, `<u>underline</u>`,
+and images as `![alt](url)`.
+
+Five rules that were each learned the hard way:
+
+1. **Every line becomes exactly one block.** Markdown normally joins consecutive
+   lines into a paragraph. Here it must not: the person typed a line and expects
+   to get it back, and an editor that silently reflows what somebody wrote is an
+   editor they stop trusting.
+2. **Load on id change, never while typing.** Writing to the editor's HTML puts
+   the caret back at the start, which mid-sentence is unusable.
+3. **One definition of what a code block contains.** A copy button inside the
+   `<pre>` and a syntax highlighter reading `textContent` will disagree, and the
+   difference ends up in the file — a click on "Copy" wrote the word *Copied* into
+   the code and the next save put it on disk. Have one function that says what a
+   block holds, used by the highlighter and the Markdown serialiser both.
+4. **A note that cannot be rendered must not take the pane with it.** One note
+   arriving in an unexpected shape threw inside the editor's reactive effect, and
+   from then on *no* note would open — the previous one just stayed on screen. Put
+   a guard around the render, fall back to showing the raw text, and let the rest
+   of the pane keep working.
+5. **Escaping between tags and escaping inside an attribute are different jobs.**
+   An escaper written for text between two tags handles `&`, `<`, `>` — and not
+   quotes, because between tags they are harmless. Inside an attribute they close
+   it. `![" onerror="alert(1)](…)` is the whole exploit.
+
+---
+
+## Attachments
+
+Images pasted or dragged into a note, stored content-addressed by hash, referenced
+from the body as ordinary Markdown images.
+
+The security shape, which is the part worth copying:
+
+- **Served as `application/octet-stream` with `nosniff` by default.** Attachments
+  are the one place a user supplies content another user opens. An uploaded SVG or
+  HTML file rendered inline runs its own script on your origin with the session
+  cookie attached.
+- **One exception, as a named allowlist:** a short list of raster image types
+  served inline as their exact type — `png`, `jpeg`, `gif`, `webp`, `avif`, `heic`.
+  A note carries its pictures in the text, and served as octet-stream every one of
+  them is a broken image.
+- **The list is named one type at a time, never matched on an `image/` prefix.**
+  The prefix lets `image/svg+xml` through, and an SVG is a document that can run
+  script.
+- **The stored path is checked against the files directory again at read time.** A
+  traversal that somehow got into the database must not become one that reads
+  `/etc/passwd`.
+- **Reaching an attachment follows the note, which follows its project.** Same
+  chain as everything else. Do not let a client hand you the parent id and take it
+  on trust.
+
+---
+
+## Import and export
+
+The same format both ways: **a zip of Markdown files**, one per note, with a YAML
+front matter block.
+
+```markdown
+---
+created: 2019-04-02T10:15:00Z
+modified: 2024-11-30T21:04:00Z
+---
+
+# Møde med Anders
+
+Han vil gerne have kaffe hver uge.
+```
+
+- `created` / `created_at` / `date` and `modified` / `updated` / `updated_at` are
+  all accepted on the way in. Obsidian and Bear write this block; so should you.
+- Images travel in the zip beside the notes, and the links in the text are
+  relative — **a note and its pictures must end up in the same archive**, which
+  matters the moment an export is split into parts.
+- File names collide: two notes called "Møde" are two notes, and a zip with one
+  entry twice is a zip that loses one.
+
+Limits that a real import taught, all of them cheap to add and expensive to omit:
+
+- A ceiling on the upload, on the number of entries, and on the **unpacked** size.
+  64 MB of zip expanded to 66 GB is a normal shape for an attack.
+- A per-file limit as well as a whole-archive budget: one enormous photograph and
+  ten thousand small ones are different attacks with the same ending.
+- The entry name is never used as a path. Store by hash; the name is only a key
+  for rewriting links.
+- **Count what you skip, and say so.** A note whose name contained an ellipsis was
+  dropped silently by a filter looking for `..` — one out of 1141, found only by
+  counting at both ends.
+
+### Timestamps on the way in
+
+An importer needs to write `created_at` and `updated_at` from the file, and the
+normal save path must refuse to let it.
+
+`updated_at` means *when did this program last write this note*. Let any caller set
+it and the column means whatever the last writer felt like. Give the importer its
+own narrow entry point instead, and say in the comment why it exists.
+
+Without those dates, a move of twelve hundred notes is a pile that was all written
+the same evening — and the order they were written in is half of what an archive
+is.
+
+---
+
+## What is still open here
+
+Written down because a specification that only lists what works is a specification
+that lies by omission.
+
+- **Note bodies are plaintext at rest.** They hold API keys and passwords, and
+  they are in every backup anybody can download. Encrypting them is bigger than it
+  sounds: the body is in the full-text index and the folded column is generated
+  from it, so both are a second plaintext copy in the same database. Encrypt and
+  both have to go, and search has to be rewritten to decrypt in application code —
+  fine at a thousand notes, a full scan per keystroke at ten thousand, at which
+  point the answer is a keyed index (an HMAC per word).
+- **Import never merges.** Every run creates new notes. Say so out loud in the UI.
+- **There is no sync.** Export and the API are the way out.
+
+---
+
+## A short list of the traps, for the person in a hurry
+
+1. A `body` field holding an excerpt will be saved over the real one.
+2. Selected row and loaded note are two different pieces of state.
+3. The title must be re-derived on every save or it goes stale.
+4. Diacritic stripping is not folding, and folding is language-specific.
+5. A tokenizer cannot see a word inside a word; decide what you do about it.
+6. An attachment served inline is a script on your origin unless you allowlist by
+   exact type and send `nosniff`.
+7. Escaping for text and escaping for attributes are different functions.
+8. One render failure must not be allowed to freeze the whole pane.
+9. An unpacked-size limit is not optional on an archive import.
+10. Let the importer set timestamps; let nobody else.
@@ -2079,6 +2079,53 @@ paths:
        "404": { $ref: "#/components/responses/NotFound" }
        "422": { $ref: "#/components/responses/Validation" }

+  /api/v1/push/test:
+    post:
+      tags: [notifications]
+      summary: Send one notification to your own devices, and say what happened.
+      description: |
+        The answer to "no notifications arrive". A push that a service refuses is
+        the ordinary failure — a stale subscription, a browser that revoked
+        permission without telling the server — and every one of them looks
+        exactly like silence from the outside.
+
+        It goes through the same path a real notification takes, so what it proves
+        is the thing that has to work. The title and body come from the caller
+        because the dictionaries live in the interface.
+      requestBody:
+        required: false
+        content:
+          application/json:
+            schema:
+              type: object
+              properties:
+                title: { type: string, maxLength: 200 }
+                body: { type: string, maxLength: 500 }
+      responses:
+        "200":
+          description: What each device did with it.
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  subscriptions:
+                    type: integer
+                    description: Devices registered for this account.
+                  sent:
+                    type: integer
+                  failed:
+                    type: array
+                    items:
+                      type: object
+                      properties:
+                        service:
+                          type: string
+                          description: The push service's host — never the endpoint, which is a credential.
+                        reason:
+                          type: string
+                          description: What the service said.
+
  /api/v1/sections/{sectionID}:
    parameters:
      - { name: sectionID, in: path, required: true, schema: { type: string } }
@@ -2,6 +2,7 @@ package httpapi

 import (
 	"encoding/json"
+	"fmt"
 	"io"
 	"net/http"
 	"net/url"
@@ -9,6 +10,7 @@ import (
 	"testing"

 	"github.com/kristianwind/verdande/internal/config"
+	"github.com/kristianwind/verdande/internal/store"
 )

 // --- MCP -----------------------------------------------------------------------------
@@ -1468,3 +1470,62 @@ func TestTheMailAddressCanBeRotated(t *testing.T) {
 		t.Error("the second rotation returned the same address")
 	}
 }
+
+// "Der kommer ingen notifikationer" må kunne besvares.
+//
+// Alt om det var usynligt: indstillingssiden sagde "til for denne enhed", så snart
+// der fandtes et abonnement, og en push, tjenesten afviste, gik i en Debug-linje,
+// som ikke skrives på en instans, der kører på standardniveau. Man kunne ikke
+// skelne "browseren tilmeldte sig aldrig" fra "tjenesten afviste den" fra "der er
+// ikke noget forfaldent endnu" — tre forskellige problemer med ét udseende.
+func TestATestNotificationSaysWhatHappenedToIt(t *testing.T) {
+	ts := newTestServer(t)
+	ts.bootstrap(t)
+
+	// Ingen enheder: svaret skal sige nul frem for at lade som om det gik godt.
+	resp, body := ts.do(t, "POST", "/api/v1/push/test", map[string]any{
+		"title": "Prøve", "body": "kom den frem?",
+	})
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("status %d, body %v", resp.StatusCode, body)
+	}
+	if body["subscriptions"] != float64(0) {
+		t.Errorf("subscriptions = %v uden tilmeldte enheder", body["subscriptions"])
+	}
+
+	// En enhed, der peger på en tjeneste, som ikke findes. Den skal komme tilbage
+	// som et navngivent afslag og ikke som tavshed.
+	user, err := ts.db.UserByEmail(t.Context(), "[email protected]")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := ts.db.SavePushSubscription(t.Context(), &store.PushSubscription{
+		UserID:   user.ID,
+		Endpoint: "https://push.example.invalid/abc",
+		P256dh:   "BEl62iUYgUivxIkv69yViEuiBIa-Ib9-SkvMeAtA3LFgDzkrxZJjSgSnfckjBJuBkr3qBUYIHBQFLXYp5Nksh8U",
+		Auth:     "aUZmY2xDS2FQUXJJVmJIeA",
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	_, body = ts.do(t, "POST", "/api/v1/push/test", map[string]any{"title": "Prøve"})
+	if body["subscriptions"] != float64(1) {
+		t.Fatalf("subscriptions = %v", body["subscriptions"])
+	}
+	failed, _ := body["failed"].([]any)
+	if len(failed) != 1 {
+		t.Fatalf("failed har %d poster, want 1 — afslaget blev slugt", len(failed))
+	}
+	first, _ := failed[0].(map[string]any)
+	if first["service"] != "push.example.invalid" {
+		t.Errorf("service = %v", first["service"])
+	}
+	if first["reason"] == "" || first["reason"] == nil {
+		t.Error("afslaget kom uden en grund")
+	}
+	// Og aldrig hele adressen: resten af den er den legitimation, tjenesten gav
+	// enheden, og den hører hverken i et svar, en log eller et skærmbillede.
+	if strings.Contains(fmt.Sprint(first), "/abc") {
+		t.Errorf("endepunktet lækkede med ud: %v", first)
+	}
+}
@@ -1,7 +1,9 @@
 package httpapi

 import (
+	"errors"
 	"net/http"
+	"net/url"
 	"strings"
 	"time"

@@ -106,18 +108,44 @@ func (s *Server) PushToUser(userID, title, body, projectID string) {
 	s.pushToUser(userID, title, body, projectID)
 }

-func (s *Server) pushToUser(userID, title, body, projectID string) {
+// pushOutcome is what happened, per device.
+//
+// It exists because "nothing arrives" was unanswerable. A push that a service
+// refuses is the ordinary failure here — a stale subscription, a VAPID subject the
+// service will not take, a browser that revoked permission without telling the
+// server — and every one of them looked exactly like silence.
+type pushOutcome struct {
+	Subscriptions int           `json:"subscriptions"`
+	Sent          int           `json:"sent"`
+	Failed        []pushFailure `json:"failed"`
+}
+
+// pushFailure names the service and quotes what it said.
+//
+// The host and not the endpoint: the rest of that URL is the credential the push
+// service issued for this device, and it does not belong in an answer, a log line
+// or a screenshot.
+type pushFailure struct {
+	Service string `json:"service"`
+	Reason  string `json:"reason"`
+}
+
+func (s *Server) pushToUser(userID, title, body, projectID string) pushOutcome {
 	ctx, cancel := contextWithBackgroundTimeout(30 * time.Second)
 	defer cancel()

+	var out pushOutcome
 	subs, err := s.db.ListPushSubscriptions(ctx, userID)
 	if err != nil || len(subs) == 0 {
-		return
+		return out
 	}
+	out.Subscriptions = len(subs)
+
 	public, private, err := s.vapidKeys(ctx)
 	if err != nil {
 		s.log.Warn("vapid keys", "err", err)
-		return
+		out.Failed = append(out.Failed, pushFailure{Service: "verdande", Reason: err.Error()})
+		return out
 	}

 	payload := push.Payload{Title: title, Body: body, URL: "/projekt/" + projectID}
@@ -128,13 +156,101 @@ func (s *Server) pushToUser(userID, title, body, projectID string) {
 			Public: public, Private: private, Subject: "mailto:" + s.cfg.SMTP.From,
 		})
 		if err == nil {
+			out.Sent++
 			continue
 		}
-		s.log.Debug("web push failed", "err", err, "endpoint", sub.Endpoint)
+		// Warn, not Debug.
+		//
+		// This was the one line that would have said why no notification ever
+		// arrived, and at Debug it is not printed on an instance running at the
+		// default level. A delivery that fails silently and a delivery that does
+		// not happen look the same from the outside, and the difference is the
+		// whole diagnosis.
+		reason := pushReason(sub.Endpoint, err)
+		s.log.Warn("web push refused", "reason", reason, "service", pushHost(sub.Endpoint), "user", userID)
+		out.Failed = append(out.Failed, pushFailure{
+			Service: pushHost(sub.Endpoint),
+			Reason:  reason,
+		})
 		if recErr := s.db.RecordPushFailure(ctx, sub.Endpoint, push.IsGone(err)); recErr != nil {
 			s.log.Warn("record push failure", "err", recErr)
 		}
 	}
+	return out
+}
+
+// pushReason is what went wrong, with the endpoint taken back out of it.
+//
+// Go wraps a transport failure as `*url.Error`, and its message is `Post
+// "https://fcm.googleapis.com/fcm/send/dQw4w9…": dial tcp: …` — the whole
+// endpoint, which is the credential the push service issued for that device. It
+// would have gone into the answer, the log line and any screenshot of either. A
+// test written to prove the host was reported instead is what found it.
+//
+// Unwrapped first, so the cause is what is quoted. Then the endpoint is scrubbed
+// anyway: the next error type to carry it will not come with a warning.
+func pushReason(endpoint string, err error) string {
+	var urlErr *url.Error
+	if errors.As(err, &urlErr) && urlErr.Err != nil {
+		err = urlErr.Err
+	}
+	reason := err.Error()
+	if endpoint != "" {
+		reason = strings.ReplaceAll(reason, endpoint, pushHost(endpoint))
+	}
+	return reason
+}
+
+// pushHost is the service an endpoint belongs to, and nothing else from it.
+func pushHost(endpoint string) string {
+	u, err := url.Parse(endpoint)
+	if err != nil || u.Host == "" {
+		return "ukendt"
+	}
+	return u.Host
+}
+
+// handlePushTest sends one notification to this account's devices and says what
+// happened to it.
+//
+// Reported as "der kommer ikke nogen". Everything about that was invisible: the
+// settings page said "on for this device" as soon as a subscription existed, and a
+// refusal from the push service went into a Debug line nobody sees. There was no
+// way to tell "the browser never subscribed" from "the service refused it" from
+// "nothing has come due yet" — three different problems with one appearance.
+//
+// It goes through the same path as a real notification rather than a shortcut, so
+// what it proves is the thing that actually has to work.
+//
+// The words come from the client, which is where the dictionaries are. A server
+// that carries its own copy of "This is a test" carries it in one language, and
+// this one deliberately keeps its prose in the interface — see
+// `internal/i18n`. The text is only ever shown back to the person who asked for
+// it, on their own devices.
+func (s *Server) handlePushTest(w http.ResponseWriter, r *http.Request) {
+	var req struct {
+		Title string `json:"title"`
+		Body  string `json:"body"`
+	}
+	if err := decodeJSON(w, r, &req); err != nil {
+		return
+	}
+	title := strings.TrimSpace(req.Title)
+	if title == "" {
+		title = "verdande"
+	}
+	// Bounded: this is written into a notification on somebody's lock screen, and
+	// a megabyte of title is not a notification.
+	if len(title) > 200 {
+		title = title[:200]
+	}
+	body := strings.TrimSpace(req.Body)
+	if len(body) > 500 {
+		body = body[:500]
+	}
+
+	user := userFrom(r.Context())
+	writeJSON(w, http.StatusOK, s.pushToUser(user.ID, title, body, ""))
 }

 func (s *Server) vapidKeys(ctx contextLike) (string, string, error) {
@@ -295,6 +295,9 @@ func New(cfg *config.Config, db *store.DB, log *slog.Logger, web fs.FS) *Server
 				r.Get("/key", s.handlePushKey)
 				r.Post("/subscribe", s.handleSubscribePush)
 				r.Post("/unsubscribe", s.handleUnsubscribePush)
+				// One notification, to this account's own devices, reporting what
+				// each of them did with it. The answer to "der kommer ikke nogen".
+				r.Post("/test", s.handlePushTest)
 			})

 			r.Route("/attachments/{attachmentID}", func(r chi.Router) {
@@ -983,11 +983,11 @@ test('en opgave kan trækkes hen over et månedsskifte i uge-visningen', async (
 	// slipper der, hvor man kan se, man slipper.
 	await chip.dragTo(page.locator(`[data-date="${to}"]`), { targetPosition: { x: 30, y: 20 } });

-	// Sluppet på timesøjlen, landet i heldagsbåndet — og det er det rigtige sted.
-	// Et træk hen på en dag flytter datoen og sætter ikke et klokkeslæt, så opgaven
-	// har ingen tid at stå ved. `data-allday` er den anden halvdel af dagen: siden
-	// ugen blev et døgn, er en dag to kasser, og en prøve skal sige hvilken.
-	await expect(page.locator(`[data-allday="${to}"]`).getByText('skifte dæk')).toBeVisible();
+	// Landet i timesøjlen med et klokkeslæt: hvor på døgnet man slap, *er* tiden.
+	// Sluppet tyve pixels nede i en søjle, der begynder klokken otte, bliver det
+	// tidligt på dagen — hvad det præcist runder til, er ikke det, der prøves her.
+	await expect(page.locator(`[data-date="${to}"] .tevent`).getByText('skifte dæk')).toBeVisible();
+	await expect(page.locator(`[data-date="${from}"]`).getByText('skifte dæk')).toBeHidden();
 	await expect(page.locator(`[data-allday="${from}"]`).getByText('skifte dæk')).toBeHidden();

 	expect(trouble).toEqual([]);
@@ -1178,9 +1178,8 @@ test('kalenderen viser Googles begivenheder over egne opgaver, og kun opgaven ka
 	// få prøven til at bestå: det er også sådan et menneske gør det, fordi man
 	// slipper der, hvor man kan se, man slipper.
 	await task.dragTo(page.locator(`[data-date="${next}"]`), { targetPosition: { x: 30, y: 20 } });
-	// Landet i næste dags bånd: et træk hen på en dag flytter datoen og sætter ikke
-	// et klokkeslæt, så opgaven har ingen tid at stå ved.
-	await expect(page.locator(`[data-allday="${next}"]`).getByText('vande blomster')).toBeVisible();
+	// Landet i næste dags timesøjle, med det klokkeslæt der blev sluppet på.
+	await expect(page.locator(`[data-date="${next}"] .tevent`).getByText('vande blomster')).toBeVisible();
 	await expect(band.getByText('vande blomster')).toBeHidden();
 	// The events stayed where they were; a rescheduled task moves nothing else.
 	await expect(cell.locator('.tevent')).toHaveCount(1);
@@ -3210,3 +3209,97 @@ test('ugen viser et døgn, og dagene er lige brede', async ({ page }) => {

 	expect(trouble).toEqual([]);
 });
+
+/**
+ * Tid på en opgave, sat i ruden og justeret i kalenderen.
+ *
+ * Tre påstande, og den midterste er den, der var gået galt uden at nogen sagde
+ * det: serveren læser `due_date` og `due_time` sammen, så en dato sendt uden en
+ * tid *rydder* tiden. Et gem af datoen alene tog altså klokkeslættet med sig, og
+ * det samme gjorde et træk i kalenderen.
+ */
+test('en opgave kan få et klokkeslæt, og beholder det når den flyttes', async ({ page }) => {
+	const trouble = watchForTrouble(page);
+	await page.goto('/');
+
+	const box = page.getByLabel('Ny opgave');
+	// I dag, så den står på den visning, den skrives i — og i den uge, gitteret
+	// åbner på længere nede.
+	await box.fill('ringe til tandlægen i dag');
+	await box.press('Enter');
+	await expect(page.getByText('ringe til tandlægen')).toBeVisible();
+
+	// Klokkeslættet sættes i ruden. Feltet er tomt til at begynde med: en opgave
+	// uden tid er det almindelige, og 00:00 ville påstå noget om midnat.
+	await page.getByText('ringe til tandlægen').click();
+	const time = page.getByLabel('Klokkeslæt');
+	await expect(time).toHaveValue('');
+	// Tidligt på dagen med vilje: gitteret begynder klokken otte, så opgaven står
+	// lige under båndet og de to kasser er i billedet på én gang. Klokken fjorten
+	// ligger under skærmkanten, og et træk, der først skal rulle, er et træk,
+	// browseren taber.
+	await time.fill('08:30');
+	await time.blur();
+	await page.waitForTimeout(400);
+
+	// Gemt hos serveren, ikke kun i feltet: genindlæst og åbnet igen.
+	await page.reload();
+	await page.getByText('ringe til tandlægen').click();
+	await expect(page.getByLabel('Klokkeslæt'), 'klokkeslættet blev ikke gemt').toHaveValue('08:30');
+
+	// Og datoen kan rettes bagefter uden at tage timen med sig.
+	const date = page.locator('#due');
+	const day = await date.inputValue();
+	await date.fill(day);
+	await date.blur();
+	await page.waitForTimeout(400);
+	await page.reload();
+	await page.getByText('ringe til tandlægen').click();
+	await expect(
+		page.getByLabel('Klokkeslæt'),
+		'et gem af datoen ryddede klokkeslættet'
+	).toHaveValue('08:30');
+
+	await page.keyboard.press('Escape');
+
+	// I ugegitteret står den på sit klokkeslæt frem for i heldagsbåndet.
+	await page.goto('/upcoming');
+	await page.getByRole('button', { name: 'Uge', exact: true }).click();
+	const placed = page.locator('.tevent.task').filter({ hasText: 'ringe til tandlægen' });
+	await expect(placed, 'opgaven står ikke på døgnet').toBeVisible();
+	await expect(placed).toContainText('08:30');
+
+	// Trukket op i båndet over sin egen dag: så har den en dag og ingen tid. Den
+	// tomme streng siger "ryd", hvor ingenting siger "behold" — og de to må ikke
+	// forveksles.
+	//
+	// Et bånd, der er tomt. Prøven handler om at krydse mellem de to kasser, og en
+	// dag, hvis bånd allerede er fyldt af andre prøvers opgaver, gør slippunktet
+	// til en anden opgave frem for til båndet — hvilket er en anden gest end den,
+	// der prøves her.
+	const band = page
+		.locator('.weekgrid > .allday')
+		.filter({ hasNot: page.locator('.chip, .event') })
+		.first();
+	const today = await band.getAttribute('data-allday');
+	// Trukket i skridt frem for i ét spring. `dragTo` flytter musen i to træk, og
+	// over fire hundrede pixels i et travlt gitter giver det browseren for få
+	// mellemstationer til at holde gesten i live. Et menneske bevæger hånden hele
+	// vejen, og det er også det, der skal prøves.
+	const fromBox = await placed.boundingBox();
+	const toBox = await band.boundingBox();
+	await page.mouse.move(fromBox.x + fromBox.width / 2, fromBox.y + 5);
+	await page.mouse.down();
+	await page.mouse.move(toBox.x + toBox.width / 2, toBox.y + toBox.height / 2, { steps: 25 });
+	await page.mouse.up();
+	await expect(
+		page.locator(`[data-allday="${today}"] .chip`).filter({ hasText: 'ringe til tandlægen' }),
+		'opgaven kom ikke op i båndet'
+	).toBeVisible();
+	await expect(
+		page.locator(`[data-date="${today}"] .tevent`).filter({ hasText: 'ringe til tandlægen' }),
+		'opgaven står stadig på et klokkeslæt'
+	).toBeHidden();
+
+	expect(trouble).toEqual([]);
+});
@@ -366,6 +366,8 @@ export const api = {
 	pushKey: () => get('/push/key'),
 	subscribePush: (subscription) => post('/push/subscribe', subscription),
 	unsubscribePush: (endpoint) => post('/push/unsubscribe', { endpoint, keys: {} }),
+	// Teksten kommer herfra, fordi ordbøgerne gør. Serveren har ingen.
+	testPush: (title, body) => post('/push/test', { title, body }),

 	// --- integrations
 	getMailAddress: () => get('/mail-address'),
@@ -272,6 +272,15 @@
 		over = iso(date);
 	}

+	/**
+	 * Sluppet på en dag, uden at sige noget om klokkeslættet — så beholder opgaven
+	 * det, den har. Måneden er den her: en rude er en dag, ikke et døgn, og der er
+	 * ingen tid at læse ud af hvor man slap.
+	 *
+	 * Det var ikke sådan før. Trækket sendte kun datoen, og serveren læser en dato
+	 * uden en tid som "ryd tiden" — så en opgave klokken 14 mistede sit
+	 * klokkeslæt ved at blive flyttet til dagen efter, uden at nogen bad om det.
+	 */
 	async function onDrop(event, date) {
 		event.preventDefault();
 		const id = dragged(event, TASK);
@@ -280,6 +289,44 @@
 		await app.reschedule(id, iso(date));
 	}

+	/**
+	 * Sluppet et sted på døgnet: dér, man slap, er klokkeslættet.
+	 *
+	 * Målt mod søjlens egen kasse frem for mod siden, så det bliver rigtigt, uanset
+	 * hvor gitteret sidder, og uanset hvor langt der er rullet.
+	 *
+	 * Rundet til kvarter. Minuttet under markøren er ikke en oplysning, nogen har —
+	 * pegefingeren er bredere end et minut — og 14:07 er et tal, der ser ud som om
+	 * det blev valgt, hvilket er værre end at være omtrentligt.
+	 */
+	async function onDropAt(event, date) {
+		event.preventDefault();
+		const id = dragged(event, TASK);
+		over = null;
+		if (!id) return;
+
+		const box = event.currentTarget.getBoundingClientRect();
+		const share = Math.min(Math.max((event.clientY - box.top) / box.height, 0), 1);
+		const minutes = hours.from * 60 + share * hours.minutes;
+		const snapped = Math.min(Math.round(minutes / 15) * 15, 24 * 60 - 15);
+		await app.reschedule(id, iso(date), clock(snapped));
+	}
+
+	/**
+	 * Sluppet i båndet foroven: opgaven har en dag og ingen tid.
+	 *
+	 * Den tomme streng er ikke det samme som ingenting her — den siger "ryd", hvor
+	 * `undefined` siger "behold". Det er hele grunden til, at de to er skilt ad i
+	 * `reschedule`.
+	 */
+	async function onDropAllDay(event, date) {
+		event.preventDefault();
+		const id = dragged(event, TASK);
+		over = null;
+		if (!id) return;
+		await app.reschedule(id, iso(date), '');
+	}
+
 	// --- ugen som et døgn ---------------------------------------------------------
 	//
 	// En uge, hvor hver dag er en punktopstilling, svarer på "hvad skal der ske
@@ -525,7 +572,7 @@
 						class:over={over === iso(date)}
 						ondragover={(e) => onDragOver(e, date)}
 						ondragleave={() => (over = null)}
-						ondrop={(e) => onDrop(e, date)}
+						ondrop={(e) => onDropAllDay(e, date)}
 					>
 						{#each untimedOn(date) as item (item.kind + item.ref.id)}
 							{#if item.kind === 'event'}
@@ -556,7 +603,7 @@
 						class:over={over === iso(date)}
 						ondragover={(e) => onDragOver(e, date)}
 						ondragleave={() => (over = null)}
-						ondrop={(e) => onDrop(e, date)}
+						ondrop={(e) => onDropAt(e, date)}
 					>
 						{#each Array(hours.count) as _, i}
 							<div class="hourline" style="top:{(i / hours.count) * 100}%"></div>
@@ -11,7 +11,7 @@
 	 * necessarily the last one sent.
 	 */
 	import { api, humanMessage } from '$lib/api.js';
-	import { app, projectName } from '$lib/stores.svelte.js';
+	import { app, projectName, clockOf } from '$lib/stores.svelte.js';
 	import { focusOnMount } from '$lib/focus.js';
 	import { t } from '$lib/i18n.svelte.js';
 	import { REPEATS } from '$lib/when.js';
@@ -22,6 +22,7 @@
 	let description = $state('');
 	let priority = $state(4);
 	let dueDate = $state('');
+	let dueTime = $state('');
 	let labels = $state('');
 	let projectId = $state('');
 	let recurrence = $state('');
@@ -55,6 +56,7 @@
 		description = task.description ?? '';
 		priority = task.priority;
 		dueDate = task.due_date ?? '';
+		dueTime = task.due_datetime ? clockOf(task.due_datetime) : '';
 		labels = (task.labels ?? []).join(', ');
 		projectId = task.project_id;
 		recurrence = task.recurrence_rule ?? '';
@@ -407,14 +409,34 @@
 				</select>
 			</div>

+			<!--
+				Dato og klokkeslæt gemmes sammen, altid.
+
+				Serveren læser de to felter som ét: kommer datoen uden en tid, *ryddes*
+				tiden. Så et gem af datoen alene tog klokkeslættet med sig — man rettede
+				dagen og mistede timen, uden at noget sagde det.
+
+				Tiden er tom, indtil nogen sætter den. En opgave uden klokkeslæt er det
+				almindelige, og et felt, der åbner på 00:00, er et felt, der påstår, at
+				noget skal ske ved midnat.
+			-->
 			<div class="field">
 				<label for="due">{t('detail.due')}</label>
-				<input
-					id="due"
-					type="date"
-					bind:value={dueDate}
-					onchange={() => save({ due_date: dueDate })}
-				/>
+				<div class="due">
+					<input
+						id="due"
+						type="date"
+						bind:value={dueDate}
+						onchange={() => save({ due_date: dueDate, due_time: dueTime })}
+					/>
+					<input
+						type="time"
+						aria-label={t('detail.dueTime')}
+						bind:value={dueTime}
+						disabled={!dueDate}
+						onchange={() => save({ due_date: dueDate, due_time: dueTime })}
+					/>
+				</div>
 			</div>
 		</div>

@@ -692,6 +714,27 @@
 		padding-bottom: max(var(--s8), env(safe-area-inset-bottom));
 	}

+	/* Dato og tid på én linje: de er ét svar på ét spørgsmål, og tiden er den
+	   smalle halvdel af det. */
+	.due {
+		display: flex;
+		gap: var(--s2);
+	}
+
+	.due input[type='date'] {
+		flex: 1;
+		min-width: 0;
+	}
+
+	.due input[type='time'] {
+		flex: none;
+		width: 7.5rem;
+	}
+
+	.due input:disabled {
+		opacity: 0.5;
+	}
+
 	.field {
 		display: flex;
 		flex-direction: column;
@@ -242,6 +242,13 @@ export const da = {
 	'push.turnOff': 'Slå fra',
 	'push.turnOn': 'Slå til på denne enhed',
 	'push.perBrowser': 'Gælder kun den browser, du sidder i nu.',
+	'push.test': 'Send en prøve',
+	'push.testing': 'Sender …',
+	'push.testTitle': 'Prøve fra verdande',
+	'push.testBody': 'Kom den frem, virker notifikationer på denne enhed.',
+	'push.testSent': 'Sendt til {n} enhed(er). Kom den ikke frem, er det browseren eller styresystemet, der holder den tilbage — se om verdande må sende notifikationer.',
+	'push.testNone': 'Ingen enheder er tilmeldt endnu. Slå notifikationer til her på enheden først.',
+	'push.testFailed': '{service} afviste den: {reason}',
 	'push.recent': 'Seneste',
 	'push.none': 'Ingenting endnu.',
 	'push.open': 'Åbn',
@@ -551,6 +558,7 @@ export const da = {
 	'detail.p1': 'P1 — haster',
 	'detail.none': 'Ingen',
 	'detail.due': 'Forfalder',
+	'detail.dueTime': 'Klokkeslæt',
 	'detail.labels': 'Etiketter',
 	'detail.labelsPlaceholder': 'adskilt af komma',
 	'detail.project': 'Projekt',
@@ -238,6 +238,13 @@ export const en = {
 	'push.turnOff': 'Turn off',
 	'push.turnOn': 'Turn on for this device',
 	'push.perBrowser': 'Applies only to the browser you are in right now.',
+	'push.test': 'Send a test',
+	'push.testing': 'Sending …',
+	'push.testTitle': 'Test from verdande',
+	'push.testBody': 'If this arrived, notifications work on this device.',
+	'push.testSent': 'Sent to {n} device(s). If nothing arrived, the browser or the operating system is holding it back — check that verdande is allowed to send notifications.',
+	'push.testNone': 'No devices are registered yet. Turn notifications on here first.',
+	'push.testFailed': '{service} refused it: {reason}',
 	'push.recent': 'Recent',
 	'push.none': 'Nothing yet.',
 	'push.open': 'Open',
@@ -547,6 +554,7 @@ export const en = {
 	'detail.p1': 'P1 — urgent',
 	'detail.none': 'None',
 	'detail.due': 'Due',
+	'detail.dueTime': 'Time',
 	'detail.labels': 'Labels',
 	'detail.labelsPlaceholder': 'separated by commas',
 	'detail.project': 'Project',
@@ -372,10 +372,35 @@ class AppState {
 	}

 	/** Puts a task on a day — dropping it on one, in Kommende or in a month grid. */
-	async reschedule(id, date) {
+	/**
+	 * Flytter en opgave til en dag — og afgør, hvad der sker med klokkeslættet.
+	 *
+	 * Serveren læser `due_date` og `due_time` sammen: kommer datoen uden en tid,
+	 * *ryddes* tiden. Det er den rigtige regel for et felt, man skriver i, og den
+	 * forkerte for et træk i en kalender — en opgave, der stod klokken 14, mistede
+	 * sit klokkeslæt ved at blive trukket til dagen efter, uden at nogen bad om
+	 * det, og uden at noget sagde det.
+	 *
+	 * Så tiden siges nu højt, tre måder:
+	 *
+	 *   time === undefined  behold den, opgaven har
+	 *   time === ''         ryd den — det er heldagsbåndet
+	 *   time === 'HH:MM'    sæt den — det er et sted på døgnet
+	 *
+	 * `undefined` og `''` er med vilje to forskellige ting her. De ligner hinanden
+	 * i JavaScript, og det er præcis derfor de skal skilles ad ét sted frem for at
+	 * blive forvekslet fire steder.
+	 */
+	async reschedule(id, date, time) {
 		const previous = this.get(id);
-		if (!previous || previous.due_date === date) return;
-		await this.update(id, { due_date: date });
+		if (!previous) return;
+
+		const clock =
+			time === undefined ? (previous.due_datetime ? clockOf(previous.due_datetime) : '') : time;
+		if (previous.due_date === date && (previous.due_datetime ? clockOf(previous.due_datetime) : '') === clock) {
+			return;
+		}
+		await this.update(id, { due_date: date, due_time: clock });
 	}

 	async remove(id) {
@@ -729,6 +754,20 @@ class AppState {
 * Only while it still carries a name the server gave it. Rename it and that is your
 * name for it, in every language — the same rule as any other project.
 */
+/**
+ * Klokkeslættet på en opgave, som "HH:MM" i den maskine, der ser på det.
+ *
+ * `Date` og ikke en strengudskæring: `due_datetime` kommer som UTC med et Z på,
+ * og de fjorten på et stempel er ikke klokken fjorten for den, der læser det.
+ * TaskRow viser tiden på nøjagtig samme måde, og de to steder skal vise det
+ * samme tal.
+ */
+export function clockOf(stamp) {
+	const at = new Date(stamp);
+	if (Number.isNaN(at.getTime())) return '';
+	return `${String(at.getHours()).padStart(2, '0')}:${String(at.getMinutes()).padStart(2, '0')}`;
+}
+
 const SYSTEM_INBOX_NAMES = new Set(['indbakke', 'inbox']);

 export function projectName(project) {
@@ -35,6 +35,43 @@
 		}
 	}

+	let testing = $state(false);
+	let testResult = $state(null);
+
+	/**
+	 * Én notifikation, hele vejen gennem den rigtige rute, og et svar på hvad der
+	 * skete med den.
+	 *
+	 * Den siger ikke "sendt" og lader det være. Kommer den frem, ved man det, fordi
+	 * den ligger på skærmen; kommer den ikke, står der her, hvem der afviste den og
+	 * med hvilke ord — og hvis ingen afviste den, står der, at det så er browseren
+	 * eller styresystemet, der holder den tilbage. Det er de tre steder, den kan
+	 * blive væk, og nu peger svaret på ét af dem.
+	 */
+	async function testPush() {
+		testing = true;
+		testResult = null;
+		try {
+			const r = await api.testPush(t('push.testTitle'), t('push.testBody'));
+			if (!r.subscriptions) {
+				testResult = { bad: true, text: t('push.testNone') };
+			} else if (r.failed?.length) {
+				testResult = {
+					bad: true,
+					text: r.failed
+						.map((f) => t('push.testFailed', { service: f.service, reason: f.reason }))
+						.join(' ')
+				};
+			} else {
+				testResult = { bad: false, text: t('push.testSent', { n: r.sent }) };
+			}
+		} catch (e) {
+			testResult = { bad: true, text: humanMessage(e) };
+		} finally {
+			testing = false;
+		}
+	}
+
 	async function disablePush() {
 		busy = true;
 		try {
@@ -165,7 +202,18 @@
 		<p class="hint">{t('push.on')}</p>
 		<div class="row">
 			<button class="secondary" onclick={disablePush} disabled={busy}>{t('push.turnOff')}</button>
+			<!-- "Til" er ikke det samme som "virker".
+			     Ruden sagde til, så snart der var et abonnement, og en push, tjenesten
+			     afviste, gik i en logline på Debug, som ingen ser. Tre forskellige
+			     problemer — browseren tilmeldte sig aldrig, tjenesten afviste den,
+			     der er ikke noget forfaldent endnu — så ens ud fra den her side. -->
+			<button class="secondary" onclick={testPush} disabled={busy || testing}>
+				{testing ? t('push.testing') : t('push.test')}
+			</button>
 		</div>
+		{#if testResult}
+			<p class="hint" class:bad={testResult.bad}>{testResult.text}</p>
+		{/if}
 	{:else}
 		<div class="row">
 			<button class="primary" onclick={enablePush} disabled={busy}>
@@ -261,6 +309,10 @@
 {/if}

 <style>
+	.bad {
+		color: var(--danger);
+	}
+
 	.what {
 		display: flex;
 		flex-direction: column;