Add post image upload backend (#11)

Adds bounded JPEG, PNG, and WebP processing, route-specific multipart limits, attachment mutation handling, and object cleanup on failed persistence or successful removal.

Reviewed-on: #11
Co-authored-by: codegirl-007 <s.raide@gmail.com>

cmd/server/main.go

@@ -17,7 +17,6 @@ import (
 
 	"plumber"
 	"plumber/internal/blob"
-	"plumber/internal/events"
 	"plumber/internal/mail"
 	"plumber/internal/store"
 	"plumber/internal/web"
@@ -35,7 +34,7 @@ func main() {
 	if err != nil {
 		log.Fatalf("mail: %v", err)
 	}
-	handler := newHandler(db, sessions, uploader, notifier, events.New())
+	handler := newHandler(db, sessions, uploader, notifier)
 	run(&http.Server{
 		Addr:              listenAddr(),
 		Handler:           handler,
@@ -59,15 +58,13 @@ func openDB() (*sql.DB, *store.SessionStore) {
 	return db, sessions
 }
 
-func newHandler(db *sql.DB, sessions *store.SessionStore, uploader blob.Uploader, notifier mail.Notifier, bus events.Publisher) http.Handler {
+func newHandler(db *sql.DB, sessions *store.SessionStore, uploader blob.Uploader, notifier mail.Notifier) http.Handler {
 	srv, err := web.New(store.NewPostgres(db), sessions.Store(), plumber.TemplateFS, plumber.StaticFS, web.Config{
 		AdminSetupSecret: strings.TrimSpace(os.Getenv("ADMIN_SETUP_SECRET")),
 		SecureCookie:     secureCookieFromEnv(),
 		TrustedProxies:   parseTrustedProxies(os.Getenv("TRUSTED_PROXY_CIDRS")),
 		Blob:             uploader,
 		Mail:             notifier,
-		Events:           bus,
-		BaseURL:          strings.TrimRight(strings.TrimSpace(os.Getenv("APP_BASE_URL")), "/"),
 	})
 	if err != nil {
 		log.Fatalf("server: %v", err)

go.mod

@@ -11,6 +11,7 @@ require (
 	github.com/google/uuid v1.6.0
 	github.com/jackc/pgx/v5 v5.10.0
 	github.com/joho/godotenv v1.5.1
+	github.com/rwcarlsen/goexif v0.0.0-20190401172101-9e8deecbddbd
 	golang.org/x/crypto v0.55.0
 	golang.org/x/image v0.45.0
 )

go.sum

@@ -45,6 +45,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/resend/resend-go/v3 v3.16.0 h1:t0Z/7k2sxnJGw8SjsCM9O8qkq3YRRHzTxWQNjhF2KhE=
 github.com/resend/resend-go/v3 v3.16.0/go.mod h1:iI7VA0NoGjWvsNii5iNC5Dy0llsI3HncXPejhniYzwE=
+github.com/rwcarlsen/goexif v0.0.0-20190401172101-9e8deecbddbd h1:CmH9+J6ZSsIjUK3dcGsnCnO41eRBOnY12zwkn5qVwgc=
+github.com/rwcarlsen/goexif v0.0.0-20190401172101-9e8deecbddbd/go.mod h1:hPqNNc0+uJM6H+SuU8sEs5K5IQeKccPqeSjfgcKGgPk=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=

internal/events/bus.go

@@ -1,79 +0,0 @@
-package events
-
-import (
-	"context"
-	"log"
-	"sync"
-)
-
-const defaultBuffer = 64
-
-// Publisher is the site-facing write side of the bus.
-type Publisher interface {
-	Publish(ctx context.Context, ev any)
-}
-
-// Bus is an in-process pub/sub with one worker and a bounded queue.
-type Bus struct {
-	ch     chan any
-	mu     sync.Mutex
-	subs   []func(context.Context, any)
-	closed sync.Once
-}
-
-// New starts a worker that delivers events to subscribers in publish order.
-func New() *Bus {
-	return newBus(defaultBuffer, true)
-}
-
-func newBus(buffer int, start bool) *Bus {
-	if buffer < 1 {
-		buffer = 1
-	}
-	b := &Bus{ch: make(chan any, buffer)}
-	if start {
-		go b.loop()
-	}
-	return b
-}
-
-// Publish enqueues ev. It never blocks the caller; a full buffer is dropped.
-func (b *Bus) Publish(_ context.Context, ev any) {
-	if b == nil {
-		return
-	}
-	select {
-	case b.ch <- ev:
-	default:
-		log.Printf("events: dropped %T", ev)
-	}
-}
-
-// Subscribe adds a handler. Handlers run serially on the worker.
-func (b *Bus) Subscribe(fn func(context.Context, any)) {
-	if b == nil || fn == nil {
-		return
-	}
-	b.mu.Lock()
-	b.subs = append(b.subs, fn)
-	b.mu.Unlock()
-}
-
-func (b *Bus) loop() {
-	for ev := range b.ch {
-		b.mu.Lock()
-		subs := append([]func(context.Context, any){}, b.subs...)
-		b.mu.Unlock()
-		for _, fn := range subs {
-			fn(context.Background(), ev)
-		}
-	}
-}
-
-// Close stops the worker. Safe to call more than once.
-func (b *Bus) Close() {
-	if b == nil {
-		return
-	}
-	b.closed.Do(func() { close(b.ch) })
-}

internal/events/bus_test.go

@@ -1,104 +0,0 @@
-package events
-
-import (
-	"context"
-	"sync"
-	"testing"
-	"time"
-)
-
-func TestPermalink(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		base, root, post, want string
-	}{
-		{"", "root-1", "post-2", "/questions/root-1#post-post-2"},
-		{"https://www.askaplumberfirst.com/", "root-1", "post-2", "https://www.askaplumberfirst.com/questions/root-1#post-post-2"},
-		{"https://www.askaplumberfirst.com", "a b", "c/d", "https://www.askaplumberfirst.com/questions/a%20b#post-c%2Fd"},
-	}
-	for _, tc := range tests {
-		if got := Permalink(tc.base, tc.root, tc.post); got != tc.want {
-			t.Fatalf("Permalink(%q, %q, %q) = %q, want %q", tc.base, tc.root, tc.post, got, tc.want)
-		}
-	}
-}
-
-func TestNopAndRecording(t *testing.T) {
-	t.Parallel()
-
-	Nop{}.Publish(context.Background(), PostCreated{})
-
-	rec := &Recording{}
-	rec.Publish(context.Background(), PostCreated{PostEvent: PostEvent{PostID: "a"}})
-	rec.Publish(context.Background(), PostUpdated{PostEvent: PostEvent{PostID: "b"}})
-	if rec.Len() != 2 {
-		t.Fatalf("len = %d", rec.Len())
-	}
-	got := rec.Snapshot()
-	created, ok := got[0].(PostCreated)
-	if !ok || created.PostID != "a" {
-		t.Fatalf("first = %#v", got[0])
-	}
-	updated, ok := got[1].(PostUpdated)
-	if !ok || updated.PostID != "b" {
-		t.Fatalf("second = %#v", got[1])
-	}
-}
-
-func TestBusDeliversInOrder(t *testing.T) {
-	t.Parallel()
-
-	bus := New()
-	defer bus.Close()
-
-	var mu sync.Mutex
-	var got []string
-	done := make(chan struct{})
-	bus.Subscribe(func(_ context.Context, ev any) {
-		mu.Lock()
-		got = append(got, ev.(string))
-		if len(got) == 3 {
-			close(done)
-		}
-		mu.Unlock()
-	})
-
-	ctx := context.Background()
-	bus.Publish(ctx, "one")
-	bus.Publish(ctx, "two")
-	bus.Publish(ctx, "three")
-
-	select {
-	case <-done:
-	case <-time.After(time.Second):
-		t.Fatal("timed out waiting for events")
-	}
-	mu.Lock()
-	defer mu.Unlock()
-	if len(got) != 3 || got[0] != "one" || got[1] != "two" || got[2] != "three" {
-		t.Fatalf("got %v", got)
-	}
-}
-
-func TestBusDropsWhenFull(t *testing.T) {
-	t.Parallel()
-
-	bus := newBus(1, false)
-	bus.Publish(context.Background(), "kept")
-	bus.Publish(context.Background(), "dropped")
-
-	select {
-	case ev := <-bus.ch:
-		if ev != "kept" {
-			t.Fatalf("got %v", ev)
-		}
-	default:
-		t.Fatal("expected buffered event")
-	}
-	select {
-	case ev := <-bus.ch:
-		t.Fatalf("unexpected extra event %v", ev)
-	default:
-	}
-}

internal/events/event.go

@@ -1,47 +0,0 @@
-package events
-
-import (
-	"net/url"
-	"strings"
-)
-
-// Image is a public photo already attached to a site post.
-type Image struct {
-	URL         string
-	Description string
-}
-
-// PostEvent is a Discord-free snapshot of a site post after a successful write.
-type PostEvent struct {
-	PostID     string
-	RootID     string
-	ParentID   string
-	Title      string
-	Body       string
-	City       string
-	AuthorID   string
-	AuthorName string
-	AuthorRole string
-	Images     []Image
-	Permalink  string
-}
-
-// PostCreated is emitted after a successful site create.
-type PostCreated struct {
-	PostEvent
-}
-
-// PostUpdated is emitted after a successful site edit.
-type PostUpdated struct {
-	PostEvent
-}
-
-// Permalink builds /questions/{root}#post-{id}, prefixed by baseURL when set.
-func Permalink(baseURL, rootID, postID string) string {
-	path := "/questions/" + url.PathEscape(rootID) + "#post-" + url.PathEscape(postID)
-	base := strings.TrimRight(strings.TrimSpace(baseURL), "/")
-	if base == "" {
-		return path
-	}
-	return base + path
-}

internal/events/nop.go

@@ -1,9 +0,0 @@
-package events
-
-import "context"
-
-// Nop is a Publisher used when nothing is subscribed.
-type Nop struct{}
-
-// Publish discards ev.
-func (Nop) Publish(context.Context, any) {}

internal/events/recording.go

@@ -1,44 +0,0 @@
-package events
-
-import (
-	"context"
-	"sync"
-)
-
-// Recording is a test Publisher that records events synchronously.
-type Recording struct {
-	mu  sync.Mutex
-	evs []any
-}
-
-// Publish appends ev.
-func (r *Recording) Publish(_ context.Context, ev any) {
-	if r == nil {
-		return
-	}
-	r.mu.Lock()
-	defer r.mu.Unlock()
-	r.evs = append(r.evs, ev)
-}
-
-// Len returns the number of recorded events.
-func (r *Recording) Len() int {
-	if r == nil {
-		return 0
-	}
-	r.mu.Lock()
-	defer r.mu.Unlock()
-	return len(r.evs)
-}
-
-// Snapshot returns a copy of recorded events.
-func (r *Recording) Snapshot() []any {
-	if r == nil {
-		return nil
-	}
-	r.mu.Lock()
-	defer r.mu.Unlock()
-	out := make([]any, len(r.evs))
-	copy(out, r.evs)
-	return out
-}

internal/web/events.go

@@ -1,65 +0,0 @@
-package web
-
-import (
-	"context"
-
-	"plumber/internal/events"
-	"plumber/internal/store"
-)
-
-func (s *Server) publishPostCreated(post, root *store.Post, author *store.User) {
-	s.publishPost(events.PostCreated{PostEvent: s.postEvent(post, root, author)}, root)
-}
-
-func (s *Server) publishPostUpdated(post, root *store.Post, author *store.User) {
-	s.publishPost(events.PostUpdated{PostEvent: s.postEvent(post, root, author)}, root)
-}
-
-func (s *Server) publishPost(ev any, root *store.Post) {
-	if root != nil && root.PostState == store.PostStateHidden {
-		return
-	}
-	s.cfg.Events.Publish(context.Background(), ev)
-}
-
-func (s *Server) postEvent(post, root *store.Post, author *store.User) events.PostEvent {
-	if post == nil {
-		return events.PostEvent{}
-	}
-	rootID := post.ID
-	if root != nil {
-		rootID = root.ID
-	}
-	ev := events.PostEvent{
-		PostID:     post.ID,
-		RootID:     rootID,
-		Title:      post.Title,
-		Body:       post.Body,
-		City:       post.City,
-		AuthorID:   post.AuthorID,
-		AuthorName: post.AuthorName,
-		AuthorRole: string(post.AuthorRole),
-		Permalink:  events.Permalink(s.cfg.BaseURL, rootID, post.ID),
-	}
-	if post.ParentID != nil {
-		ev.ParentID = *post.ParentID
-	}
-	if author != nil {
-		if ev.AuthorName == "" {
-			ev.AuthorName = author.Name
-		}
-		if ev.AuthorRole == "" {
-			ev.AuthorRole = string(author.Role)
-		}
-	}
-	if n := len(post.Images); n > 0 {
-		ev.Images = make([]events.Image, 0, n)
-		for _, img := range post.Images {
-			ev.Images = append(ev.Images, events.Image{
-				URL:         img.PublicURL,
-				Description: img.Description,
-			})
-		}
-	}
-	return ev
-}

internal/web/events_test.go

@@ -1,238 +0,0 @@
-package web
-
-import (
-	"context"
-	"encoding/json"
-	"net/http"
-	"net/url"
-	"strings"
-	"testing"
-
-	"plumber/internal/events"
-	"plumber/internal/pacific"
-	"plumber/internal/store"
-)
-
-func TestPostHandlersPublishEvents(t *testing.T) {
-	t.Parallel()
-
-	rec := &events.Recording{}
-	srv, mem := newTestServer(t, Config{
-		Events:  rec,
-		BaseURL: "https://www.askaplumberfirst.com",
-	})
-	handler := srv.Handler()
-	homeowner := seedUser(t, mem, uniq("homeowner"), "hunter22", store.RoleUser)
-	admin := seedUser(t, mem, uniq("admin"), "hunter22", store.RoleAdmin)
-	homeownerCookies := loginUser(t, handler, homeowner.Username, "hunter22")
-	adminCookies := loginUser(t, handler, admin.Username, "hunter22")
-	homeownerCSRF := csrfForCookies(t, handler, homeownerCookies)
-	adminCSRF := csrfForCookies(t, handler, adminCookies)
-
-	submit := postForm(handler, "/submit", url.Values{
-		"_csrf": {homeownerCSRF},
-		"title": {"Leaky sink"},
-		"body":  {"Water under the cabinet."},
-		"city":  {"Oakland"},
-	}, homeownerCookies)
-	if submit.Code != http.StatusSeeOther {
-		t.Fatalf("submit status = %d: %s", submit.Code, submit.Body.String())
-	}
-
-	create := postForm(handler, "/posts", url.Values{
-		"_csrf": {homeownerCSRF},
-		"title": {"Second question"},
-		"body":  {"Another leak."},
-		"city":  {"Berkeley"},
-	}, homeownerCookies)
-	if create.Code != http.StatusSeeOther {
-		t.Fatalf("create status = %d: %s", create.Code, create.Body.String())
-	}
-
-	roots, err := mem.ListRootPosts(context.Background(), pacific.Today(), homeowner.ID)
-	if err != nil || len(roots) != 2 {
-		t.Fatalf("roots = %+v, %v", roots, err)
-	}
-	var submitRoot, createRoot store.Post
-	for _, root := range roots {
-		switch root.Title {
-		case "Leaky sink":
-			submitRoot = root
-		case "Second question":
-			createRoot = root
-		}
-	}
-	if submitRoot.ID == "" || createRoot.ID == "" {
-		t.Fatalf("missing created roots: %+v", roots)
-	}
-
-	reply := postForm(handler, "/posts", url.Values{
-		"_csrf":     {adminCSRF},
-		"parent_id": {createRoot.ID},
-		"body":      {"Replace the cartridge."},
-	}, adminCookies)
-	if reply.Code != http.StatusSeeOther {
-		t.Fatalf("reply status = %d: %s", reply.Code, reply.Body.String())
-	}
-	thread, err := mem.GetPostThread(context.Background(), createRoot.ID)
-	if err != nil || len(thread.Replies) != 1 {
-		t.Fatalf("thread = %+v, %v", thread, err)
-	}
-	adminReply := thread.Replies[0]
-
-	edit := postForm(handler, "/posts/"+createRoot.ID+"/edit", url.Values{
-		"_csrf": {homeownerCSRF},
-		"body":  {"Updated leak description."},
-	}, homeownerCookies)
-	if edit.Code != http.StatusSeeOther {
-		t.Fatalf("edit status = %d: %s", edit.Code, edit.Body.String())
-	}
-
-	empty := postForm(handler, "/posts", url.Values{
-		"_csrf": {homeownerCSRF},
-		"title": {"Missing body"},
-	}, homeownerCookies)
-	if empty.Code != http.StatusBadRequest {
-		t.Fatalf("empty body status = %d, want 400", empty.Code)
-	}
-
-	hidden := &store.Post{
-		AuthorID:  homeowner.ID,
-		Title:     "Hidden thread",
-		Body:      "Not public.",
-		PostDate:  pacific.Today(),
-		PostState: store.PostStateHidden,
-	}
-	if err := mem.CreatePost(context.Background(), hidden); err != nil {
-		t.Fatal(err)
-	}
-	hiddenReply := postForm(handler, "/posts", url.Values{
-		"_csrf":     {homeownerCSRF},
-		"parent_id": {hidden.ID},
-		"body":      {"Should not publish."},
-	}, homeownerCookies)
-	if hiddenReply.Code != http.StatusNotFound {
-		t.Fatalf("hidden reply status = %d, want 404", hiddenReply.Code)
-	}
-	hiddenEdit := postForm(handler, "/posts/"+hidden.ID+"/edit", url.Values{
-		"_csrf": {homeownerCSRF},
-		"body":  {"Still hidden."},
-	}, homeownerCookies)
-	if hiddenEdit.Code != http.StatusSeeOther {
-		t.Fatalf("hidden edit status = %d: %s", hiddenEdit.Code, hiddenEdit.Body.String())
-	}
-
-	got := rec.Snapshot()
-	if len(got) != 4 {
-		t.Fatalf("published %d events, want 4: %#v", len(got), got)
-	}
-
-	submitEv, ok := got[0].(events.PostCreated)
-	if !ok {
-		t.Fatalf("first event %T, want PostCreated", got[0])
-	}
-	assertPostEvent(t, submitEv.PostEvent, events.PostEvent{
-		PostID:     submitRoot.ID,
-		RootID:     submitRoot.ID,
-		Title:      "Leaky sink",
-		Body:       "Water under the cabinet.",
-		City:       "Oakland",
-		AuthorID:   homeowner.ID,
-		AuthorName: homeowner.Name,
-		AuthorRole: string(store.RoleUser),
-		Permalink:  "https://www.askaplumberfirst.com/questions/" + submitRoot.ID + "#post-" + submitRoot.ID,
-	})
-
-	createEv, ok := got[1].(events.PostCreated)
-	if !ok {
-		t.Fatalf("second event %T, want PostCreated", got[1])
-	}
-	assertPostEvent(t, createEv.PostEvent, events.PostEvent{
-		PostID:     createRoot.ID,
-		RootID:     createRoot.ID,
-		Title:      "Second question",
-		Body:       "Another leak.",
-		City:       "Berkeley",
-		AuthorID:   homeowner.ID,
-		AuthorName: homeowner.Name,
-		AuthorRole: string(store.RoleUser),
-		Permalink:  "https://www.askaplumberfirst.com/questions/" + createRoot.ID + "#post-" + createRoot.ID,
-	})
-
-	replyEv, ok := got[2].(events.PostCreated)
-	if !ok {
-		t.Fatalf("third event %T, want PostCreated", got[2])
-	}
-	assertPostEvent(t, replyEv.PostEvent, events.PostEvent{
-		PostID:     adminReply.ID,
-		RootID:     createRoot.ID,
-		ParentID:   createRoot.ID,
-		Body:       "Replace the cartridge.",
-		AuthorID:   admin.ID,
-		AuthorName: admin.Name,
-		AuthorRole: string(store.RoleAdmin),
-		Permalink:  "https://www.askaplumberfirst.com/questions/" + createRoot.ID + "#post-" + adminReply.ID,
-	})
-
-	editEv, ok := got[3].(events.PostUpdated)
-	if !ok {
-		t.Fatalf("fourth event %T, want PostUpdated", got[3])
-	}
-	assertPostEvent(t, editEv.PostEvent, events.PostEvent{
-		PostID:     createRoot.ID,
-		RootID:     createRoot.ID,
-		Title:      "Second question",
-		Body:       "Updated leak description.",
-		City:       "Berkeley",
-		AuthorID:   homeowner.ID,
-		AuthorName: homeowner.Name,
-		AuthorRole: string(store.RoleUser),
-		Permalink:  "https://www.askaplumberfirst.com/questions/" + createRoot.ID + "#post-" + createRoot.ID,
-	})
-
-	for i, ev := range got {
-		raw, err := json.Marshal(ev)
-		if err != nil {
-			t.Fatal(err)
-		}
-		if strings.Contains(strings.ToLower(string(raw)), "discord") {
-			t.Fatalf("event %d contains discord fields: %s", i, raw)
-		}
-	}
-}
-
-func TestStoreCreateDoesNotPublish(t *testing.T) {
-	t.Parallel()
-
-	rec := &events.Recording{}
-	_, mem := newTestServer(t, Config{Events: rec})
-	homeowner := seedUser(t, mem, uniq("homeowner"), "hunter22", store.RoleUser)
-	if err := mem.CreatePost(context.Background(), &store.Post{
-		AuthorID: homeowner.ID,
-		Title:    "Direct write",
-		Body:     "No handler.",
-		PostDate: pacific.Today(),
-	}); err != nil {
-		t.Fatal(err)
-	}
-	if rec.Len() != 0 {
-		t.Fatalf("store.CreatePost published %d events", rec.Len())
-	}
-}
-
-func assertPostEvent(t *testing.T, got, want events.PostEvent) {
-	t.Helper()
-	if got.PostID != want.PostID ||
-		got.RootID != want.RootID ||
-		got.ParentID != want.ParentID ||
-		got.Title != want.Title ||
-		got.Body != want.Body ||
-		got.City != want.City ||
-		got.AuthorID != want.AuthorID ||
-		got.AuthorName != want.AuthorName ||
-		got.AuthorRole != want.AuthorRole ||
-		got.Permalink != want.Permalink ||
-		len(got.Images) != 0 {
-		t.Fatalf("event = %+v, want %+v", got, want)
-	}
-}

internal/web/post_images.go

@@ -0,0 +1,395 @@
+package web
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"image"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"log"
+	"mime"
+	"mime/multipart"
+	"net/http"
+	"path"
+	"strings"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/rwcarlsen/goexif/exif"
+	"golang.org/x/image/draw"
+	_ "golang.org/x/image/webp"
+
+	"plumber/internal/blob"
+	"plumber/internal/store"
+)
+
+const (
+	defaultRequestBodyBytes  = 3 << 20
+	postImageMaxFileBytes    = 5 << 20
+	postImageMaxRequestBytes = 22 << 20
+	postImageMultipartMemory = 2 << 20
+	postImageMaxSourceDim    = 6000
+	postImageMaxSourcePixels = 16_000_000
+	postImageMaxRenderedDim  = 1600
+	postImageCleanupTimeout  = 10 * time.Second
+)
+
+func requestBodyLimit(r *http.Request) int64 {
+	if r.Method != http.MethodPost {
+		return defaultRequestBodyBytes
+	}
+	switch {
+	case r.URL.Path == "/submit", r.URL.Path == "/posts":
+		return postImageMaxRequestBytes
+	case strings.HasPrefix(r.URL.Path, "/posts/") && strings.HasSuffix(r.URL.Path, "/edit"):
+		return postImageMaxRequestBytes
+	default:
+		return defaultRequestBodyBytes
+	}
+}
+
+type postImageRequestError struct {
+	status  int
+	message string
+	cause   error
+}
+
+func (e *postImageRequestError) Error() string {
+	if e.cause == nil {
+		return e.message
+	}
+	return e.message + ": " + e.cause.Error()
+}
+
+func parsePostMutationForm(w http.ResponseWriter, r *http.Request) (func(), bool) {
+	contentType := r.Header.Get("Content-Type")
+	mediaType, _, err := mime.ParseMediaType(contentType)
+	if err != nil && strings.HasPrefix(strings.ToLower(contentType), "multipart/") {
+		http.Error(w, "Could not read image upload.", http.StatusBadRequest)
+		return func() {}, false
+	}
+	if mediaType != "multipart/form-data" {
+		if err := r.ParseForm(); err != nil {
+			writePostImageRequestError(w, err)
+			return func() {}, false
+		}
+		return func() {}, true
+	}
+	if err := r.ParseMultipartForm(postImageMultipartMemory); err != nil {
+		writePostImageRequestError(w, err)
+		return func() {}, false
+	}
+	cleanup := func() {
+		if r.MultipartForm != nil {
+			_ = r.MultipartForm.RemoveAll()
+		}
+	}
+	return cleanup, true
+}
+
+func writePostImageRequestError(w http.ResponseWriter, err error) {
+	var requestErr *postImageRequestError
+	if errors.As(err, &requestErr) {
+		http.Error(w, requestErr.message, requestErr.status)
+		return
+	}
+	var maxErr *http.MaxBytesError
+	if errors.As(err, &maxErr) {
+		http.Error(w, "Image upload is too large.", http.StatusRequestEntityTooLarge)
+		return
+	}
+	http.Error(w, "Could not read image upload.", http.StatusBadRequest)
+}
+
+func (s *Server) postImagesFromForm(
+	ctx context.Context,
+	r *http.Request,
+	postID string,
+	existing []store.PostImage,
+) ([]store.PostImage, []string, error) {
+	if r.MultipartForm == nil {
+		return append([]store.PostImage(nil), existing...), nil, nil
+	}
+	retained, err := retainedPostImages(r.MultipartForm, existing)
+	if err != nil {
+		return nil, nil, err
+	}
+	files := r.MultipartForm.File["images"]
+	descriptions := r.MultipartForm.Value["image_description"]
+	if len(descriptions) > len(files) {
+		return nil, nil, invalidPostImage("Image descriptions do not match selected images.", nil)
+	}
+	if len(retained)+len(files) > store.MaxPostImages {
+		return nil, nil, invalidPostImage("You can attach up to 4 images.", nil)
+	}
+	if len(files) > 0 && !s.cfg.Blob.Enabled() {
+		return nil, nil, &postImageRequestError{
+			status:  http.StatusServiceUnavailable,
+			message: "Image uploads are not configured on this server.",
+		}
+	}
+
+	images := append([]store.PostImage(nil), retained...)
+	newKeys := make([]string, 0, len(files))
+	for i, header := range files {
+		description := ""
+		if i < len(descriptions) {
+			description = strings.TrimSpace(descriptions[i])
+		}
+		if len([]rune(description)) > store.MaxImageDescriptionRunes {
+			s.deletePostImageObjects(newKeys)
+			return nil, nil, invalidPostImage("Image descriptions must be 500 characters or fewer.", nil)
+		}
+		prepared, err := preparePostImage(header)
+		if err != nil {
+			s.deletePostImageObjects(newKeys)
+			return nil, nil, err
+		}
+		imageID := uuid.NewString()
+		objectKey := path.Join("post-images", postID, imageID+prepared.extension)
+		publicURL, err := s.cfg.Blob.Upload(ctx, blob.FileUpload{
+			Key:         objectKey,
+			Body:        bytes.NewReader(prepared.body),
+			ContentType: prepared.contentType,
+			Size:        int64(len(prepared.body)),
+		})
+		if err != nil {
+			s.deletePostImageObjects(newKeys)
+			return nil, nil, &postImageRequestError{
+				status:  http.StatusServiceUnavailable,
+				message: "Could not upload image. Try again later.",
+				cause:   err,
+			}
+		}
+		newKeys = append(newKeys, objectKey)
+		images = append(images, store.PostImage{
+			ID:          imageID,
+			PostID:      postID,
+			ObjectKey:   objectKey,
+			PublicURL:   publicURL,
+			Description: description,
+			Width:       prepared.width,
+			Height:      prepared.height,
+		})
+	}
+	return images, newKeys, nil
+}
+
+func retainedPostImages(form *multipart.Form, existing []store.PostImage) ([]store.PostImage, error) {
+	byID := make(map[string]store.PostImage, len(existing))
+	for _, image := range existing {
+		byID[image.ID] = image
+	}
+	ids := form.Value["existing_image_id"]
+	descriptions := form.Value["existing_image_description"]
+	if len(descriptions) > len(ids) {
+		return nil, invalidPostImage("Existing image descriptions do not match the images.", nil)
+	}
+	seen := make(map[string]bool, len(ids))
+	retained := make([]store.PostImage, 0, len(ids))
+	for i, id := range ids {
+		id = strings.TrimSpace(id)
+		image, ok := byID[id]
+		if !ok || seen[id] {
+			return nil, invalidPostImage("An existing image selection is invalid.", nil)
+		}
+		seen[id] = true
+		if i < len(descriptions) {
+			image.Description = strings.TrimSpace(descriptions[i])
+		}
+		if len([]rune(image.Description)) > store.MaxImageDescriptionRunes {
+			return nil, invalidPostImage("Image descriptions must be 500 characters or fewer.", nil)
+		}
+		retained = append(retained, image)
+	}
+	return retained, nil
+}
+
+func invalidPostImage(message string, cause error) error {
+	return &postImageRequestError{status: http.StatusBadRequest, message: message, cause: cause}
+}
+
+type preparedPostImage struct {
+	body        []byte
+	extension   string
+	contentType string
+	width       int
+	height      int
+}
+
+func preparePostImage(header *multipart.FileHeader) (preparedPostImage, error) {
+	if header == nil {
+		return preparedPostImage{}, invalidPostImage("Select a valid image.", nil)
+	}
+	if header.Size > postImageMaxFileBytes {
+		return preparedPostImage{}, &postImageRequestError{
+			status:  http.StatusRequestEntityTooLarge,
+			message: "Each image must be 5 MB or smaller.",
+		}
+	}
+	file, err := header.Open()
+	if err != nil {
+		return preparedPostImage{}, invalidPostImage("Could not read image.", err)
+	}
+	defer file.Close()
+	raw, err := io.ReadAll(io.LimitReader(file, postImageMaxFileBytes+1))
+	if err != nil {
+		return preparedPostImage{}, invalidPostImage("Could not read image.", err)
+	}
+	if len(raw) == 0 {
+		return preparedPostImage{}, invalidPostImage("Images cannot be empty.", nil)
+	}
+	if int64(len(raw)) > postImageMaxFileBytes {
+		return preparedPostImage{}, &postImageRequestError{
+			status:  http.StatusRequestEntityTooLarge,
+			message: "Each image must be 5 MB or smaller.",
+		}
+	}
+	sniffed := http.DetectContentType(raw)
+	switch sniffed {
+	case "image/jpeg", "image/png", "image/webp":
+	default:
+		return preparedPostImage{}, invalidPostImage("Images must be JPEG, PNG, or WebP.", nil)
+	}
+	cfg, format, err := image.DecodeConfig(bytes.NewReader(raw))
+	if err != nil {
+		return preparedPostImage{}, invalidPostImage("Could not decode image.", err)
+	}
+	if cfg.Width <= 0 || cfg.Height <= 0 ||
+		cfg.Width > postImageMaxSourceDim || cfg.Height > postImageMaxSourceDim ||
+		int64(cfg.Width)*int64(cfg.Height) > postImageMaxSourcePixels {
+		return preparedPostImage{}, invalidPostImage("Image dimensions are too large.", nil)
+	}
+	decoded, decodedFormat, err := image.Decode(bytes.NewReader(raw))
+	if err != nil {
+		return preparedPostImage{}, invalidPostImage("Could not decode image.", err)
+	}
+	if format != "" {
+		decodedFormat = format
+	}
+	if sniffed == "image/jpeg" {
+		decoded = orientPostImage(decoded, jpegOrientation(raw))
+	}
+	decoded = fitPostImage(decoded, postImageMaxRenderedDim)
+
+	var out bytes.Buffer
+	result := preparedPostImage{}
+	switch decodedFormat {
+	case "jpeg":
+		if err := jpeg.Encode(&out, decoded, &jpeg.Options{Quality: 85}); err != nil {
+			return preparedPostImage{}, invalidPostImage("Could not encode image.", err)
+		}
+		result.extension = ".jpg"
+		result.contentType = "image/jpeg"
+	case "png", "webp":
+		if err := png.Encode(&out, decoded); err != nil {
+			return preparedPostImage{}, invalidPostImage("Could not encode image.", err)
+		}
+		result.extension = ".png"
+		result.contentType = "image/png"
+	default:
+		return preparedPostImage{}, invalidPostImage("Images must be JPEG, PNG, or WebP.", nil)
+	}
+	result.body = out.Bytes()
+	result.width = decoded.Bounds().Dx()
+	result.height = decoded.Bounds().Dy()
+	return result, nil
+}
+
+func jpegOrientation(raw []byte) int {
+	metadata, err := exif.Decode(bytes.NewReader(raw))
+	if err != nil {
+		return 1
+	}
+	tag, err := metadata.Get(exif.Orientation)
+	if err != nil {
+		return 1
+	}
+	orientation, err := tag.Int(0)
+	if err != nil || orientation < 1 || orientation > 8 {
+		return 1
+	}
+	return orientation
+}
+
+func orientPostImage(source image.Image, orientation int) image.Image {
+	if orientation <= 1 || orientation > 8 {
+		return source
+	}
+	bounds := source.Bounds()
+	width, height := bounds.Dx(), bounds.Dy()
+	targetWidth, targetHeight := width, height
+	if orientation >= 5 {
+		targetWidth, targetHeight = height, width
+	}
+	target := image.NewNRGBA(image.Rect(0, 0, targetWidth, targetHeight))
+	for y := 0; y < targetHeight; y++ {
+		for x := 0; x < targetWidth; x++ {
+			sourceX, sourceY := x, y
+			switch orientation {
+			case 2:
+				sourceX = width - 1 - x
+			case 3:
+				sourceX, sourceY = width-1-x, height-1-y
+			case 4:
+				sourceY = height - 1 - y
+			case 5:
+				sourceX, sourceY = y, x
+			case 6:
+				sourceX, sourceY = y, height-1-x
+			case 7:
+				sourceX, sourceY = width-1-y, height-1-x
+			case 8:
+				sourceX, sourceY = width-1-y, x
+			}
+			target.Set(x, y, source.At(bounds.Min.X+sourceX, bounds.Min.Y+sourceY))
+		}
+	}
+	return target
+}
+
+func fitPostImage(source image.Image, maxDimension int) image.Image {
+	bounds := source.Bounds()
+	width, height := bounds.Dx(), bounds.Dy()
+	if width <= maxDimension && height <= maxDimension {
+		return source
+	}
+	scale := float64(maxDimension) / float64(width)
+	if float64(height)*scale > float64(maxDimension) {
+		scale = float64(maxDimension) / float64(height)
+	}
+	targetWidth := max(1, int(float64(width)*scale))
+	targetHeight := max(1, int(float64(height)*scale))
+	target := image.NewNRGBA(image.Rect(0, 0, targetWidth, targetHeight))
+	draw.CatmullRom.Scale(target, target.Bounds(), source, bounds, draw.Over, nil)
+	return target
+}
+
+func (s *Server) deletePostImageObjects(keys []string) {
+	if len(keys) == 0 {
+		return
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), postImageCleanupTimeout)
+	defer cancel()
+	for _, key := range keys {
+		if err := s.cfg.Blob.Delete(ctx, key); err != nil {
+			log.Printf("delete post image %s: %v", key, err)
+		}
+	}
+}
+
+func removedPostImageKeys(before, after []store.PostImage) []string {
+	retained := make(map[string]bool, len(after))
+	for _, image := range after {
+		retained[image.ObjectKey] = true
+	}
+	var removed []string
+	for _, image := range before {
+		if !retained[image.ObjectKey] {
+			removed = append(removed, image.ObjectKey)
+		}
+	}
+	return removed
+}

internal/web/post_images_test.go

@@ -0,0 +1,443 @@
+package web
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"image"
+	"image/color"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"mime/multipart"
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"testing"
+
+	"plumber/internal/blob"
+	"plumber/internal/pacific"
+	"plumber/internal/store"
+)
+
+func TestPreparePostImage(t *testing.T) {
+	t.Parallel()
+
+	wide := solidPNG(t, 2000, 1000)
+	prepared, err := preparePostImageHeader(t, "wide.png", wide)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if prepared.width != 1600 || prepared.height != 800 ||
+		prepared.extension != ".png" || prepared.contentType != "image/png" {
+		t.Fatalf("prepared PNG = %+v", prepared)
+	}
+
+	jpegBody := solidJPEG(t, 40, 20)
+	prepared, err = preparePostImageHeader(t, "photo.jpg", jpegBody)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if prepared.width != 40 || prepared.height != 20 ||
+		prepared.extension != ".jpg" || prepared.contentType != "image/jpeg" {
+		t.Fatalf("prepared JPEG = %+v", prepared)
+	}
+
+	if _, err := preparePostImageHeader(t, "notes.txt", []byte("not an image")); err == nil {
+		t.Fatal("text upload unexpectedly succeeded")
+	}
+	_, err = preparePostImageHeader(t, "too-large.jpg", make([]byte, postImageMaxFileBytes+1))
+	var requestErr *postImageRequestError
+	if !errors.As(err, &requestErr) || requestErr.status != http.StatusRequestEntityTooLarge {
+		t.Fatalf("oversized file error = %v, want 413 request error", err)
+	}
+	if _, err := preparePostImageHeader(t, "too-wide.png", solidPNG(t, 6001, 1)); err == nil {
+		t.Fatal("oversized dimensions unexpectedly succeeded")
+	}
+}
+
+func TestOrientPostImage(t *testing.T) {
+	t.Parallel()
+
+	source := image.NewNRGBA(image.Rect(0, 0, 2, 1))
+	source.Set(0, 0, color.NRGBA{R: 255, A: 255})
+	source.Set(1, 0, color.NRGBA{B: 255, A: 255})
+	rotated := orientPostImage(source, 6)
+	if rotated.Bounds().Dx() != 1 || rotated.Bounds().Dy() != 2 {
+		t.Fatalf("rotated bounds = %v", rotated.Bounds())
+	}
+	top := color.NRGBAModel.Convert(rotated.At(0, 0)).(color.NRGBA)
+	bottom := color.NRGBAModel.Convert(rotated.At(0, 1)).(color.NRGBA)
+	if top.R != 255 || bottom.B != 255 {
+		t.Fatalf("rotation colors top=%v bottom=%v", top, bottom)
+	}
+}
+
+func TestPostImageMultipartLifecycle(t *testing.T) {
+	t.Parallel()
+
+	images := &recordingImageBlob{}
+	srv, mem := newTestServer(t, Config{Blob: images})
+	handler := srv.Handler()
+	homeowner := seedUser(t, mem, uniq("images"), "hunter22", store.RoleUser)
+	cookies := loginUser(t, handler, homeowner.Username, "hunter22")
+	csrf := csrfForCookies(t, handler, cookies)
+
+	rec := multipartPost(t, handler, "/submit", map[string][]string{
+		"_csrf":             {csrf},
+		"title":             {"Leaky valve"},
+		"body":              {"Two views of the leak."},
+		"city":              {"Oakland"},
+		"image_description": {"Front view", "Under the sink"},
+	}, []multipartTestFile{
+		{name: "front.png", body: solidPNG(t, 80, 40)},
+		{name: "under.jpg", body: solidJPEG(t, 40, 80)},
+	}, cookies)
+	if rec.Code != http.StatusSeeOther {
+		t.Fatalf("root image upload status = %d: %s", rec.Code, rec.Body.String())
+	}
+	roots, err := mem.ListRootPosts(context.Background(), pacific.Today(), homeowner.ID)
+	if err != nil || len(roots) != 1 {
+		t.Fatalf("roots = %+v, %v", roots, err)
+	}
+	root, err := mem.GetPost(context.Background(), roots[0].ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(root.Images) != 2 ||
+		root.Images[0].Description != "Front view" ||
+		root.Images[1].Description != "Under the sink" {
+		t.Fatalf("root images = %+v", root.Images)
+	}
+
+	rec = multipartPost(t, handler, "/posts", map[string][]string{
+		"_csrf":             {csrf},
+		"parent_id":         {root.ID},
+		"body":              {"Here is the model label."},
+		"image_description": {"Model label"},
+	}, []multipartTestFile{{name: "label.png", body: solidPNG(t, 60, 30)}}, cookies)
+	if rec.Code != http.StatusSeeOther {
+		t.Fatalf("reply image upload status = %d: %s", rec.Code, rec.Body.String())
+	}
+	thread, err := mem.GetPostThread(context.Background(), root.ID)
+	if err != nil || len(thread.Replies) != 1 {
+		t.Fatalf("thread = %+v, %v", thread, err)
+	}
+	reply := thread.Replies[0]
+	if len(reply.Images) != 1 || reply.Images[0].Description != "Model label" {
+		t.Fatalf("reply images = %+v", reply.Images)
+	}
+	originalKey := reply.Images[0].ObjectKey
+
+	rec = multipartPost(t, handler, "/posts/"+reply.ID+"/edit", map[string][]string{
+		"_csrf":                      {csrf},
+		"body":                       {"Updated label photos."},
+		"existing_image_id":          {reply.Images[0].ID},
+		"existing_image_description": {"Existing label"},
+		"image_description":          {"Serial number"},
+	}, []multipartTestFile{{name: "serial.jpg", body: solidJPEG(t, 50, 25)}}, cookies)
+	if rec.Code != http.StatusSeeOther {
+		t.Fatalf("image edit status = %d: %s", rec.Code, rec.Body.String())
+	}
+	edited, err := mem.GetPost(context.Background(), reply.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(edited.Images) != 2 ||
+		edited.Images[0].Description != "Existing label" ||
+		edited.Images[1].Description != "Serial number" {
+		t.Fatalf("edited images = %+v", edited.Images)
+	}
+
+	rec = multipartPost(t, handler, "/posts/"+reply.ID+"/edit", map[string][]string{
+		"_csrf":                      {csrf},
+		"body":                       {"Keep only the serial number."},
+		"existing_image_id":          {edited.Images[1].ID},
+		"existing_image_description": {"Serial number"},
+	}, nil, cookies)
+	if rec.Code != http.StatusSeeOther {
+		t.Fatalf("image removal status = %d: %s", rec.Code, rec.Body.String())
+	}
+	edited, err = mem.GetPost(context.Background(), reply.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(edited.Images) != 1 || edited.Images[0].Description != "Serial number" {
+		t.Fatalf("images after removal = %+v", edited.Images)
+	}
+	if !images.wasDeleted(originalKey) {
+		t.Fatalf("removed object %q was not deleted: %+v", originalKey, images.deletedKeys())
+	}
+
+	uploadsBefore := images.uploadCount()
+	rec = multipartPost(t, handler, "/posts/"+reply.ID+"/edit", map[string][]string{
+		"_csrf":             {csrf},
+		"body":              {"Invalid retained image."},
+		"existing_image_id": {"not-owned"},
+	}, nil, cookies)
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("invalid retained image status = %d, want 400", rec.Code)
+	}
+	unchanged, err := mem.GetPost(context.Background(), reply.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if unchanged.Body != "Keep only the serial number." || len(unchanged.Images) != 1 {
+		t.Fatalf("invalid retained image changed post: %+v", unchanged)
+	}
+
+	files := make([]multipartTestFile, store.MaxPostImages+1)
+	for i := range files {
+		files[i] = multipartTestFile{name: "extra.png", body: solidPNG(t, 10, 10)}
+	}
+	rec = multipartPost(t, handler, "/posts", map[string][]string{
+		"_csrf":     {csrf},
+		"parent_id": {root.ID},
+		"body":      {"Too many images."},
+	}, files, cookies)
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("five-image status = %d, want 400", rec.Code)
+	}
+	if images.uploadCount() != uploadsBefore {
+		t.Fatal("five-image request uploaded objects before rejecting count")
+	}
+}
+
+func TestPostImageUploadCompensation(t *testing.T) {
+	t.Parallel()
+
+	t.Run("blob failure deletes earlier upload", func(t *testing.T) {
+		images := &recordingImageBlob{failAt: 2}
+		srv, mem := newTestServer(t, Config{Blob: images})
+		handler := srv.Handler()
+		user := seedUser(t, mem, uniq("blob-fail"), "hunter22", store.RoleUser)
+		cookies := loginUser(t, handler, user.Username, "hunter22")
+		csrf := csrfForCookies(t, handler, cookies)
+		rec := multipartPost(t, handler, "/submit", map[string][]string{
+			"_csrf": {csrf},
+			"title": {"Upload failure"},
+			"body":  {"Should not persist."},
+		}, []multipartTestFile{
+			{name: "one.png", body: solidPNG(t, 10, 10)},
+			{name: "two.png", body: solidPNG(t, 10, 10)},
+		}, cookies)
+		if rec.Code != http.StatusServiceUnavailable {
+			t.Fatalf("blob failure status = %d: %s", rec.Code, rec.Body.String())
+		}
+		if images.uploadCount() != 1 || len(images.deletedKeys()) != 1 {
+			t.Fatalf("blob compensation uploads=%d deletes=%v", images.uploadCount(), images.deletedKeys())
+		}
+	})
+
+	t.Run("store failure deletes uploaded object", func(t *testing.T) {
+		images := &recordingImageBlob{}
+		mem := store.NewMemory()
+		failing := &failingCreatePostStore{Store: mem}
+		srv := newTestServerStore(t, failing, Config{Blob: images})
+		handler := srv.Handler()
+		user := seedUser(t, mem, uniq("store-fail"), "hunter22", store.RoleUser)
+		cookies := loginUser(t, handler, user.Username, "hunter22")
+		csrf := csrfForCookies(t, handler, cookies)
+		rec := multipartPost(t, handler, "/submit", map[string][]string{
+			"_csrf": {csrf},
+			"title": {"Store failure"},
+			"body":  {"Should clean up."},
+		}, []multipartTestFile{{name: "one.png", body: solidPNG(t, 10, 10)}}, cookies)
+		if rec.Code != http.StatusInternalServerError {
+			t.Fatalf("store failure status = %d: %s", rec.Code, rec.Body.String())
+		}
+		if images.uploadCount() != 1 || len(images.deletedKeys()) != 1 {
+			t.Fatalf("store compensation uploads=%d deletes=%v", images.uploadCount(), images.deletedKeys())
+		}
+	})
+}
+
+func TestPostImageRequestLimits(t *testing.T) {
+	t.Parallel()
+
+	for _, test := range []struct {
+		method string
+		path   string
+		want   int64
+	}{
+		{http.MethodPost, "/submit", postImageMaxRequestBytes},
+		{http.MethodPost, "/posts", postImageMaxRequestBytes},
+		{http.MethodPost, "/posts/id/edit", postImageMaxRequestBytes},
+		{http.MethodPost, "/login", defaultRequestBodyBytes},
+		{http.MethodGet, "/posts", defaultRequestBodyBytes},
+	} {
+		req := httptest.NewRequest(test.method, test.path, nil)
+		if got := requestBodyLimit(req); got != test.want {
+			t.Errorf("%s %s limit = %d, want %d", test.method, test.path, got, test.want)
+		}
+	}
+}
+
+type multipartTestFile struct {
+	name string
+	body []byte
+}
+
+func multipartPost(
+	t *testing.T,
+	handler http.Handler,
+	requestPath string,
+	fields map[string][]string,
+	files []multipartTestFile,
+	cookies []*http.Cookie,
+) *httptest.ResponseRecorder {
+	t.Helper()
+	var body bytes.Buffer
+	writer := multipart.NewWriter(&body)
+	for name, values := range fields {
+		for _, value := range values {
+			if err := writer.WriteField(name, value); err != nil {
+				t.Fatal(err)
+			}
+		}
+	}
+	for _, file := range files {
+		part, err := writer.CreateFormFile("images", file.name)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if _, err := part.Write(file.body); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := writer.Close(); err != nil {
+		t.Fatal(err)
+	}
+	req := httptest.NewRequest(http.MethodPost, requestPath, &body)
+	req.Header.Set("Content-Type", writer.FormDataContentType())
+	for _, cookie := range cookies {
+		req.AddCookie(cookie)
+	}
+	rec := httptest.NewRecorder()
+	handler.ServeHTTP(rec, req)
+	return rec
+}
+
+func preparePostImageHeader(t *testing.T, name string, body []byte) (preparedPostImage, error) {
+	t.Helper()
+	var requestBody bytes.Buffer
+	writer := multipart.NewWriter(&requestBody)
+	part, err := writer.CreateFormFile("images", name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := part.Write(body); err != nil {
+		t.Fatal(err)
+	}
+	if err := writer.Close(); err != nil {
+		t.Fatal(err)
+	}
+	req := httptest.NewRequest(http.MethodPost, "/posts", &requestBody)
+	req.Header.Set("Content-Type", writer.FormDataContentType())
+	if err := req.ParseMultipartForm(postImageMultipartMemory); err != nil {
+		t.Fatal(err)
+	}
+	defer req.MultipartForm.RemoveAll()
+	return preparePostImage(req.MultipartForm.File["images"][0])
+}
+
+func solidPNG(t *testing.T, width, height int) []byte {
+	t.Helper()
+	img := image.NewNRGBA(image.Rect(0, 0, width, height))
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			img.Set(x, y, color.NRGBA{R: 30, G: 90, B: 140, A: 255})
+		}
+	}
+	var out bytes.Buffer
+	if err := png.Encode(&out, img); err != nil {
+		t.Fatal(err)
+	}
+	return out.Bytes()
+}
+
+func solidJPEG(t *testing.T, width, height int) []byte {
+	t.Helper()
+	img := image.NewNRGBA(image.Rect(0, 0, width, height))
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			img.Set(x, y, color.NRGBA{R: 140, G: 90, B: 30, A: 255})
+		}
+	}
+	var out bytes.Buffer
+	if err := jpeg.Encode(&out, img, &jpeg.Options{Quality: 90}); err != nil {
+		t.Fatal(err)
+	}
+	return out.Bytes()
+}
+
+type recordedImageUpload struct {
+	key         string
+	contentType string
+	body        []byte
+}
+
+type recordingImageBlob struct {
+	mu      sync.Mutex
+	calls   int
+	failAt  int
+	uploads []recordedImageUpload
+	deletes []string
+}
+
+func (b *recordingImageBlob) Enabled() bool { return true }
+
+func (b *recordingImageBlob) Upload(_ context.Context, object blob.FileUpload) (string, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	b.calls++
+	if b.failAt > 0 && b.calls == b.failAt {
+		return "", errors.New("injected upload failure")
+	}
+	body, err := io.ReadAll(object.Body)
+	if err != nil {
+		return "", err
+	}
+	b.uploads = append(b.uploads, recordedImageUpload{
+		key:         object.Key,
+		contentType: object.ContentType,
+		body:        body,
+	})
+	return "https://cdn.example/" + object.Key, nil
+}
+
+func (b *recordingImageBlob) Delete(_ context.Context, key string) error {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	b.deletes = append(b.deletes, key)
+	return nil
+}
+
+func (b *recordingImageBlob) uploadCount() int {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return len(b.uploads)
+}
+
+func (b *recordingImageBlob) deletedKeys() []string {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return append([]string(nil), b.deletes...)
+}
+
+func (b *recordingImageBlob) wasDeleted(key string) bool {
+	for _, deleted := range b.deletedKeys() {
+		if deleted == key {
+			return true
+		}
+	}
+	return false
+}
+
+type failingCreatePostStore struct {
+	store.Store
+}
+
+func (f *failingCreatePostStore) CreatePost(context.Context, *store.Post) error {
+	return errors.New("injected store failure")
+}

internal/web/posts.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
+	"github.com/google/uuid"
 
 	"plumber/internal/mail"
 	"plumber/internal/store"
@@ -20,6 +21,11 @@ import (
 // handleCreatePost creates either a root question or a reply. Replies are
 // limited to the root author and admins, and cannot be added to hidden threads.
 func (s *Server) handleCreatePost(w http.ResponseWriter, r *http.Request) {
+	cleanup, ok := parsePostMutationForm(w, r)
+	if !ok {
+		return
+	}
+	defer cleanup()
 	if !s.requireCSRF(w, r) {
 		return
 	}
@@ -37,6 +43,7 @@ func (s *Server) handleCreatePost(w http.ResponseWriter, r *http.Request) {
 	}
 
 	post := &store.Post{
+		ID:       uuid.NewString(),
 		AuthorID: user.ID,
 		Body:     truncateRunes(body, 12000),
 	}
@@ -71,7 +78,14 @@ func (s *Server) handleCreatePost(w http.ResponseWriter, r *http.Request) {
 		root = threadRoot
 	}
 
+	images, newKeys, err := s.postImagesFromForm(r.Context(), r, post.ID, nil)
+	if err != nil {
+		writePostImageRequestError(w, err)
+		return
+	}
+	post.Images = images
 	if err := s.store.CreatePost(r.Context(), post); err != nil {
+		s.deletePostImageObjects(newKeys)
 		if errors.Is(err, store.ErrInvalidPost) {
 			http.Error(w, "invalid post", http.StatusBadRequest)
 			return
@@ -85,7 +99,6 @@ func (s *Server) handleCreatePost(w http.ResponseWriter, r *http.Request) {
 	if parent != nil {
 		s.notifyPostReply(parent, root, post, user)
 	}
-	s.publishPostCreated(post, root, user)
 	http.Redirect(
 		w,
 		r,
@@ -150,6 +163,11 @@ func (s *Server) notifyPostReply(
 // handleEditPost updates only a post's body after verifying that the current
 // homeowner owns it or that an admin is editing an admin-authored post.
 func (s *Server) handleEditPost(w http.ResponseWriter, r *http.Request) {
+	cleanup, ok := parsePostMutationForm(w, r)
+	if !ok {
+		return
+	}
+	defer cleanup()
 	if !s.requireCSRF(w, r) {
 		return
 	}
@@ -178,8 +196,16 @@ func (s *Server) handleEditPost(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "post body required", http.StatusBadRequest)
 		return
 	}
+	previousImages := append([]store.PostImage(nil), post.Images...)
+	images, newKeys, err := s.postImagesFromForm(r.Context(), r, post.ID, previousImages)
+	if err != nil {
+		writePostImageRequestError(w, err)
+		return
+	}
 	post.Body = truncateRunes(body, 12000)
+	post.Images = images
 	if err := s.store.UpdatePost(r.Context(), post); err != nil {
+		s.deletePostImageObjects(newKeys)
 		if errors.Is(err, store.ErrInvalidPost) {
 			http.Error(w, "invalid post", http.StatusBadRequest)
 			return
@@ -191,7 +217,7 @@ func (s *Server) handleEditPost(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "could not save post", http.StatusInternalServerError)
 		return
 	}
-	s.publishPostUpdated(post, root, nil)
+	s.deletePostImageObjects(removedPostImageKeys(previousImages, images))
 	http.Redirect(
 		w,
 		r,

internal/web/server.go

@@ -18,9 +18,9 @@ import (
 	"github.com/alexedwards/scs/v2"
 	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
+	"github.com/google/uuid"
 
 	"plumber/internal/blob"
-	"plumber/internal/events"
 	"plumber/internal/geo"
 	"plumber/internal/mail"
 	"plumber/internal/pacific"
@@ -36,8 +36,6 @@ type Config struct {
 	TrustedProxies []*net.IPNet
 	Blob           blob.Uploader
 	Mail           mail.Notifier
-	Events         events.Publisher
-	BaseURL        string
 }
 
 type Server struct {
@@ -113,9 +111,6 @@ func New(st store.Store, sessionStore scs.Store, templateFS fs.FS, staticFS fs.F
 	if cfg.Mail == nil {
 		cfg.Mail = mail.Nop{}
 	}
-	if cfg.Events == nil {
-		cfg.Events = events.Nop{}
-	}
 	funcMap := template.FuncMap{
 		"voteCtx": func(user *store.User, csrf, view, date string, post *store.Post) voteCtx {
 			return voteCtx{User: user, CSRF: csrf, View: view, Date: date, Post: post}
@@ -188,7 +183,7 @@ func (s *Server) Handler() http.Handler {
 	r.Use(middleware.Recoverer)
 	r.Use(func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			r.Body = http.MaxBytesReader(w, r.Body, 3<<20)
+			r.Body = http.MaxBytesReader(w, r.Body, requestBodyLimit(r))
 			next.ServeHTTP(w, r)
 		})
 	})
@@ -337,6 +332,11 @@ func (s *Server) handleSubmitForm(w http.ResponseWriter, r *http.Request) {
 }
 
 func (s *Server) handleSubmit(w http.ResponseWriter, r *http.Request) {
+	cleanup, ok := parsePostMutationForm(w, r)
+	if !ok {
+		return
+	}
+	defer cleanup()
 	if !s.requireCSRF(w, r) {
 		return
 	}
@@ -368,16 +368,23 @@ func (s *Server) handleSubmit(w http.ResponseWriter, r *http.Request) {
 		city = truncateRunes(city, 80)
 	}
 	post := &store.Post{
+		ID:       uuid.NewString(),
 		AuthorID: u.ID,
 		Title:    title,
 		Body:     body,
 		City:     city,
 	}
+	images, newKeys, err := s.postImagesFromForm(r.Context(), r, post.ID, nil)
+	if err != nil {
+		writePostImageRequestError(w, err)
+		return
+	}
+	post.Images = images
 	if err := s.store.CreatePost(r.Context(), post); err != nil {
+		s.deletePostImageObjects(newKeys)
 		http.Error(w, "could not save question", http.StatusInternalServerError)
 		return
 	}
-	s.publishPostCreated(post, post, u)
 	http.Redirect(w, r, "/questions/"+url.PathEscape(post.ID), http.StatusSeeOther)
 }