Rewrite AGENTS.md sentence by sentence

Rewrite the agent rules from scratch, with one idea per sentence and
every file name and command in backticks. Drop the rule that models
embed `models.Base`, which no package has. Say that the linter keeps
tests in external test packages, and that an `export_test.go` file
gives them access to unexported code. Limit the rules on doc comments
and blank imports to files outside the tests. State magic numbers as
a preference, and correct the blank-line rule for `return`. State the
branch workflow: pull requests target `next` and only the owner
merges `next` into `main`. Record the three snake_case JSON tags the
HTTP API keeps.

Part of #190.

Model: fable-5-1 (writing); opus-5-5 (rework)

.golangci.yml

@@ -61,6 +61,10 @@ linters:
               desc: >-
                 Test-support code belongs in test files and in packages whose
                 directory name ends in test, not in the shipped binary.
+            - pkg: sneak.berlin/go/neoirc/internal/dbtest
+              desc: >-
+                Test-support code belongs in test files and in packages whose
+                directory name ends in test, not in the shipped binary.
     # Only decisions already recorded in the Go package defaults are
     # listed here. Every entry matches the module path exactly.
     gomodguard_v2:

AGENTS.md

@@ -1,55 +1,73 @@
-# AGENTS.md — Rules for AI Agents
+# Rules for coding agents
 
-## Before Every Commit
+This file holds the rules for coding agents working in this repository.
+`CONVENTIONS.md` defines the architecture. `REPO_POLICIES.md` defines the
+repository standards. Both are copies of shared documents. Do not edit them
+here.
 
-1. **Format**: `make fmt`
-2. **Check**: `make check` — the tests and the linter, which run in Docker, and
-   the format check: all passing, zero issues
+## Before every commit
 
-Never run `go test`, `golangci-lint` or `gofmt` directly; use the `make`
-targets.
+1. Run `make fmt`.
+2. Run `make check`. It runs the tests and the linter in Docker, then the format
+   check. All three must pass with no findings.
 
-No commit lands on main with lint errors, test failures, or formatting issues.
+Never run `go test`, `golangci-lint` or `gofmt` directly. Use the `make` targets
+instead, such as `make test` and `make lint`.
 
-## Code Style
+## Branches and pull requests
 
-- Follow CONVENTIONS.md exactly — it defines the architecture
-- All exported types, functions, methods, and vars must have doc comments
-- All packages must have a package doc comment
-- JSON tags use camelCase (not snake_case)
-- No magic numbers — use named constants
-- No inline error handling (`if err := ...; err != nil`) — use plain assignment
-- Blank line before every `return` statement
-- Blank line separating embedded fields from regular fields in structs
-- Blank imports must have a justification comment
+- Never commit to `main` or `next` directly. Every change is a pull request from
+  a feature branch into `next`.
+- Only the owner merges `next` into `main`.
+- A pull request that closes an issue has the title `Description (closes #N)`.
+- One logical change per commit.
+- Commit messages are in the imperative mood and short.
 
-## Git Workflow
+## Code style
 
-- **Never commit directly to main** — all changes go on feature branches
-- Merge to main only when ready and passing all checks
-- PR titles: `Description (closes #N)` when closing an issue
-- One logical change per commit
-- Commit messages: imperative mood, concise
+- Follow `CONVENTIONS.md`.
+- Outside test files, every package has a package doc comment.
+- Outside test files, every exported type, function and variable has a doc
+  comment.
+- JSON tags are camelCase. The HTTP API's `last_id`, `pow_token` and
+  `hashcash_bits` stay as they are, each with a `//nolint:tagliatelle` comment.
+- Prefer named constants to magic numbers. The `mnd` linter checks for them
+  outside test files.
+- No inline error handling such as `if err := f(); err != nil`. Assign the error
+  on its own line, then test it.
+- A `return` that follows another statement in its block has a blank line before
+  it.
+- A blank line between the embedded fields of a struct and its other fields.
+- Outside test files, every blank import has a comment saying why it is there.
 
 ## Architecture
 
-- Dependency injection via Uber fx — all components are fx providers
-- `internal/` for all application packages — one package per concern
-- Handlers return `http.HandlerFunc` using the closure pattern
-- Request/response structs defined inside handler closures
-- Models embed `models.Base` for database access to relation methods
-- Database migrations in `internal/db/schema/` — embedded via `go:embed`
-- SQLite by default (pure Go driver: modernc.org/sqlite)
+- The server uses `go.uber.org/fx` for dependency injection.
+  `cmd/neoircd/main.go` lists its `fx` providers, such as `db.New` and
+  `handlers.New`.
+- Application packages live under `internal/`, one package per concern.
+- `pkg/irc` holds the IRC command names and numeric reply codes.
+- The `web` package embeds the built web client.
+- Each exported `Handle…` method of `Handlers` returns an `http.HandlerFunc`.
+- A request struct is defined inside the method that decodes it.
+- The server uses the database only through the methods of `db.Database`.
+- The database migrations live in `internal/db/schema/` and are embedded with
+  `go:embed`.
+- The database is SQLite, through the pure Go driver `modernc.org/sqlite`.
 
 ## Testing
 
-- Table-driven tests preferred
-- Use `testing.T` helpers, not assertion libraries
-- Test files live next to the code they test
-- `_test.go` suffix, same package for white-box testing
+- Prefer table-driven tests.
+- Use `testing.T` helpers, not assertion libraries.
+- A test file lives next to the code it tests and ends in `_test.go`.
+- The linter requires each test file to be in the package's external test
+  package, such as `handlers_test`. It allows `export_test.go` and files ending
+  in `_internal_test.go` in the package itself.
+- An `export_test.go` file gives the external tests access to the package's
+  unexported code.
 
 ## Dependencies
 
-- Required libraries are listed in CONVENTIONS.md §1
-- No new dependencies without justification
-- Pure Go preferred (no CGO)
+- The required libraries are listed in `CONVENTIONS.md` §1.
+- No new dependency without a reason given in the pull request.
+- Prefer dependencies written in pure Go, which build without cgo.

README.md

@@ -2611,7 +2611,7 @@ listener.
 | Variable               | Type   | Default                                                                                | Description                                                                                                                                                                                                                                                                             |
 | ---------------------- | ------ | -------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `PORT`                 | int    | `8080`                                                                                 | HTTP listen port                                                                                                                                                                                                                                                                        |
-| `DBURL`                | string | `file:///var/lib/neoirc/state.db?_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)` | SQLite connection string. For file-based: `file:///path/to/db.db?_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)`. For in-memory (testing): `file::memory:?cache=shared`. See [SQLite Considerations](#sqlite-considerations).                                                     |
+| `DBURL`                | string | `file:///var/lib/neoirc/state.db?_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)` | SQLite connection string. For file-based: `file:///path/to/db.db?_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)`. For in-memory (testing): `file::memory:?cache=shared`. It must not set `foreign_keys`. See [SQLite Considerations](#sqlite-considerations).                     |
 | `DEBUG`                | bool   | `false`                                                                                | Switch logging to debug level                                                                                                                                                                                                                                                           |
 | `MESSAGE_MAX_AGE`      | string | `720h`                                                                                 | Maximum age of messages as a Go duration string (e.g. `720h`, `24h`). Messages older than this are pruned. Default is 30 days.                                                                                                                                                          |
 | `SESSION_IDLE_TIMEOUT` | string | `720h`                                                                                 | Idle timeout as a Go duration string (e.g. `720h`, `24h`). Clients with no authenticated HTTP API request or IRC listener command for this long are removed, and a session left with none is expired and its nick released (see [Data Lifecycle](#data-lifecycle)). Default is 30 days. |
@@ -3342,6 +3342,7 @@ neoirc/
 │   │   └── schema/
 │   │       ├── 000.sql     # schema_migrations bootstrap
 │   │       └── 001_initial.sql
+│   ├── dbtest/             # Gives each test its own database; only tests import it
 │   ├── globals/            # Application-wide metadata
 │   │   └── globals.go
 │   ├── handlers/           # HTTP request handlers

internal/cli/api/client.go

@@ -25,7 +25,10 @@ const (
 	httpErrThreshold = 400
 )
 
-var errHTTP = errors.New("HTTP error")
+var (
+	errHTTP        = errors.New("HTTP error")
+	errJoinRefused = errors.New("the server refused the join")
+)
 
 // Client wraps HTTP calls to the neoirc server API.
 type Client struct {
@@ -206,13 +209,35 @@ func (client *Client) PollMessages(
 	}, nil
 }
 
-// JoinChannel joins a channel.
+// JoinChannel joins a channel. It returns an error unless the
+// server answers that the session joined. When the server
+// refuses the join, it sends the reason to the message queue as
+// an error numeric.
 func (client *Client) JoinChannel(channel string) error {
-	return client.SendMessage(
+	data, err := client.do(
+		http.MethodPost, "/api/v1/messages",
 		&Message{ //nolint:exhaustruct // only command+to needed
 			Command: irc.CmdJoin, To: channel,
 		},
 	)
+	if err != nil {
+		return err
+	}
+
+	var resp struct {
+		Status string `json:"status"`
+	}
+
+	err = json.Unmarshal(data, &resp)
+	if err != nil {
+		return fmt.Errorf("decode join: %w", err)
+	}
+
+	if resp.Status != "joined" {
+		return errJoinRefused
+	}
+
+	return nil
 }
 
 // PartChannel leaves a channel.

internal/cli/app.go

@@ -96,20 +96,7 @@ func (a *App) handleInput(text string) {
 		a.ui.AddStatus(
 			"[red]Send error: " + err.Error(),
 		)
-
-		return
 	}
-
-	timestamp := time.Now().Format(timeFormat)
-
-	a.mu.Lock()
-	nick := a.nick
-	a.mu.Unlock()
-
-	a.ui.AddLine(target, fmt.Sprintf(
-		"[gray]%s [green]<%s>[white] %s",
-		timestamp, nick, text,
-	))
 }
 
 func (a *App) handleCommand(text string) {
@@ -301,9 +288,6 @@ func (a *App) cmdJoin(channel string) {
 	a.mu.Unlock()
 
 	a.ui.SwitchToBuffer(channel)
-	a.ui.AddLine(channel,
-		"[yellow]*** Joined "+channel,
-	)
 	a.ui.SetStatus(nick, channel, "connected")
 }
 
@@ -338,10 +322,6 @@ func (a *App) cmdPart(channel string) {
 		return
 	}
 
-	a.ui.AddLine(channel,
-		"[yellow]*** Left "+channel,
-	)
-
 	a.mu.Lock()
 	if a.target == channel {
 		a.target = ""
@@ -368,7 +348,6 @@ func (a *App) cmdMsg(args string) {
 
 	a.mu.Lock()
 	connected := a.connected
-	nick := a.nick
 	a.mu.Unlock()
 
 	if !connected {
@@ -386,16 +365,7 @@ func (a *App) cmdMsg(args string) {
 		a.ui.AddStatus(fmt.Sprintf(
 			"[red]Send failed: %v", err,
 		))
-
-		return
 	}
-
-	timestamp := time.Now().Format(timeFormat)
-
-	a.ui.AddLine(target, fmt.Sprintf(
-		"[gray]%s [green]<%s>[white] %s",
-		timestamp, nick, text,
-	))
 }
 
 func (a *App) cmdQuery(nick string) {
@@ -785,12 +755,10 @@ func (a *App) handlePrivmsgEvent(
 	lines := msg.BodyLines()
 	text := strings.Join(lines, " ")
 
-	if msg.From == myNick {
-		return
-	}
-
+	// A direct message shows in the buffer of the other user:
+	// the recipient of one the user sent, else the sender.
 	target := msg.To
-	if !strings.HasPrefix(target, "#") {
+	if !strings.HasPrefix(target, "#") && msg.From != myNick {
 		target = msg.From
 	}
 
@@ -813,31 +781,35 @@ func (a *App) handleJoinEvent(
 	))
 }
 
-// handlePartEvent shows another user's part. The server
-// also sends the user's own part back to it, which cmdPart
-// has already shown; showing it again would add a second
-// line and mark the channel just left as unread.
+// handlePartEvent shows a part in the channel's buffer. The
+// user's own part does not mark the channel unread: the user
+// has just left it.
 func (a *App) handlePartEvent(
 	msg *api.Message, timestamp, myNick string,
 ) {
-	if msg.To == "" || msg.From == myNick {
+	if msg.To == "" {
 		return
 	}
 
 	lines := msg.BodyLines()
 	reason := strings.Join(lines, " ")
 
+	line := fmt.Sprintf(
+		"[gray]%s [yellow]*** %s has left %s",
+		timestamp, msg.From, msg.To,
+	)
+
 	if reason != "" {
-		a.ui.AddLine(msg.To, fmt.Sprintf(
-			"[gray]%s [yellow]*** %s has left %s (%s)",
-			timestamp, msg.From, msg.To, reason,
-		))
-	} else {
-		a.ui.AddLine(msg.To, fmt.Sprintf(
-			"[gray]%s [yellow]*** %s has left %s",
-			timestamp, msg.From, msg.To,
-		))
+		line += " (" + reason + ")"
 	}
+
+	if msg.From == myNick {
+		a.ui.AddLineAsRead(msg.To, line)
+
+		return
+	}
+
+	a.ui.AddLine(msg.To, line)
 }
 
 func (a *App) handleQuitEvent(

internal/cli/app_internal_test.go

@@ -1,6 +1,9 @@
 package cli
 
 import (
+	"io"
+	"net/http"
+	"net/http/httptest"
 	"testing"
 
 	"github.com/gdamore/tcell/v2"
@@ -8,6 +11,15 @@ import (
 	"sneak.berlin/go/neoirc/pkg/irc"
 )
 
+// The user's nick, a channel it is in, another user's nick and
+// a message text, for the tests below.
+const (
+	testNick      = "erin"
+	testChannel   = "#chan"
+	testOtherNick = "bob"
+	testText      = "hello"
+)
+
 func TestMemberPrefix(t *testing.T) {
 	t.Parallel()
 
@@ -53,48 +65,257 @@ func TestMemberPrefix(t *testing.T) {
 }
 
 // TestPartEvent checks that a PART event adds a line to the
-// channel's buffer and marks it unread, except for the
-// user's own part, which cmdPart has already shown.
+// channel's buffer and marks it unread, except that the
+// user's own part does not mark it unread.
 func TestPartEvent(t *testing.T) {
 	t.Parallel()
 
 	tests := []struct {
 		name       string
 		from       string
-		wantLines  int
 		wantUnread int
 	}{
-		{name: "own part", from: "erin", wantLines: 0, wantUnread: 0},
-		{name: "other member", from: "bob", wantLines: 1, wantUnread: 1},
+		{name: "own part", from: testNick, wantUnread: 0},
+		{name: "other member", from: testOtherNick, wantUnread: 1},
 	}
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
 			t.Parallel()
 
-			app := &App{ui: NewUI(), nick: "erin"}
+			app := &App{ui: NewUI(), nick: testNick}
 			runUI(t, app.ui)
 
 			app.handleServerMessage(&api.Message{
-				Command: irc.CmdPart, From: test.from, To: "#chan",
+				Command: irc.CmdPart, From: test.from, To: testChannel,
 			})
 
-			var lines, unread int
-
-			app.ui.app.QueueUpdate(func() {
-				buf := app.ui.getOrCreateBuffer("#chan")
-				lines = len(buf.Lines)
-				unread = buf.Unread
-			})
-
-			if lines != test.wantLines || unread != test.wantUnread {
-				t.Fatalf("got %d lines and %d unread, want %d and %d",
-					lines, unread, test.wantLines, test.wantUnread)
+			lines, unread := bufferState(app.ui, testChannel)
+			if lines != 1 || unread != test.wantUnread {
+				t.Fatalf("got %d lines and %d unread, want 1 and %d",
+					lines, unread, test.wantUnread)
 			}
 		})
 	}
 }
 
+// TestOwnCommandShownOnce checks that a message, join or
+// part made from neoirc-cli shows as one line in the
+// channel's buffer once the server's event for it arrives,
+// and does not mark the channel unread.
+func TestOwnCommandShownOnce(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name  string
+		send  func(app *App)
+		event api.Message
+	}{
+		{
+			name: "message",
+			send: func(app *App) { app.handleInput(testText) },
+			event: api.Message{
+				Command: irc.CmdPrivmsg, From: testNick, To: testChannel,
+				Body: []string{testText},
+			},
+		},
+		{
+			name: "join",
+			send: func(app *App) { app.cmdJoin(testChannel) },
+			event: api.Message{
+				Command: irc.CmdJoin, From: testNick, To: testChannel,
+			},
+		},
+		{
+			name: "part",
+			send: func(app *App) { app.cmdPart(testChannel) },
+			event: api.Message{
+				Command: irc.CmdPart, From: testNick, To: testChannel,
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			// The server accepts every command. Only the response
+			// to a JOIN is read, and it says the session joined.
+			server := newServer(t, `{"status": "joined"}`)
+
+			app := &App{
+				ui:        NewUI(),
+				client:    api.NewClient(server.URL),
+				nick:      testNick,
+				target:    testChannel,
+				connected: true,
+			}
+			runUI(t, app.ui)
+			app.ui.SwitchToBuffer(testChannel)
+
+			test.send(app)
+			app.handleServerMessage(&test.event)
+
+			lines, unread := bufferState(app.ui, testChannel)
+			if lines != 1 || unread != 0 {
+				t.Fatalf("got %d lines and %d unread, want 1 and 0",
+					lines, unread)
+			}
+		})
+	}
+}
+
+// TestJoinResponse checks that /join switches to the channel's
+// buffer and makes it the target only when the server answers
+// that the session joined.
+func TestJoinResponse(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		response string
+		// The buffer shown and the target after the join.
+		want string
+	}{
+		{
+			name:     "joined",
+			response: `{"status": "joined", "channel": "#chan"}`,
+			want:     testChannel,
+		},
+		{
+			name:     "refused",
+			response: `{"status": "error"}`,
+			want:     testOtherNick,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			app := &App{
+				ui:        NewUI(),
+				client:    api.NewClient(newServer(t, test.response).URL),
+				nick:      testNick,
+				target:    testOtherNick,
+				connected: true,
+			}
+			runUI(t, app.ui)
+			app.ui.SwitchToBuffer(testOtherNick)
+
+			app.cmdJoin(testChannel)
+
+			var shown string
+
+			app.ui.app.QueueUpdate(func() {
+				shown = app.ui.buffers[app.ui.currentBuffer].Name
+			})
+
+			if shown != test.want || app.target != test.want {
+				t.Fatalf("got buffer %s and target %s, want %s",
+					shown, app.target, test.want)
+			}
+		})
+	}
+}
+
+// TestOwnEventFromOtherClient checks that a message, notice,
+// join or part that the user's session makes from another
+// client shows as one line in the buffer it belongs to.
+func TestOwnEventFromOtherClient(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name   string
+		event  api.Message
+		buffer string
+	}{
+		{
+			name: "channel message",
+			event: api.Message{
+				Command: irc.CmdPrivmsg, From: testNick, To: testChannel,
+				Body: []string{testText},
+			},
+			buffer: testChannel,
+		},
+		{
+			name: "direct message",
+			event: api.Message{
+				Command: irc.CmdPrivmsg, From: testNick, To: testOtherNick,
+				Body: []string{testText},
+			},
+			buffer: testOtherNick,
+		},
+		{
+			name: "notice",
+			event: api.Message{
+				Command: irc.CmdNotice, From: testNick, To: testChannel,
+				Body: []string{testText},
+			},
+			buffer: "(status)",
+		},
+		{
+			name: "join",
+			event: api.Message{
+				Command: irc.CmdJoin, From: testNick, To: testChannel,
+			},
+			buffer: testChannel,
+		},
+		{
+			name: "part",
+			event: api.Message{
+				Command: irc.CmdPart, From: testNick, To: testChannel,
+			},
+			buffer: testChannel,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			app := &App{ui: NewUI(), nick: testNick}
+			runUI(t, app.ui)
+
+			app.handleServerMessage(&test.event)
+
+			lines, _ := bufferState(app.ui, test.buffer)
+			if lines != 1 {
+				t.Fatalf("got %d lines in %s, want 1", lines, test.buffer)
+			}
+		})
+	}
+}
+
+// bufferState returns the number of lines in the named
+// buffer and how many of them are unread.
+func bufferState(ui *UI, name string) (int, int) {
+	var lines, unread int
+
+	ui.app.QueueUpdate(func() {
+		buf := ui.getOrCreateBuffer(name)
+		lines = len(buf.Lines)
+		unread = buf.Unread
+	})
+
+	return lines, unread
+}
+
+// newServer starts a server that answers every request with
+// body until the test ends.
+func newServer(t *testing.T, body string) *httptest.Server {
+	t.Helper()
+
+	server := httptest.NewServer(http.HandlerFunc(
+		func(writer http.ResponseWriter, _ *http.Request) {
+			_, _ = io.WriteString(writer, body)
+		},
+	))
+	t.Cleanup(server.Close)
+
+	return server
+}
+
 // runUI runs ui on a simulated screen until the test ends.
 func runUI(t *testing.T, ui *UI) {
 	t.Helper()

internal/cli/ui.go

@@ -95,6 +95,19 @@ func (ui *UI) AddLine(bufferName, line string) {
 	})
 }
 
+// AddLineAsRead adds a line to the specified buffer, as
+// AddLine does, but does not mark the buffer unread.
+func (ui *UI) AddLineAsRead(bufferName, line string) {
+	ui.app.QueueUpdateDraw(func() {
+		buf := ui.getOrCreateBuffer(bufferName)
+		buf.Lines = append(buf.Lines, line)
+
+		if ui.buffers[ui.currentBuffer] == buf {
+			_, _ = fmt.Fprintln(ui.messages, line)
+		}
+	})
+}
+
 // AddStatus adds a line to the status buffer.
 func (ui *UI) AddStatus(line string) {
 	ts := time.Now().Format("15:04")

internal/db/db.go

@@ -5,9 +5,11 @@ import (
 	"context"
 	"database/sql"
 	"embed"
+	"errors"
 	"fmt"
 	"io/fs"
 	"log/slog"
+	"net/url"
 	"sort"
 	"strconv"
 	"strings"
@@ -22,6 +24,10 @@ import (
 
 const minMigrationParts = 2
 
+var errForeignKeysInDBURL = errors.New(
+	"DBURL must not set foreign_keys, which the server always turns on",
+)
+
 // SchemaFiles contains embedded SQL migration files.
 //
 //go:embed schema/*.sql
@@ -90,6 +96,33 @@ func (database *Database) connect(ctx context.Context) error {
 		dbURL = config.DefaultDBURL
 	}
 
+	// SQLite keeps the foreign keys setting per connection. The driver
+	// runs each _pragma parameter on every connection it opens. So the
+	// one added below also covers the connection the pool opens after
+	// a cancelled query breaks the old one. A foreign_keys pragma in
+	// DBURL could undo it, because the driver sorts the pragmas.
+	_, query, hasQuery := strings.Cut(dbURL, "?")
+
+	urlParams, err := url.ParseQuery(query)
+	if err != nil {
+		return fmt.Errorf("parse DBURL: %w", err)
+	}
+
+	for _, pragma := range urlParams["_pragma"] {
+		if strings.Contains(strings.ToLower(pragma), "foreign_keys") {
+			return fmt.Errorf(
+				"%w: _pragma=%s", errForeignKeysInDBURL, pragma,
+			)
+		}
+	}
+
+	separator := "?"
+	if hasQuery {
+		separator = "&"
+	}
+
+	dbURL += separator + "_pragma=foreign_keys(1)"
+
 	database.log.Info(
 		"connecting to database", "url", dbURL,
 	)
@@ -109,13 +142,6 @@ func (database *Database) connect(ctx context.Context) error {
 	database.conn = conn
 	database.log.Info("database connected")
 
-	_, err = database.conn.ExecContext(
-		ctx, "PRAGMA foreign_keys = ON",
-	)
-	if err != nil {
-		return fmt.Errorf("enable foreign keys: %w", err)
-	}
-
 	return database.runMigrations(ctx)
 }
 

internal/db/db_test.go

@@ -1,19 +1,34 @@
 package db_test
 
 import (
+	"context"
+	"errors"
+	"net/url"
 	"path/filepath"
 	"strings"
 	"testing"
+	"time"
 
 	"go.uber.org/fx/fxtest"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/dbtest"
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/logger"
 )
 
 const wantBusyTimeoutMS = 5000
 
+const (
+	// endlessQuery counts the rows of a recursive query that never
+	// stops, so it runs until its context ends.
+	endlessQuery = `WITH RECURSIVE n(x) AS
+		(SELECT 1 UNION ALL SELECT x + 1 FROM n)
+		SELECT COUNT(*) FROM n`
+
+	endlessQueryTimeout = 100 * time.Millisecond
+)
+
 // TestDefaultDBURLSetsWALAndBusyTimeout opens a file database
 // with the default URL's parameters the way the server does,
 // and checks the journal mode and busy timeout it ends up with.
@@ -73,3 +88,191 @@ func TestDefaultDBURLSetsWALAndBusyTimeout(t *testing.T) {
 		)
 	}
 }
+
+// TestForeignKeysOnAfterCancelledQuery cancels a query while it
+// runs, which makes the pool close its only connection and open a
+// new one. A TEMP table lasts only as long as its connection, so
+// its absence shows the connection was replaced. The test then
+// checks that the file database keeps its tables and that the new
+// connection has foreign keys on.
+func TestForeignKeysOnAfterCancelledQuery(t *testing.T) {
+	t.Parallel()
+
+	_, defaultParams, _ := strings.Cut(config.DefaultDBURL, "?")
+
+	urlParams := map[string]string{
+		"default parameters": "?" + defaultParams,
+		"no parameters":      "",
+	}
+
+	for name, params := range urlParams {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			dbURL := "file://" +
+				filepath.Join(t.TempDir(), "state.db") + params
+
+			database, err := startDatabase(t, dbURL)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			_, err = database.GetDB().ExecContext(
+				t.Context(), "CREATE TEMP TABLE first_connection (x)",
+			)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			ctx, cancel := context.WithTimeout(
+				t.Context(), endlessQueryTimeout,
+			)
+			defer cancel()
+
+			_, err = database.GetDB().ExecContext(ctx, endlessQuery)
+			if !errors.Is(err, context.DeadlineExceeded) {
+				t.Fatalf("endless query: err = %v", err)
+			}
+
+			tempTables := queryInt(
+				t, database, "SELECT COUNT(*) FROM sqlite_temp_schema",
+			)
+			if tempTables != 0 {
+				t.Fatal("the pool kept its first connection")
+			}
+
+			migrations := queryInt(
+				t, database, "SELECT COUNT(*) FROM schema_migrations",
+			)
+			if migrations == 0 {
+				t.Error("schema_migrations is empty")
+			}
+
+			foreignKeys := queryInt(t, database, "PRAGMA foreign_keys")
+			if foreignKeys != 1 {
+				t.Errorf("foreign_keys = %d, want 1", foreignKeys)
+			}
+		})
+	}
+}
+
+// TestNewURLKeepsDataAfterCancelledQuery cancels a query on a test
+// database while it runs, which makes the pool close its only
+// connection and open a new one. A TEMP table lasts only as long as
+// its connection, so its absence shows the connection was replaced.
+// The database must still have its tables and rows.
+func TestNewURLKeepsDataAfterCancelledQuery(t *testing.T) {
+	t.Parallel()
+
+	database, err := startDatabase(t, dbtest.NewURL(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = database.GetOrCreateChannel(t.Context(), "#test")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = database.GetDB().ExecContext(
+		t.Context(), "CREATE TEMP TABLE first_connection (x)",
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ctx, cancel := context.WithTimeout(t.Context(), endlessQueryTimeout)
+	defer cancel()
+
+	_, err = database.GetDB().ExecContext(ctx, endlessQuery)
+	if !errors.Is(err, context.DeadlineExceeded) {
+		t.Fatalf("endless query: err = %v", err)
+	}
+
+	tempTables := queryInt(
+		t, database, "SELECT COUNT(*) FROM sqlite_temp_schema",
+	)
+	if tempTables != 0 {
+		t.Fatal("the pool kept its first connection")
+	}
+
+	channels := queryInt(t, database, "SELECT COUNT(*) FROM channels")
+	if channels != 1 {
+		t.Errorf("channels = %d, want 1", channels)
+	}
+}
+
+// TestDBURLSettingForeignKeysFailsStartup checks that the database
+// refuses to start when DBURL sets foreign_keys itself, however it
+// is spelled.
+func TestDBURLSettingForeignKeysFailsStartup(t *testing.T) {
+	t.Parallel()
+
+	pragmas := []string{
+		"foreign_keys(0)",
+		"foreign_keys(off)",
+		"foreign_keys=0",
+		"FOREIGN_KEYS(FALSE)",
+		" Foreign_Keys = 1",
+	}
+
+	for _, pragma := range pragmas {
+		t.Run(pragma, func(t *testing.T) {
+			t.Parallel()
+
+			dbURL := "file://" +
+				filepath.Join(t.TempDir(), "state.db") +
+				"?_pragma=" + url.QueryEscape(pragma)
+
+			_, err := startDatabase(t, dbURL)
+			if err == nil {
+				t.Fatal("the database started")
+			}
+
+			if !strings.Contains(err.Error(), "DBURL") {
+				t.Errorf("error %q does not name DBURL", err)
+			}
+		})
+	}
+}
+
+// startDatabase starts a Database for dbURL the way the server does.
+// It returns the error that stopped it from starting, if any.
+func startDatabase(t *testing.T, dbURL string) (*db.Database, error) {
+	t.Helper()
+
+	lifecycle := fxtest.NewLifecycle(t)
+
+	log, err := logger.New(lifecycle, logger.Params{
+		Globals: &globals.Globals{},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	database, err := db.New(lifecycle, db.Params{
+		Logger: log,
+		Config: &config.Config{DBURL: dbURL},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Cleanup(lifecycle.RequireStop)
+
+	return database, lifecycle.Start(t.Context())
+}
+
+// queryInt runs a query that returns a single number.
+func queryInt(t *testing.T, database *db.Database, query string) int {
+	t.Helper()
+
+	var result int
+
+	err := database.GetDB().QueryRowContext(t.Context(), query).Scan(&result)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return result
+}

internal/db/export_test.go

@@ -5,21 +5,16 @@ import (
 	"database/sql"
 	"fmt"
 	"log/slog"
-	"sync/atomic"
+	"testing"
+
+	"sneak.berlin/go/neoirc/internal/dbtest"
 )
 
-//nolint:gochecknoglobals // test counter
-var testDBCounter atomic.Int64
-
 // NewTestDatabase creates an in-memory database for testing.
-func NewTestDatabase() (*Database, error) {
-	counter := testDBCounter.Add(1)
+func NewTestDatabase(tb testing.TB) (*Database, error) {
+	tb.Helper()
 
-	dsn := fmt.Sprintf(
-		"file:testdb%d?mode=memory"+
-			"&cache=shared&_pragma=foreign_keys(1)",
-		counter,
-	)
+	dsn := dbtest.NewURL(tb) + "&_pragma=foreign_keys(1)"
 
 	conn, err := sql.Open("sqlite", dsn)
 	if err != nil {

internal/db/queries_test.go

@@ -13,7 +13,7 @@ import (
 func setupTestDB(t *testing.T) *db.Database {
 	t.Helper()
 
-	database, err := db.NewTestDatabase()
+	database, err := db.NewTestDatabase(t)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/dbtest/dbtest.go

@@ -0,0 +1,39 @@
+// Package dbtest gives each test a database of its own. Only tests
+// may import it.
+package dbtest
+
+import (
+	"crypto/rand"
+	"database/sql"
+	"testing"
+
+	_ "modernc.org/sqlite" // registers the sqlite driver
+)
+
+// NewURL returns the URL of a new, empty in-memory database for one
+// test. SQLite deletes an in-memory database when its last connection
+// closes. A pool closes a connection when a query on it is cancelled
+// while it runs. So this function holds a connection of its own open
+// until the test ends.
+func NewURL(tb testing.TB) string {
+	tb.Helper()
+
+	// A random name, so that no other test can share the database.
+	dbURL := "file:" + rand.Text() + "?mode=memory&cache=shared"
+
+	pool, err := sql.Open("sqlite", dbURL)
+	if err != nil {
+		tb.Fatalf("open test database: %v", err)
+	}
+
+	tb.Cleanup(func() { _ = pool.Close() })
+
+	conn, err := pool.Conn(tb.Context())
+	if err != nil {
+		tb.Fatalf("connect to test database: %v", err)
+	}
+
+	tb.Cleanup(func() { _ = conn.Close() })
+
+	return dbURL
+}

internal/handlers/utility_test.go

@@ -1,4 +1,3 @@
-//nolint:paralleltest // global viper, as in api_test.go
 package handlers_test
 
 import (
@@ -72,6 +71,8 @@ func numericBody(
 }
 
 func TestUserhost(t *testing.T) {
+	t.Parallel()
+
 	tserver := newTestServer(t)
 
 	token := tserver.createSession("alice")
@@ -109,6 +110,8 @@ func TestUserhost(t *testing.T) {
 }
 
 func TestVersionAdminInfoTime(t *testing.T) {
+	t.Parallel()
+
 	tserver := newTestServer(t)
 
 	token := tserver.createSession("frank")
@@ -147,6 +150,8 @@ func TestVersionAdminInfoTime(t *testing.T) {
 }
 
 func TestKill(t *testing.T) {
+	t.Parallel()
+
 	tserver := newTestServerWithOper(t)
 
 	victimToken := tserver.createSession("victim")
@@ -213,6 +218,8 @@ func TestKill(t *testing.T) {
 }
 
 func TestWallops(t *testing.T) {
+	t.Parallel()
+
 	tserver := newTestServerWithOper(t)
 
 	receiverToken := tserver.createSession("receiver")
@@ -258,6 +265,8 @@ func TestWallops(t *testing.T) {
 }
 
 func TestUserMode(t *testing.T) {
+	t.Parallel()
+
 	const (
 		nick  = "alice"
 		other = "other"

internal/ircserver/relay.go

@@ -32,8 +32,12 @@ func (c *Conn) relayMessages(ctx context.Context) {
 		// still signals waitCh.
 		waitCh := c.brk.Wait(c.sessionID)
 
-		// Drain any available messages.
-		delivered := c.drainQueue(ctx)
+		// Drain any available messages. The drain ignores the
+		// cancel that comes when the connection ends, because a
+		// query cancelled while it runs leaves the SQLite
+		// connection marked broken, and the pool closes it. The
+		// loop still stops on ctx.
+		delivered := c.drainQueue(context.WithoutCancel(ctx))
 
 		if delivered {
 			c.brk.Remove(c.sessionID, waitCh)

internal/ircserver/server_test.go

@@ -3,7 +3,6 @@ package ircserver_test
 import (
 	"bufio"
 	"context"
-	"crypto/rand"
 	"database/sql"
 	"errors"
 	"fmt"
@@ -20,6 +19,7 @@ import (
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/dbtest"
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/ircserver"
 	"sneak.berlin/go/neoirc/internal/logger"
@@ -107,14 +107,7 @@ func newTestEnvWithResolver(
 ) *testEnv {
 	t.Helper()
 
-	// A random name, so that no other test environment, not
-	// even an earlier run of the same test, can share it.
-	dsn := fmt.Sprintf(
-		"file:%s?mode=memory&cache=shared",
-		rand.Text(),
-	)
-
-	conn, err := sql.Open("sqlite", dsn)
+	conn, err := sql.Open("sqlite", dbtest.NewURL(t))
 	if err != nil {
 		t.Fatalf("open db: %v", err)
 	}
@@ -144,20 +137,6 @@ func newTestEnvWithResolver(
 
 	brk := broker.New()
 
-	var listenConfig net.ListenConfig
-
-	listener, err := listenConfig.Listen(t.Context(), "tcp", "127.0.0.1:0")
-	if err != nil {
-		t.Fatalf("listen: %v", err)
-	}
-
-	addr := listener.Addr().String()
-
-	err = listener.Close()
-	if err != nil {
-		t.Fatalf("close listener: %v", err)
-	}
-
 	log := slog.New(slog.NewTextHandler(
 		os.Stderr,
 		&slog.HandlerOptions{Level: slog.LevelError}, //nolint:exhaustruct
@@ -167,7 +146,9 @@ func newTestEnvWithResolver(
 		log, cfg, database, brk, interval, deadline, resolve,
 	)
 
-	err = srv.Start(addr)
+	// Port 0 makes the system pick a free port. dial reads it
+	// back from the server's listener.
+	err = srv.Start("127.0.0.1:0")
 	if err != nil {
 		t.Fatalf("start irc server: %v", err)
 	}

internal/server/export_test.go

@@ -15,6 +15,12 @@ func NewTestSPAServer() *Server {
 	return srv
 }
 
+// Listener returns the listener the start hook bound for the
+// HTTP server.
+func (srv *Server) Listener() net.Listener {
+	return srv.listener
+}
+
 // ServeUntilShutdown runs serveUntilShutdown, which serves the
 // HTTP server on listener, and returns when it does.
 func (srv *Server) ServeUntilShutdown(listener net.Listener) {

internal/server/server.go

@@ -50,6 +50,7 @@ type Server struct {
 	sentryEnabled bool
 	log           *slog.Logger
 	httpServer    *http.Server
+	listener      net.Listener
 	router        *chi.Mux
 	params        Params
 	mw            *middleware.Middleware
@@ -179,6 +180,8 @@ func (srv *Server) startHTTP(ctx context.Context) error {
 		return fmt.Errorf("http listen: %w", err)
 	}
 
+	srv.listener = listener
+
 	srv.httpServer = &http.Server{ //nolint:exhaustruct // optional fields
 		Addr:           listenAddr,
 		ReadTimeout:    httpReadTimeout,

internal/server/server_test.go

@@ -5,7 +5,6 @@
 package server_test
 
 import (
-	"crypto/rand"
 	"fmt"
 	"net"
 	"net/http"
@@ -19,6 +18,7 @@ import (
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/dbtest"
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/handlers"
 	"sneak.berlin/go/neoirc/internal/healthcheck"
@@ -45,10 +45,9 @@ const (
 // for a long poll the HTTP server is serving to finish, and
 // that the poll gets its response.
 func TestStopWaitsForRequestInProgress(t *testing.T) {
-	port := freePort(t)
-	addr := net.JoinHostPort("127.0.0.1", strconv.Itoa(port))
+	var srv *server.Server
 
-	app, brk, database := startApp(t, port)
+	app, brk, database := startApp(t, fx.Populate(&srv))
 
 	sessionID, _, token, err := database.CreateSession(
 		t.Context(), "poller", "poller", "", "",
@@ -57,9 +56,12 @@ func TestStopWaitsForRequestInProgress(t *testing.T) {
 		t.Fatalf("create session: %v", err)
 	}
 
-	waitUntil(t, "the HTTP server to listen", func() bool {
-		return canConnect(t, addr)
-	})
+	tcpAddr, ok := srv.Listener().Addr().(*net.TCPAddr)
+	if !ok {
+		t.Fatalf("listener address %v is not TCP", srv.Listener().Addr())
+	}
+
+	addr := net.JoinHostPort("127.0.0.1", strconv.Itoa(tcpAddr.Port))
 
 	statuses := make(chan int, 1)
 
@@ -145,7 +147,7 @@ func TestStartFailsWhenHTTPPortIsTaken(t *testing.T) {
 func TestServeFailureStopsApp(t *testing.T) {
 	var srv *server.Server
 
-	app, _, _ := startApp(t, freePort(t), fx.Populate(&srv))
+	app, _, _ := startApp(t, fx.Populate(&srv))
 
 	shutdowns := app.Wait()
 
@@ -168,7 +170,7 @@ func TestServeFailureStopsApp(t *testing.T) {
 func TestServeAfterStopDoesNotStopApp(t *testing.T) {
 	var srv *server.Server
 
-	app, _, _ := startApp(t, freePort(t), fx.Populate(&srv))
+	app, _, _ := startApp(t, fx.Populate(&srv))
 
 	shutdowns := app.Wait()
 
@@ -186,16 +188,15 @@ func TestServeAfterStopDoesNotStopApp(t *testing.T) {
 	}
 }
 
-// startApp starts the app newApp builds, with the HTTP server
-// listening on port.
+// startApp starts the app newApp builds, with the HTTP port
+// set to 0, so the system gives the server a free port.
 func startApp(
 	t *testing.T,
-	port int,
 	options ...fx.Option,
 ) (*fxtest.App, *broker.Broker, *db.Database) {
 	t.Helper()
 
-	app, brk, database := newApp(t, port, options...)
+	app, brk, database := newApp(t, 0, options...)
 
 	app.RequireStart()
 
@@ -241,10 +242,7 @@ func newApp(
 			stats.New,
 		),
 		fx.Decorate(func(cfg *config.Config) *config.Config {
-			// A random name, so that no other test can share it.
-			cfg.DBURL = fmt.Sprintf(
-				"file:%s?mode=memory&cache=shared", rand.Text(),
-			)
+			cfg.DBURL = dbtest.NewURL(t)
 			cfg.Port = port
 
 			return cfg
@@ -257,21 +255,6 @@ func newApp(
 	return app, brk, database
 }
 
-// freePort returns a TCP port that nothing was listening on a
-// moment ago.
-func freePort(t *testing.T) int {
-	t.Helper()
-
-	listener := closedListener(t)
-
-	tcpAddr, ok := listener.Addr().(*net.TCPAddr)
-	if !ok {
-		t.Fatalf("listener address %v is not TCP", listener.Addr())
-	}
-
-	return tcpAddr.Port
-}
-
 // closedListener returns a TCP listener that has already been
 // closed, so that accepting a connection on it fails.
 func closedListener(t *testing.T) net.Listener {
@@ -294,22 +277,6 @@ func closedListener(t *testing.T) net.Listener {
 	return listener
 }
 
-// canConnect reports whether addr accepts a TCP connection.
-func canConnect(t *testing.T, addr string) bool {
-	t.Helper()
-
-	var dialer net.Dialer
-
-	conn, err := dialer.DialContext(t.Context(), "tcp", addr)
-	if err != nil {
-		return false
-	}
-
-	_ = conn.Close()
-
-	return true
-}
-
 // waitUntil calls done every checkStep until it returns true,
 // and fails the test if it does not within testTimeout.
 func waitUntil(t *testing.T, what string, done func() bool) {

internal/service/service_test.go

@@ -6,7 +6,6 @@ package service_test
 
 import (
 	"context"
-	"crypto/rand"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -23,6 +22,7 @@ import (
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/dbtest"
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/hashcash"
 	"sneak.berlin/go/neoirc/internal/logger"
@@ -46,13 +46,7 @@ type testEnv struct {
 func newTestEnv(t *testing.T) *testEnv {
 	t.Helper()
 
-	// A random name, so that no other test can share it, not
-	// even one that has finished but still holds its database
-	// open.
-	dbURL := fmt.Sprintf(
-		"file:%s?mode=memory&cache=shared",
-		rand.Text(),
-	)
+	dbURL := dbtest.NewURL(t)
 
 	var (
 		database *db.Database

web/src/app.jsx

@@ -7,6 +7,11 @@ const RECONNECT_DELAY = 3000;
 const MEMBER_REFRESH_INTERVAL = 10000;
 const ACTION_PREFIX = "\x01ACTION ";
 const ACTION_SUFFIX = "\x01";
+// SERVER_TAB is the Server tab's name, under which its messages and
+// unread count are stored. No nick or channel name can contain *, so a
+// user with the nick Server gets a direct-message tab of its own. The
+// tab bar labels this tab Server.
+const SERVER_TAB = "*server*";
 
 // Hashcash proof-of-work helpers using Web Crypto API.
 
@@ -270,9 +275,9 @@ function UserList({ members, onNickClick }) {
 function App() {
   const [loggedIn, setLoggedIn] = useState(false);
   const [nick, setNick] = useState("");
-  const [tabs, setTabs] = useState([{ type: "server", name: "Server" }]);
+  const [tabs, setTabs] = useState([{ type: "server", name: SERVER_TAB }]);
   const [activeTab, setActiveTab] = useState(0);
-  const [messages, setMessages] = useState({ Server: [] });
+  const [messages, setMessages] = useState({ [SERVER_TAB]: [] });
   const [members, setMembers] = useState({});
   const [topics, setTopics] = useState({});
   const [unread, setUnread] = useState({});
@@ -355,6 +360,26 @@ function App() {
       .catch(() => {});
   }, []);
 
+  // removeChannelTab closes a channel's tab. The tab the user was
+  // reading stays active, found by its name; when it was the closed tab,
+  // the Server tab shows.
+  const removeChannelTab = useCallback((name) => {
+    setTabs((prev) => {
+      const remaining = prev.filter(
+        (t) => !(t.type === "channel" && t.name === name),
+      );
+      // Preact runs this update at once, on the newest active tab.
+      setActiveTab((active) => {
+        const reading = prev[active]?.name;
+        const idx = remaining.findIndex((t) => t.name === reading);
+
+        return idx >= 0 ? idx : 0;
+      });
+
+      return remaining;
+    });
+  }, []);
+
   const processMessage = useCallback(
     (msg) => {
       const body = Array.isArray(msg.body) ? msg.body.join("\n") : "";
@@ -424,6 +449,13 @@ function App() {
           break;
         }
         case "PART": {
+          // The user's own PART, sent from this client or another,
+          // closes the tab and adds no message or unread count.
+          if (msg.from === nickRef.current) {
+            removeChannelTab(msg.to);
+
+            break;
+          }
           const reason = body ? " (" + body + ")" : "";
           const text = `${msg.from} has parted ${msg.to}${reason}`;
           if (msg.to) addMessage(msg.to, { ...base, text, system: true });
@@ -431,6 +463,29 @@ function App() {
 
           break;
         }
+        case "KICK": {
+          // The kicked nick is in params; the body is the reason.
+          const kicked = Array.isArray(msg.params) ? msg.params[0] : "";
+          const reason = body ? " (" + body + ")" : "";
+          const text = `${kicked} was kicked from ${msg.to} by ${msg.from}${reason}`;
+          if (msg.to) addMessage(msg.to, { ...base, text, system: true });
+          if (kicked === nickRef.current) {
+            // The channel's tab closes, so the Server tab gets the line
+            // too. It needs an id of its own: addMessage drops a message
+            // whose id it has already seen.
+            addMessage(SERVER_TAB, {
+              ...base,
+              id: msg.id + "-server",
+              text,
+              system: true,
+            });
+            removeChannelTab(msg.to);
+          } else if (msg.to && msg.to.startsWith("#")) {
+            refreshMembers(msg.to);
+          }
+
+          break;
+        }
         case "QUIT": {
           const reason = body ? " (" + body + ")" : "";
           const text = `${msg.from} has quit${reason}`;
@@ -518,7 +573,7 @@ function App() {
             const chName = msg.params[0];
             const count = msg.params[1];
             const chTopic = body || "";
-            addMessage("Server", {
+            addMessage(SERVER_TAB, {
               ...base,
               text: `${chName} (${count} users): ${chTopic.trim()}`,
               system: true,
@@ -528,7 +583,7 @@ function App() {
           break;
         }
         case 323:
-          addMessage("Server", {
+          addMessage(SERVER_TAB, {
             ...base,
             text: body || "End of channel list",
             system: true,
@@ -541,7 +596,7 @@ function App() {
             const whoCh = msg.params[0];
             const whoNick = msg.params[4];
             const whoFlags = msg.params.length > 5 ? msg.params[5] : "";
-            addMessage("Server", {
+            addMessage(SERVER_TAB, {
               ...base,
               text: `${whoCh} ${whoNick} ${whoFlags}`,
               system: true,
@@ -551,7 +606,7 @@ function App() {
           break;
         }
         case 315:
-          addMessage("Server", {
+          addMessage(SERVER_TAB, {
             ...base,
             text: body || "End of /WHO list",
             system: true,
@@ -562,7 +617,7 @@ function App() {
           // RPL_WHOISUSER — params nick, user, host, *; body realname.
           if (Array.isArray(msg.params) && msg.params.length >= 3) {
             const [wiNick, wiUser, wiHost] = msg.params;
-            addMessage("Server", {
+            addMessage(SERVER_TAB, {
               ...base,
               text: `${wiNick} is ${wiUser}@${wiHost} (${body})`,
               system: true,
@@ -576,7 +631,7 @@ function App() {
           if (Array.isArray(msg.params) && msg.params.length >= 2) {
             const wiNick = msg.params[0];
             const wiServer = msg.params[1];
-            addMessage("Server", {
+            addMessage(SERVER_TAB, {
               ...base,
               text: `${wiNick} on ${wiServer}`,
               system: true,
@@ -588,7 +643,7 @@ function App() {
         case 313: {
           // RPL_WHOISOPERATOR — nick; body "is an IRC operator".
           if (Array.isArray(msg.params) && msg.params.length >= 1) {
-            addMessage("Server", {
+            addMessage(SERVER_TAB, {
               ...base,
               text: `${msg.params[0]} ${body}`,
               system: true,
@@ -602,7 +657,7 @@ function App() {
           if (Array.isArray(msg.params) && msg.params.length >= 3) {
             const [wiNick, idle, signon] = msg.params;
             const signedOn = new Date(Number(signon) * 1000).toLocaleString();
-            addMessage("Server", {
+            addMessage(SERVER_TAB, {
               ...base,
               text: `${wiNick} has been idle ${idle}s, signed on ${signedOn}`,
               system: true,
@@ -615,7 +670,7 @@ function App() {
           // RPL_WHOISCHANNELS — nick, channels.
           if (Array.isArray(msg.params) && msg.params.length >= 1) {
             const wiNick = msg.params[0];
-            addMessage("Server", {
+            addMessage(SERVER_TAB, {
               ...base,
               text: `${wiNick} is on: ${body}`,
               system: true,
@@ -625,7 +680,7 @@ function App() {
           break;
         }
         case 318:
-          addMessage("Server", {
+          addMessage(SERVER_TAB, {
             ...base,
             text: body || "End of /WHOIS list",
             system: true,
@@ -635,7 +690,7 @@ function App() {
         case 324: {
           // RPL_CHANNELMODEIS — channel, mode string.
           if (Array.isArray(msg.params) && msg.params.length >= 2) {
-            addMessage("Server", {
+            addMessage(SERVER_TAB, {
               ...base,
               text: `${msg.params[0]} modes: ${msg.params[1]}`,
               system: true,
@@ -647,16 +702,16 @@ function App() {
         case 375:
         case 372:
         case 376:
-          addMessage("Server", { ...base, text: body, system: true });
+          addMessage(SERVER_TAB, { ...base, text: body, system: true });
 
           break;
         default:
           if (body) {
-            addMessage("Server", { ...base, text: body, system: true });
+            addMessage(SERVER_TAB, { ...base, text: body, system: true });
           }
       }
     },
-    [addMessage, refreshMembers],
+    [addMessage, refreshMembers, removeChannelTab],
   );
 
   // Long-poll loop.
@@ -778,7 +833,7 @@ function App() {
       );
       setNick(userNick);
       setLoggedIn(true);
-      addSystemMessage("Server", `Connected as ${userNick}`);
+      addSystemMessage(SERVER_TAB, `Connected as ${userNick}`);
 
       if (isResumed) {
         // Request MOTD on resumed sessions (new sessions
@@ -802,10 +857,11 @@ function App() {
       // Fresh session — join any previously saved channels.
       for (const ch of saved) {
         try {
-          await api("/messages", {
+          const res = await api("/messages", {
             method: "POST",
             body: JSON.stringify({ command: "JOIN", to: ch }),
           });
+          if (res?.status !== "joined") continue;
           setTabs((prev) => {
             if (prev.find((t) => t.type === "channel" && t.name === ch))
               return prev;
@@ -825,18 +881,30 @@ function App() {
     name = name.trim();
     if (!name.startsWith("#")) name = "#" + name;
     try {
-      await api("/messages", {
+      const res = await api("/messages", {
         method: "POST",
         body: JSON.stringify({ command: "JOIN", to: name }),
       });
+      // A refused join opens no tab. The error numeric that the
+      // server sends to the message queue tells the user why.
+      if (res?.status !== "joined") return;
+      // Show the channel's tab. Preact runs this update at once on the
+      // newest tab list, so the tab is found there by name: the user's
+      // own JOIN event may already have added it, and other tabs may
+      // have closed.
       setTabs((prev) => {
-        if (prev.find((t) => t.type === "channel" && t.name === name))
+        const idx = prev.findIndex(
+          (t) => t.type === "channel" && t.name === name,
+        );
+        if (idx >= 0) {
+          setActiveTab(idx);
+
           return prev;
+        }
+        setActiveTab(prev.length);
 
         return [...prev, { type: "channel", name }];
       });
-      const newIdx = tabsRef.current.length;
-      setActiveTab(newIdx);
       try {
         const hist = await api(
           `/history?target=${encodeURIComponent(name)}&limit=50`,
@@ -849,7 +917,7 @@ function App() {
       }
     } catch (err) {
       addSystemMessage(
-        "Server",
+        SERVER_TAB,
         `Failed to join ${name}: ${err.data?.error || "error"}`,
       );
     }
@@ -865,10 +933,7 @@ function App() {
     } catch (e) {
       // Ignore.
     }
-    setTabs((prev) =>
-      prev.filter((t) => !(t.type === "channel" && t.name === name)),
-    );
-    setActiveTab(0);
+    removeChannelTab(name);
   };
 
   const closeTab = (idx) => {
@@ -883,16 +948,23 @@ function App() {
 
   const openDM = (targetNick) => {
     if (targetNick === nickRef.current) return;
+    // Show the direct-message tab. Preact runs this update at once on
+    // the newest tab list, so the tab is found there by name: the
+    // server's copy of the user's message may already have added it,
+    // and other tabs may have opened or closed.
     setTabs((prev) => {
-      if (prev.find((t) => t.type === "dm" && t.name === targetNick))
+      const idx = prev.findIndex(
+        (t) => t.type === "dm" && t.name === targetNick,
+      );
+      if (idx >= 0) {
+        setActiveTab(idx);
+
         return prev;
+      }
+      setActiveTab(prev.length);
 
       return [...prev, { type: "dm", name: targetNick }];
     });
-    const idx = tabs.findIndex(
-      (t) => t.type === "dm" && t.name === targetNick,
-    );
-    setActiveTab(idx >= 0 ? idx : tabs.length);
   };
 
   const handleCommand = async (text) => {
@@ -903,7 +975,7 @@ function App() {
     switch (cmd) {
       case "/join": {
         if (parts[1]) joinChannel(parts[1]);
-        else addSystemMessage("Server", "Usage: /join #channel");
+        else addSystemMessage(SERVER_TAB, "Usage: /join #channel");
 
         break;
       }
@@ -912,7 +984,7 @@ function App() {
           const reason = parts.slice(1).join(" ") || undefined;
           partChannel(tab.name, reason);
         } else {
-          addSystemMessage("Server", "You are not in a channel");
+          addSystemMessage(SERVER_TAB, "You are not in a channel");
         }
 
         break;
@@ -933,19 +1005,19 @@ function App() {
             openDM(target);
           } catch (err) {
             addSystemMessage(
-              "Server",
+              SERVER_TAB,
               `Message failed: ${err.data?.error || "error"}`,
             );
           }
         } else {
-          addSystemMessage("Server", "Usage: /msg <nick> <message>");
+          addSystemMessage(SERVER_TAB, "Usage: /msg <nick> <message>");
         }
 
         break;
       }
       case "/me": {
         if (tab.type === "server") {
-          addSystemMessage("Server", "Cannot use /me in server window");
+          addSystemMessage(SERVER_TAB, "Cannot use /me in server window");
 
           break;
         }
@@ -967,7 +1039,7 @@ function App() {
             );
           }
         } else {
-          addSystemMessage("Server", "Usage: /me <action>");
+          addSystemMessage(SERVER_TAB, "Usage: /me <action>");
         }
 
         break;
@@ -981,19 +1053,19 @@ function App() {
             });
           } catch (err) {
             addSystemMessage(
-              "Server",
+              SERVER_TAB,
               `Nick change failed: ${err.data?.error || "error"}`,
             );
           }
         } else {
-          addSystemMessage("Server", "Usage: /nick <newnick>");
+          addSystemMessage(SERVER_TAB, "Usage: /nick <newnick>");
         }
 
         break;
       }
       case "/topic": {
         if (tab.type !== "channel") {
-          addSystemMessage("Server", "You are not in a channel");
+          addSystemMessage(SERVER_TAB, "You are not in a channel");
 
           break;
         }
@@ -1010,13 +1082,13 @@ function App() {
             });
           } catch (err) {
             addSystemMessage(
-              "Server",
+              SERVER_TAB,
               `Topic change failed: ${err.data?.error || "error"}`,
             );
           }
         } else {
           addSystemMessage(
-            "Server",
+            SERVER_TAB,
             `Current topic for ${tab.name}: ${topics[tab.name] || "(none)"}`,
           );
         }
@@ -1025,7 +1097,7 @@ function App() {
       }
       case "/mode": {
         if (tab.type !== "channel") {
-          addSystemMessage("Server", "You are not in a channel");
+          addSystemMessage(SERVER_TAB, "You are not in a channel");
 
           break;
         }
@@ -1043,7 +1115,7 @@ function App() {
           });
         } catch (err) {
           addSystemMessage(
-            "Server",
+            SERVER_TAB,
             `MODE failed: ${err.data?.error || "error"}`,
           );
         }
@@ -1074,7 +1146,7 @@ function App() {
           });
         } catch (err) {
           addSystemMessage(
-            "Server",
+            SERVER_TAB,
             `Failed to request MOTD: ${err.data?.error || "error"}`,
           );
         }
@@ -1098,13 +1170,13 @@ function App() {
               });
             } catch (err) {
               addSystemMessage(
-                "Server",
+                SERVER_TAB,
                 `Message failed: ${err.data?.error || "error"}`,
               );
             }
           }
         } else {
-          addSystemMessage("Server", "Usage: /query <nick> [message]");
+          addSystemMessage(SERVER_TAB, "Usage: /query <nick> [message]");
         }
 
         break;
@@ -1117,7 +1189,7 @@ function App() {
           });
         } catch (err) {
           addSystemMessage(
-            "Server",
+            SERVER_TAB,
             `Failed to list channels: ${err.data?.error || "error"}`,
           );
         }
@@ -1134,12 +1206,12 @@ function App() {
             });
           } catch (err) {
             addSystemMessage(
-              "Server",
+              SERVER_TAB,
               `WHO failed: ${err.data?.error || "error"}`,
             );
           }
         } else {
-          addSystemMessage("Server", "Usage: /who #channel");
+          addSystemMessage(SERVER_TAB, "Usage: /who #channel");
         }
 
         break;
@@ -1153,12 +1225,12 @@ function App() {
             });
           } catch (err) {
             addSystemMessage(
-              "Server",
+              SERVER_TAB,
               `WHOIS failed: ${err.data?.error || "error"}`,
             );
           }
         } else {
-          addSystemMessage("Server", "Usage: /whois <nick>");
+          addSystemMessage(SERVER_TAB, "Usage: /whois <nick>");
         }
 
         break;
@@ -1189,13 +1261,13 @@ function App() {
           "  /help                 — Show this help",
         ];
         for (const line of helpLines) {
-          addSystemMessage("Server", line);
+          addSystemMessage(SERVER_TAB, line);
         }
 
         break;
       }
       default:
-        addSystemMessage("Server", `Unknown command: ${cmd}`);
+        addSystemMessage(SERVER_TAB, `Unknown command: ${cmd}`);
     }
   };
 
@@ -1224,7 +1296,7 @@ function App() {
 
     if (tab.type === "server") {
       addSystemMessage(
-        "Server",
+        SERVER_TAB,
         "Cannot send messages to the server window. Use /join #channel first.",
       );
 
@@ -1295,7 +1367,7 @@ function App() {
               key={tab.name}
             >
               <span class="tab-label">
-                {tab.type === "dm" ? tab.name : tab.name}
+                {tab.type === "server" ? "Server" : tab.name}
               </span>
               {unread[tab.name] > 0 && i !== activeTab && (
                 <span class="unread-count">({unread[tab.name]})</span>