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Educational demo of a single node, sqlite, Datastar, CQRS app with low latency UX.
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main
import ( "bytes" "context" "database/sql" "encoding/json" "errors" "flag" "fmt" "hash/fnv" "html/template" "io" "io/fs" "log" "mime" "net/http" "os" "os/signal" "runtime" "slices" "strconv" "strings" "sync/atomic" "syscall" "time" "unicode/utf8"
"github.com/starfederation/datastar-go/datastar" "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp" "go.opentelemetry.io/otel/attribute" "golang.org/x/crypto/acme/autocert")
type app struct { reads *store // concurrent read pool (WAL) + prepared hot-path statements writer *Writer // single serialized write path counts *CountCache // shared, version-invalidated count cache lists *ListCache // shared, version-invalidated rendered-list cache hub *Hub traces *traceHub // sanitized realtime trace view feed; nil unless -trace-view catalog []Label authors atomic.Pointer[[]string] // distinct issue authors for the filter datalist; copy-on-write (see addAuthor) stats *appStats writeLimit bool // write rate-limit toggle (disable for load tests) writes *writeLimiter // per-identity write budget (keyed by login, not sid) brWin int // brotli lgwin (sliding window) for the stream brQ int // brotli quality (0-11) compress bool // compress the SSE stream (kill-switch: -compress=false serves uncompressed to everyone) maxConns int // cap on concurrent SSE streams (503 over it; 0 = unlimited) auth *Auth devUser string // local-dev write identity when auth is off ("" = browse-only) baseURL string // public origin (scheme://host[:port]); used for the CSRF Origin check shutdown chan struct{} // closed on srv.Shutdown so SSE streams exit promptly (Shutdown doesn't cancel request contexts)}
const cookieName = "dbugs_sid"
// tabCookieName is the seconds-lived reload-restore cookie: beforeunload stamps// the per-tab sid into it (see index.html) so the very next same-tab navigation// can SSR that tab's real session. Without it a reload paints the DEFAULT// projection and the stream's first push visibly converges the whole UI.// Short Max-Age + expire-on-use keep it from leaking one tab's view into// another tab opened later.const tabCookieName = "dbugs_tab"
func main() { addr := flag.String("addr", ":8080", "listen address") dsn := flag.String("db", "file:dbugs.db", "sqlite dsn") seedN := flag.Int("seed", 10000, "number of fake issues to seed (0 = skip seeding existing db)") fresh := flag.Bool("fresh", true, "drop & reseed a throwaway temp-file DB on start") writeLimit := flag.Bool("writelimit", true, "per-identity write rate limit (set false for load tests)") frame := flag.Duration("frame", 16*time.Millisecond, "fan-out batching window (push at most once per frame per session)") sessionTTL := flag.Duration("session-ttl", 5*time.Minute, "evict sessions with no live streams after this idle period") brWin := flag.Int("brwin", 16, "brotli sliding-window lgwin (10-24); 16=64KB covers our ~40KB fragments") brQ := flag.Int("brq", 4, "brotli quality (0-11); lower = less per-conn memory + CPU (q2≈0.7MB/conn, q0≈0.37MB)") compress := flag.Bool("compress", true, "compress the SSE stream; -compress=false serves uncompressed to all (debug/fallback)") adminAddr := flag.String("admin-addr", "127.0.0.1:8081", "debug/admin listener; keep local/tailnet-only, never public") maxConns := flag.Int("max-conns", 4000, "max concurrent SSE streams before 503 (0 = unlimited)") tlsDomain := flag.String("tls-domain", "", "autocert domain (e.g. dbugs.yagni.club); empty = plain HTTP on -addr") tlsAddr := flag.String("tls-addr", ":443", "HTTPS listen address when -tls-domain is set") tlsCache := flag.String("tls-cache", "certs", "directory to cache Let's Encrypt certificates") baseURL := flag.String("base-url", "", "public base URL for OAuth redirects (default: from -tls-domain or -addr)") authKeyFile := flag.String("auth-key-file", "auth_key", "file holding the cookie signing key (auto-generated)") devUser := flag.String("dev-user", "", "local-dev write identity when auth is disabled (empty = browse-only)") traceView := flag.Bool("trace-view", true, "serve the sanitized, public realtime trace view at GET /traces (educational/transparency; -trace-view=false to disable)") scopedInval := flag.Bool("scoped-inval", true, "predicate-scoped cache invalidation: writes stale only the list/count keys they could affect (=false: every write stales every key)") flag.Parse()
// Startup context for seeding/migrations: they run to completion on the main // goroutine before the server starts, so there is no cancellation to wire up. ctx := context.Background()
// Public trace view: a sanitized, realtime span feed at /traces, ON by // default — it exists for education/transparency, and the deny-by-default // attribute allow-list (trace.go) is what makes it safe to expose, not a // gate. -trace-view=false opts out. The hub's sink sees every span on End; // passing it to setupTracing turns tracing on for the view alone, so it // works with no collector and no stdout spam (otel.go). Frame batching // matches the issue hub's. var traces *traceHub if *traceView { traces = newTraceHub(*frame) }
// Tracing before anything else, so every subsystem below can emit spans. // No-op unless an OTLP endpoint is configured or the trace view is on. otelShutdown, otelOn, err := setupTracing(ctx, traces) if err != nil { log.Fatalf("otel: %v", err) } log.Printf("otel: tracing enabled=%v trace-view=%v", otelOn, *traceView)
baseDSN := *dsn if *fresh { // A real temp file, not mode=memory: see freshDSN for why (in-memory // shared-cache has no WAL, so readers would block behind writes). freshDB, cleanup, err := freshDSN() if err != nil { log.Fatal(err) } defer cleanup() baseDSN = freshDB }
// Single-writer connection: all mutations serialize through this, so they // never contend for the SQLite write lock. writeDB, err := sql.Open("sqlite", withPragmas(baseDSN)) if err != nil { log.Fatal(err) } writeDB.SetMaxOpenConns(1) writeDB.SetConnMaxIdleTime(0) defer writeDB.Close()
// Seed / migrate on the writer connection. if *fresh { log.Printf("seeding %d fake issues into fresh temp sqlite at %s…", *seedN, baseDSN) if err := SeedDB(ctx, writeDB, *seedN); err != nil { log.Fatalf("seed: %v", err) } } else if !tableExists(ctx, writeDB, "issues") { log.Printf("empty db: seeding %d fake issues into %s…", *seedN, baseDSN) if err := SeedDB(ctx, writeDB, *seedN); err != nil { log.Fatalf("seed: %v", err) } } else { log.Printf("using existing db %s (skipping seed)", baseDSN) } t0 := time.Now() for _, mig := range []struct { name string fn func(context.Context, *sql.DB) error }{ // guest-columns first: EnsureIndexes builds an index on creator_name, which // this migration adds. (On an existing DB the column is already present; on // a fresh seed — the default — it isn't yet, so order matters.) {"guest-columns", EnsureGuestColumns}, {"indexes", EnsureIndexes}, {"fts", EnsureFTS}, } { if err := mig.fn(ctx, writeDB); err != nil { log.Fatalf("migrate %s: %v", mig.name, err) } } log.Printf("migrations ready in %v", time.Since(t0).Round(time.Millisecond)) // Refresh planner stats so it picks the right index (e.g. the author // composites) — cheap after the first run; only re-analyzes on big changes. if _, err := writeDB.ExecContext(ctx, `PRAGMA optimize`); err != nil { log.Printf("pragma optimize: %v", err) }
// Read pool: WAL allows many readers concurrently with the writer. readDB, err := sql.Open("sqlite", withPragmas(baseDSN)) if err != nil { log.Fatal(err) } // More read conns than cores so detail/list reads overlap (one waiting on a // cold page or WAL frame doesn't stall others) under fan-out. Each adds ~16 MB // page cache, so cap it. WAL allows the concurrency; cores bound actual CPU. readers := runtime.NumCPU() * 2 if readers < 8 { readers = 8 } if readers > 32 { readers = 32 } readDB.SetMaxOpenConns(readers) readDB.SetMaxIdleConns(readers) defer readDB.Close()
// Wrap the pool in the read store, preparing the hot fixed-shape queries // once (GetIssue + author lookup). reads, err := newStore(ctx, readDB) if err != nil { log.Fatal(err) }
catalog, err := AllLabels(ctx, readDB) if err != nil { log.Fatal(err) } authors, err := AllAuthors(ctx, readDB) if err != nil { log.Fatal(err) }
hub := newHub(*frame, *sessionTTL) var version atomic.Uint64 // Caches before the writer: scoped invalidation (inval.go) has the writer // walk them by predicate after each commit. -scoped-inval=false detaches // them, reverting to the global version-bump fallback (for A/B measurement). counts := newCountCache(reads, &version) lists := newListCache(reads, &version) writerLists, writerCounts := lists, counts if !*scopedInval { writerLists, writerCounts = nil, nil } writer := newWriter(writeDB, hub, &version, writerLists, writerCounts) go writer.run()
// Auth: GitHub OAuth, gating writes. Disabled (open/guest mode) unless a // client id + secret are present, so local dev needs no setup. base := *baseURL if base == "" { if *tlsDomain != "" { base = "https://" + *tlsDomain } else { base = "http://localhost" + *addr } } auth, err := newAuth(base, *authKeyFile) if err != nil { log.Fatal(err) } log.Printf("auth: enabled=%v base=%s", auth.enabled, base)
a := &app{ reads: reads, writer: writer, counts: counts, lists: lists, hub: hub, traces: traces, catalog: catalog, stats: &appStats{}, writeLimit: *writeLimit, writes: newWriteLimiter(), brWin: *brWin, brQ: *brQ, compress: *compress, maxConns: *maxConns, auth: auth, devUser: *devUser, baseURL: strings.TrimRight(base, "/"), shutdown: make(chan struct{}), } a.authors.Store(&authors) go a.sample()
// ---- public listener: the app, stream, and commands ---- pub := http.NewServeMux() staticSub, err := fs.Sub(staticFS, "static") if err != nil { log.Fatal(err) } // Go's built-in mime table lacks woff2; register it so the embedded fonts are // served as font/woff2 rather than sniffed to application/octet-stream. _ = mime.AddExtensionType(".woff2", "font/woff2") staticFile := http.StripPrefix("/static/", http.FileServer(http.FS(staticSub))) pub.Handle("GET /static/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { // Embedded, self-hosted assets (incl. datastar.js — no CDN, no SRI gap). // 1h cache keeps deploys fresh-ish; a redeploy changes the bytes. w.Header().Set("Cache-Control", "public, max-age=3600") staticFile.ServeHTTP(w, r) })) pub.HandleFunc("GET /", a.handleIndex) pub.HandleFunc("GET /i/{id}", a.handleIssue) // canonical shareable issue permalink pub.HandleFunc("GET /stream", a.handleStream)
// Public trace view: SSR page + its own long-lived morph stream, mounted // by default (-trace-view=false unmounts it). /traces/stream is excluded // from HTTP tracing below (like /stream) — and crucially the trace push // path is uninstrumented, so a push can't mint a span that wakes viewers // into another push (a feedback loop). if a.traces != nil { pub.HandleFunc("GET /traces", a.handleTraces) pub.HandleFunc("GET /traces/stream", a.handleTraceStream) log.Printf("trace view: serving GET /traces (sanitized, read-only)") }
// GitHub OAuth (full-page redirects, not Datastar commands). pub.HandleFunc("GET /auth/github/login", a.auth.login) pub.HandleFunc("GET /auth/github/callback", a.auth.callback) // Logout mutates state, so it's a POST (a plain form in the template) and // withSecurity extends the same-origin check to it — a cross-site GET/link // can't force a sign-out. pub.HandleFunc("POST /auth/logout", a.auth.logout)
// Read commands. // Result-set-changing commands reset the list scroll to the top. pub.HandleFunc("POST /cmd/search", a.cmdScrollTop(a.doSearch)) pub.HandleFunc("POST /cmd/status", a.cmdScrollTop(a.doStatus)) pub.HandleFunc("POST /cmd/toggle-label", a.cmdScrollTop(a.doToggleLabel)) pub.HandleFunc("POST /cmd/clear-labels", a.cmdScrollTop(a.doClearLabels)) pub.HandleFunc("POST /cmd/author", a.cmdScrollTop(a.doAuthor)) pub.HandleFunc("POST /cmd/clear-author", a.cmdScrollTop(a.doClearAuthor)) pub.HandleFunc("POST /cmd/author-me", a.cmdScrollTop(a.doAuthorMe)) pub.HandleFunc("POST /cmd/sort", a.cmdScrollTop(a.doSort)) pub.HandleFunc("POST /cmd/sortdir", a.cmdScrollTop(a.doSortDir)) pub.HandleFunc("POST /cmd/more", a.cmd(a.doMore)) pub.HandleFunc("POST /cmd/select", a.cmd(a.doSelect)) pub.HandleFunc("POST /cmd/close", a.cmd(a.doClose)) pub.HandleFunc("POST /cmd/compose", a.cmd(a.doCompose)) pub.HandleFunc("POST /cmd/compose-cancel", a.cmd(a.doComposeCancel)) pub.HandleFunc("POST /cmd/edit-start", a.handleEditStart) pub.HandleFunc("POST /cmd/edit-cancel", a.cmd(a.doEditCancel)) pub.HandleFunc("POST /cmd/stats", a.cmd(a.doStats))
// Command system: keyboard dispatch + the ⌘K palette (see command.go). /cmd/key // resolves a key combo server-side; palette-query/nav drive the open palette // and deliberately keep it open (cmdKeep). pub.HandleFunc("POST /cmd/key", a.handleKey) pub.HandleFunc("POST /cmd/palette-query", a.cmdKeep(a.doPaletteQuery)) pub.HandleFunc("POST /cmd/palette-nav", a.cmdKeep(a.doPaletteNav))
// Write commands. pub.HandleFunc("POST /cmd/comment", a.handleComment) pub.HandleFunc("POST /cmd/create", a.handleCreate) pub.HandleFunc("POST /cmd/edit", a.handleEditSave)
// (The 📊 debug panel rides the main projection pipe via /cmd/stats — no // dedicated stats connection.)
// ---- admin listener: profiling endpoints, bound to -admin-addr (localhost // by default) so they're never publicly reachable. /debug/gc is a // stop-the-world DoS if exposed; reach these via the tailnet after SSH'ing in. admin := http.NewServeMux() admin.HandleFunc("GET /debug/cache", func(w http.ResponseWriter, r *http.Request) { h, m := a.lists.hits.Load(), a.lists.misses.Load() total := h + m var rate float64 if total > 0 { rate = 100 * float64(h) / float64(total) } fmt.Fprintf(w, "list cache: hits=%d misses=%d (%.1f%% hit)\n", h, m, rate) }) admin.HandleFunc("GET /debug/gc", func(w http.ResponseWriter, r *http.Request) { runtime.GC() var m runtime.MemStats runtime.ReadMemStats(&m) mb := func(b uint64) float64 { return float64(b) / (1 << 20) } fmt.Fprintf(w, "streams=%d goroutines=%d HeapInuse=%.0fMB HeapAlloc=%.0fMB Sys=%.0fMB\n", a.stats.streams.Load(), runtime.NumGoroutine(), mb(m.HeapInuse), mb(m.HeapAlloc), mb(m.Sys)) }) go func() { log.Printf("admin/debug on http://%s (local only)", *adminAddr) adminSrv := &http.Server{Addr: *adminAddr, Handler: admin, ReadHeaderTimeout: 10 * time.Second} if err := adminSrv.ListenAndServe(); err != nil { log.Printf("admin listener: %v", err) } }()
// ---- serve the public mux: HTTPS via autocert if a domain is set ---- // WriteTimeout is deliberately omitted: it would kill the long-lived SSE // streams. IdleTimeout only bounds keep-alive connections between requests, // so it's safe alongside SSE. handler := a.withSecurity(pub) if otelOn { // Free per-request spans for every page load and command POST. The // long-lived /stream would be one giant span, so it's filtered out here — // its work is traced per push instead (sse.push in pushProjection). // Static assets are skipped as noise. handler = otelhttp.NewHandler(handler, "http", otelhttp.WithFilter(func(r *http.Request) bool { return r.URL.Path != "/stream" && r.URL.Path != "/traces/stream" && !strings.HasPrefix(r.URL.Path, "/static/") }), otelhttp.WithSpanNameFormatter(func(_ string, r *http.Request) string { p := r.URL.Path if strings.HasPrefix(p, "/i/") { p = "/i/{id}" // bound span-name cardinality } return r.Method + " " + p }), ) } srv := &http.Server{ Handler: handler, ReadHeaderTimeout: 10 * time.Second, IdleTimeout: 120 * time.Second, } srv.RegisterOnShutdown(func() { close(a.shutdown) }) serveErr := make(chan error, 1) if *tlsDomain != "" { mgr := &autocert.Manager{ Cache: autocert.DirCache(*tlsCache), Prompt: autocert.AcceptTOS, HostPolicy: autocert.HostWhitelist(*tlsDomain), } srv.Addr = *tlsAddr srv.TLSConfig = mgr.TLSConfig() // TLS-ALPN-01 on 443 — no port 80 needed log.Printf("serving https://%s on %s (admin on %s)", *tlsDomain, *tlsAddr, *adminAddr) go func() { serveErr <- srv.ListenAndServeTLS("", "") }() } else { srv.Addr = *addr log.Printf("serving http on %s (admin on %s)", *addr, *adminAddr) go func() { serveErr <- srv.ListenAndServe() }() }
// Graceful shutdown: stop accepting new connections and let in-flight requests // drain (bounded). Long-lived SSE streams exit cooperatively via a.shutdown // (srv.Shutdown doesn't cancel request contexts); anything still in flight is // force-closed when the timeout elapses, then the process exits and the // background tickers die with it. ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM) defer stop() select { case err := <-serveErr: if err != nil && err != http.ErrServerClosed { log.Fatal(err) } case <-ctx.Done(): stop() // a second signal now force-quits log.Printf("shutting down…") shutCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second) defer cancel() if err := srv.Shutdown(shutCtx); err != nil { log.Printf("graceful shutdown: %v", err) } }
// Flush any buffered spans before exit (no-op when tracing is off). flushCtx, cancelFlush := context.WithTimeout(context.Background(), 5*time.Second) defer cancelFlush() if err := otelShutdown(flushCtx); err != nil { log.Printf("otel shutdown: %v", err) }}
// withSecurity sets baseline security response headers on every response and// applies a CSRF Origin check to state-changing command POSTs.//// The CSP deliberately omits script-src: Datastar evaluates its data-*// expressions and runs server-pushed <script> patches (e.g. the scroll-to-top// via ExecuteScript), so a strict script-src would break the app. It would// need careful tailoring (script-src 'unsafe-eval' plus a nonce scheme) before// it could be enabled. The scripts-free directives below are still free// defense-in-depth; frame-ancestors duplicates X-Frame-Options for clickjacking.func (a *app) withSecurity(next http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { h := w.Header() h.Set("X-Content-Type-Options", "nosniff") h.Set("X-Frame-Options", "DENY") h.Set("Referrer-Policy", "same-origin") h.Set("Content-Security-Policy", "frame-ancestors 'none'; base-uri 'self'; object-src 'none'; form-action 'self'") if a.auth.secure() { h.Set("Strict-Transport-Security", "max-age=63072000; includeSubDomains") } if r.Method == http.MethodPost && (strings.HasPrefix(r.URL.Path, "/cmd/") || r.URL.Path == "/auth/logout") && !a.sameOrigin(r) { http.Error(w, "cross-origin request rejected", http.StatusForbidden) return } next.ServeHTTP(w, r) })}
// sameOrigin is a CSRF check for state-changing POSTs that complements the// SameSite=Lax auth cookie (which Lax alone does not extend to same-site// subdomains). Browsers always send Sec-Fetch-Site (preferred) and Origin on// these requests, so a forged cross-origin write is caught; non-browser clients// (curl, the load harness) send neither and are allowed through, since CSRF// requires a victim's browser, which always sets these headers.func (a *app) sameOrigin(r *http.Request) bool { if s := r.Header.Get("Sec-Fetch-Site"); s != "" { return s == "same-origin" || s == "none" } if o := r.Header.Get("Origin"); o != "" { return o == a.baseURL } return true}
// ---- session cookie ----
// sessionFor resolves the per-tab view session for a request.//// Trust boundary: the sid is client-chosen and unauthenticated — anyone who// knows (or guesses) another tab's UUID can steer that tab's *view* state// (search query, open issue, filters). That is acceptable here by design// because a session holds nothing sensitive and grants nothing: identity comes// only from the HMAC-signed dbugs_auth cookie, and writes are rate-limited per// writer identity (see writeLimiter), never per sid. Do not copy this pattern// into an app where session state carries data or authority — there the// session key must be a server-issued secret.func (a *app) sessionFor(w http.ResponseWriter, r *http.Request) *Session { // Per-tab: the client sends a sessionStorage-backed `sid` signal, so each tab // gets its own server-side search session (auth identity stays shared via the // separate dbugs_auth cookie). Fall back to a cookie for requests with no sid. if sid := readSid(r); sid != "" { return a.hub.getOrCreate(sid) } if c, err := r.Cookie(cookieName); err == nil && c.Value != "" { return a.hub.getOrCreate(c.Value) } id := newSessionID() http.SetCookie(w, &http.Cookie{ Name: cookieName, Value: id, Path: "/", HttpOnly: true, SameSite: http.SameSiteLaxMode, Secure: a.auth.secure(), }) return a.hub.getOrCreate(id)}
// assetVer cache-busts the static URLs: /static is served with a 1h max-age, so// without a per-build query string a CSS/JS change would stay stale for up to an// hour after deploy. Set once at startup → every deploy (restart) gets a new// token → browsers re-fetch changed assets immediately.var assetVer = strconv.FormatInt(time.Now().Unix(), 36)
// isWebKit reports whether the request is from Safari / a WebKit-based browser// (incl. all iOS browsers). WebKit buffers a streamed fetch response until more// data arrives, so these clients get the fast keepalive burst in handleStream// that flushes the buffer for live updates (they still get brotli like everyone;// server-render covers first paint). Chrome/Edge/Brave include "Chrome" in the// UA; Firefox has no AppleWebKit.func isWebKit(r *http.Request) bool { ua := r.Header.Get("User-Agent") return strings.Contains(ua, "AppleWebKit") && !strings.Contains(ua, "Chrome") && !strings.Contains(ua, "Chromium")}
// readSid extracts the per-tab `sid` signal from the request without consuming// the body the command handler still needs: Datastar puts signals in the// ?datastar= query for GET (stream) and in the JSON body for POST (commands), so// for POST we buffer and restore the body. The sid is untrusted client input;// see sessionFor for what that does and does not grant.func readSid(r *http.Request) string { raw := r.URL.Query().Get("datastar") if raw == "" && r.Body != nil && r.Method != http.MethodGet { // Bound the read independently of the handler's MaxBytesReader: not every // command handler wraps the body before sessionFor runs, so cap here so a // hostile client can't stream an unbounded body into memory via readSid. b, err := io.ReadAll(io.LimitReader(r.Body, maxCmdBody)) if err != nil { return "" } r.Body = io.NopCloser(bytes.NewReader(b)) // restore for the handler's ReadSignals raw = string(b) } if raw == "" { return "" } var s struct { Sid string `json:"sid"` } _ = json.Unmarshal([]byte(raw), &s) return s.Sid}
// ---- index ----
func (a *app) handleIndex(w http.ResponseWriter, r *http.Request) { if r.URL.Path != "/" { http.NotFound(w, r) return } // Reload restore: if the navigating tab stamped its sid into the dbugs_tab // cookie on pagehide, SSR that tab's live session so first paint already // matches what the stream will push. peek, never create — the cookie is // client-chosen, and view state is non-sensitive by design (see sessionFor). st := newSessionState() seed := 0 if c, err := r.Cookie(tabCookieName); err == nil && c.Value != "" { if s, ok := a.hub.peek(c.Value); ok { st = s.snapshot() seed = st.Selected } // One-shot: expire it immediately so a NEW tab opened within the TTL // doesn't adopt this tab's view (pagehide re-stamps before every // same-tab navigation anyway). http.SetCookie(w, &http.Cookie{Name: tabCookieName, Value: "", Path: "/", MaxAge: -1}) } a.renderPage(w, r, st, seed, false)}
// handleIssue serves the canonical, shareable URL for an issue: /i/{shortID}. The// issue is the resource; this entry point SSR-renders the app focused on it and// seeds the live session (via seedSelect) so the stream agrees with first paint.// The session — not the URL — remains the resource, so we never rewrite the URL// as the user navigates afterwards.func (a *app) handleIssue(w http.ResponseWriter, r *http.Request) { id, err := strconv.Atoi(r.PathValue("id")) if err != nil || id <= 0 { http.NotFound(w, r) return } // Existence check only: the result is discarded because renderPage → // renderRegions re-fetches the issue through the cached render pipeline. // We fetch here anyway so a missing issue is a real HTTP 404, not a soft // empty state rendered into the page. if _, derr := a.reads.GetIssue(r.Context(), id); derr != nil { if errors.Is(derr, sql.ErrNoRows) { http.NotFound(w, r) return } log.Printf("issue %d: %v", id, derr) http.Error(w, "internal error", http.StatusInternalServerError) return } // Same reload-restore as handleIndex: a permalink opened in a tab that // already has session state (filters, search) SSRs that state with the // linked issue swapped in, instead of flashing defaults and converging. st := newSessionState() if c, cerr := r.Cookie(tabCookieName); cerr == nil && c.Value != "" { if s, ok := a.hub.peek(c.Value); ok { st = s.snapshot() } http.SetCookie(w, &http.Cookie{Name: tabCookieName, Value: "", Path: "/", MaxAge: -1}) } st.Selected = id a.renderPage(w, r, st, id, true)}
// pageSignals builds the initial data-signals payload for index.html.// Marshaled server-side rather than interpolated field-by-field into a JS// object literal in the template: html/template only HTML-escapes inside// data-* attributes, so a session-derived string like the search query could// break out of a JS string literal there (the same trap documented on// data-name in fragments.html). json.Marshal escapes everything JS needs// (including U+2028/9), and a JSON object is a valid Datastar expression.// Server-state mirrors (query/status/cur/active/_stats) are seeded from the// session so hydration and the stream's first push change nothing visible.func pageSignals(initial SessionState, seedSelect int) ([]byte, error) { return json.Marshal(map[string]any{ // server-state mirrors ($status needs none: the topbar status nav is a // server-rendered morph region, like #facets) "query": initial.Query, "cur": seedSelect, "active": seedSelect, "_stats": initial.StatsOpen, // client-owned UI state (see the CQRS comment in index.html) "sid": "", "palette": "", "pane": "", "dcur": 0, "draft": "", "compose": map[string]any{"title": "", "desc": "", "labels": []string{}}, "edit": map[string]any{"title": "", "desc": "", "status": "open", "labels": []string{}}, // transient in-flight/scratch flags "_busy": false, "_notice": "", "_key": "", "_copied": false, "_cmd": false, "_listCmd": false, "_searching": false, "_commenting": false, "_creating": false, "_saving": false, "_focusComments": false, "_ptr": "", "_lastActive": seedSelect, })}
// renderPage server-renders the COMPLETE page for the given initial view, so first// paint never depends on the SSE stream (WebKit buffers streamed fetches; the// stream only drives live *updates*). seedSelect (>0) seeds the $active/$cur// signals so the selected row is highlighted at first paint. seedPost// additionally makes data-init adopt that issue on the live session before// opening the stream — needed on /i/{id}, where the SSR state is NOT the tab// session's; the reload-restore path SSRs the tab session itself, so posting// would be a redundant round trip.func (a *app) renderPage(w http.ResponseWriter, r *http.Request, initial SessionState, seedSelect int, seedPost bool) { vw := a.viewerFor(r) rs, err := a.renderRegions(r.Context(), initial, vw) if err != nil { log.Printf("page render: %v", err) http.Error(w, "page render failed", http.StatusInternalServerError) return } sig, err := pageSignals(initial, seedSelect) if err != nil { log.Printf("page render: %v", err) http.Error(w, "page render failed", http.StatusInternalServerError) return } data := struct { viewer AssetVer string SeedSelect int SeedPost bool Signals string // initial data-signals payload (JSON; attr-escaped by the template) StatusNav template.HTML Facets template.HTML List template.HTML Detail template.HTML }{vw, assetVer, seedSelect, seedPost, string(sig), template.HTML(rs.statusNav), template.HTML(rs.facets), template.HTML(rs.list), template.HTML(rs.detail)} // Render to a buffer first: writing straight to w commits a 200 on the // first byte, after which a mid-render failure could only append an error // message to a truncated page. Buffering guarantees a real 500 instead. var buf bytes.Buffer if err := tmpl.ExecuteTemplate(&buf, "index.html", data); err != nil { log.Printf("page render: %v", err) http.Error(w, "page render failed", http.StatusInternalServerError) return } w.Header().Set("Content-Type", "text/html; charset=utf-8") // A failed write means the client went away mid-response — not a server // error, nothing to do. _, _ = buf.WriteTo(w)}
// ---- read stream (long-lived projection push) ----
func (a *app) handleStream(w http.ResponseWriter, r *http.Request) { // Connection cap: shed load with a 503 past the limit instead of OOMing. n := a.stats.streams.Add(1) defer a.stats.streams.Add(-1) if a.maxConns > 0 && n > int64(a.maxConns) { http.Error(w, "server at capacity, retry shortly", http.StatusServiceUnavailable) return }
sess := a.sessionFor(w, r)
// The countingWriter sits under the SDK's compression writer, so it tallies // the actual wire bytes — compressed for every browser now; raw only when the // -compress=false kill-switch is set. cw := &countingWriter{ResponseWriter: w, n: &a.stats.wireBytes} var sse *datastar.ServerSentEventGenerator // Brotli for every browser, including WebKit/Safari. WebKit buffers streamed // fetch responses (compressed or not) until some internal threshold, which // strands SMALL trailing events — that's handled structurally, not here: // first paint is server-rendered (never depends on the stream), everything // user-visible in a push is morphed HTML or a signal sent BEFORE the // element patch (see pushProjection's push-order comment), and the big // morph flushes the lot. Only the -compress=false kill-switch serves // uncompressed (debug/fallback). if !a.compress { sse = datastar.NewSSE(cw, r) } else { // Adaptive quality: brotli memory/CPU per connection scales with quality // (q2≈0.7MB, q0≈0.37MB). Under heavy load, new streams use q0 so we hold // ~2× more — full quality stays the default when there's room. The small // LGWin (brwin=16 → 64 KB) covers our ~40 KB fragments, so far less // per-conn memory than brotli's 4 MiB-window default. brq := a.brQ if a.maxConns > 0 && n > int64(a.maxConns)*3/4 { brq = 0 } sse = datastar.NewSSE(cw, r, datastar.WithCompression( datastar.WithBrotli( datastar.WithBrotliLevel(brq), datastar.WithBrotliLGWin(a.brWin), ), datastar.WithGzip(), // fallback for clients that don't accept br ), ) }
ch := sess.subscribe()
// Auth identity is fixed for the connection's life (a sign-in/out is a // full-page reload → new connection), so capture it once and render // auth-gated detail server-side — no client auth signals. vw := a.viewerFor(r) sess.setViewer(vw) // for realtime presence (who's viewing)
// Presence: this stream is a new viewer of whatever issue the session has // open, and on disconnect it leaves — wake the other watchers of that issue // so their "N viewing" updates. Disconnect runs after unsubscribe so this // session is already excluded from the recount. if sel := sess.snapshot().Selected; sel > 0 { a.hub.notifyDetailWatchers(sel) } defer func() { sel := sess.snapshot().Selected sess.unsubscribe(ch) if sel > 0 { a.hub.notifyDetailWatchers(sel) } }()
ctx := r.Context() ss := &streamState{webkit: isWebKit(r)} if err := a.pushProjection(ctx, sse, sess, ss, vw); err != nil { return }
// Periodic keepalive so a NAT/proxy doesn't drop an idle stream. It also // bounds how long WebKit can sit on a buffered post-element signal tail // (see pushProjection). `_ka` is underscore-prefixed → never sent back to // the server nor included in the stream URL. ka := time.NewTicker(15 * time.Second) defer ka.Stop() kaCount := 0 for { select { case <-ctx.Done(): return case <-a.shutdown: return case <-ch: if err := a.pushProjection(ctx, sse, sess, ss, vw); err != nil { return } case <-ka.C: if err := sse.MarshalAndPatchSignals(map[string]any{"_ka": kaCount}); err != nil { return } kaCount++ } }}
// streamState remembers the per-region hash of what this connection last sent.// A region whose bytes are unchanged is left out of the next patch, so (a) idle// connections cost ~0 under fan-out, and (b) an actively-edited form in an// unchanged #detail is never re-morphed when only the list/facets/stats change.type streamState struct { facetsH, listH, detailH, statsH, paletteH, helpH, statusNavH uint64 activeSig int // last Selected pushed to $active (marks the loaded issue's row) synced bool // first push done — a fresh connection re-syncs $cur/$active unconditionally webkit bool // trailing no-op nudge after each push (WebKit buffers streamed fetches)}
func hashStr(s string) uint64 { h := fnv.New64a() h.Write([]byte(s)) return h.Sum64()}
// viewerFor derives the server-side auth context from the request.func (a *app) viewerFor(r *http.Request) viewer { if a.auth.enabled { if u := a.auth.user(r); u != nil { return viewer{Login: u.Login, Avatar: u.Avatar, AuthOn: true, CanWrite: true} } return viewer{AuthOn: true} } if a.devUser != "" { // local dev without OAuth return viewer{Login: a.devUser, CanWrite: true} } return viewer{} // browse-only}
func (a *app) pushProjection(ctx context.Context, sse *datastar.ServerSentEventGenerator, sess *Session, ss *streamState, vw viewer) error { // Root span per push (the /stream request itself is excluded from HTTP // tracing — one span for a connection's whole life would be useless). This is // the fan-out half of a write's latency story: writer.flush commits, the hub // wakes dirty sessions, and each woken stream shows up here. ctx, span := tracer.Start(ctx, "sse.push") defer span.End()
state := sess.snapshot() rs, err := a.renderRegions(ctx, state, vw) if err != nil { span.RecordError(err) log.Printf("projection: %v", err) return err }
// Everything after render is the send half: diff the regions, assemble the // one combined patch, and PatchElements' marshal + brotli + socket write, // plus the trailing signal patches. A child of sse.push covering the time // render.regions doesn't — so the waterfall tiles instead of leaving the // push bar half-empty. (Its defer runs before sse.push's, so it nests.) _, sendSpan := tracer.Start(ctx, "sse.send") defer sendSpan.End()
// Combine only the regions whose bytes changed into ONE patch (atomic — no // half-applied view), and skip the rest (unchanged forms stay untouched). fh, lh, dh := hashStr(rs.facets), hashStr(rs.list), hashStr(rs.detail) ph, hh, snh := hashStr(rs.palette), hashStr(rs.help), hashStr(rs.statusNav) var sh uint64 if rs.stats != "" { sh = hashStr(rs.stats) } var b strings.Builder raw := 0 if fh != ss.facetsH { b.WriteString(rs.facets) raw += len(rs.facets) } if lh != ss.listH { b.WriteString(rs.list) raw += len(rs.list) } if dh != ss.detailH { b.WriteString(rs.detail) raw += len(rs.detail) } if rs.stats != "" && sh != ss.statsH { b.WriteString(rs.stats) raw += len(rs.stats) } if ph != ss.paletteH { b.WriteString(rs.palette) raw += len(rs.palette) } if hh != ss.helpH { b.WriteString(rs.help) raw += len(rs.help) } if snh != ss.statusNavH { b.WriteString(rs.statusNav) raw += len(rs.statusNav) } sent := false // Push order is load-bearing for WebKit: Safari buffers a streamed fetch // client-side until enough bytes accumulate (compressed or not — measured), // so a SMALL patch sent AFTER the element morph sits undelivered until the // next push or the 15s keepalive. Small signal patches therefore go BEFORE // the elements — the big morph is the tail that flushes them through // Safari's buffer in the same chunk. (This is also why the topbar status // nav is a morph region, not a $status signal: morphed HTML rides the // combined element patch, which always delivers.) $active/$cur are the // exception and MUST stay after the elements: the client's $_focusComments // handler runs on the $active patch and needs the NEW detail DOM (see the // data-on-signal-patch comment in index.html). // // First-push re-sync for the remaining server-state mirrors. A same-tab // reload usually SSRs the tab's real session via the dbugs_tab restore // cookie (see handleIndex), making this push a near-no-op; it remains the // safety net for every path SSR can't cover — a new tab, an expired or // stripped cookie, an evicted session — where the page painted the DEFAULT // projection and converges here: the search box re-fills from the session // query and the stats panel re-opens. ($cur/$active sync after the // elements; status needs no sync — it's a morph region.) if !ss.synced { init := map[string]any{} if state.Query != "" { init["query"] = state.Query } if state.StatsOpen { init["_stats"] = true } if len(init) > 0 { if err := sse.MarshalAndPatchSignals(init); err != nil { return err } sent = true } } if b.Len() > 0 { if err := sse.PatchElements(b.String()); err != nil { // scrollReset is left intact so a reconnecting stream still scrolls. return err } // Commit hashes only after a successful send. ss.facetsH, ss.listH, ss.detailH = fh, lh, dh ss.paletteH, ss.helpH, ss.statusNavH = ph, hh, snh if rs.stats != "" { ss.statsH = sh } a.stats.pushes.Add(1) a.stats.rawBytes.Add(int64(raw)) sent = true } // A filter/sort/search flagged the session for a scroll-to-top. Claim it only // after a successful morph so it lands on the new content, not the old; the // atomic Swap consumes it once even if more than one stream projects this // session. If the script send fails, restore the flag so a reconnecting stream // retries instead of silently dropping the scroll. if sess.scrollReset.Swap(false) { if err := sse.ExecuteScript(scrollListTopJS); err != nil { sess.scrollReset.Store(true) return err } sent = true } // Two distinct list-row states, two signals (the list HTML is shared across // sessions via the ListCache, so per-session row state cannot be baked into // the fragment — it rides signals): // - $cur — the CURSOR, client-owned. j/k and clicks move it freely with // no round trip; the server writes it only below, for // selections the client's cursor didn't originate. // - $active — the LOADED issue (mirrors Selected), server-owned. Marks the // open issue's row regardless of where the cursor wanders. if state.Selected != ss.activeSig || (!ss.synced && state.Selected > 0) { if err := sse.MarshalAndPatchSignals(map[string]any{"active": state.Selected}); err != nil { return err } // Adopt the cursor only for programmatic selections — palette pick, // permalink seed, issue-create (CurSynced=false, see doSelect) — or on a // connection's first push (page load / reconnect), where the client's // cursor needs a re-sync. A click/l selection is NOT echoed: the echo // would land ~RTT stale, clobbering a cursor that may have moved on and // yanking the list scroll backwards. if state.Selected > 0 && (!state.CurSynced || !ss.synced) { if err := sse.MarshalAndPatchSignals(map[string]any{"cur": state.Selected}); err != nil { return err } if err := sse.ExecuteScript(fmt.Sprintf(`document.querySelector('#list [data-row="%d"]')?.scrollIntoView({block:'center'})`, state.Selected)); err != nil { return err } } ss.activeSig = state.Selected sent = true } ss.synced = true // Fresh content arriving IS the end of "loading" from this connection's // perspective — clear the in-flight UI flags in the same push. The command // response also clears them (it must: dedup can mean no push ever comes for // an unchanged view), but over a slow network that response closes long // after this push has painted, leaving indicators trailing the content they // were announcing. Form indicators (_commenting/_creating/_saving) are NOT // cleared here: for writes the response is the commit ack, which is the // honest end of those. (A push triggered by someone else's update can clear // a still-in-flight flag early — cosmetic, and that command's own // response/projection still lands.) if sent { if err := sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_cmd": false, "_listCmd": false, "_searching": false}); err != nil { return err } } // Trailing no-op nudge for WebKit's stream buffering. NOT a cure for small // tails — WebKit holds a streamed fetch's bytes until some threshold, and // neither this no-op nor a 1 KB random pad (tried, measured, failed on iOS // 18) reliably crosses it. The real mitigations are structural: anything // user-visible is morphed HTML or rides BEFORE the element patch, so the // big morph is what flushes it (see the push-order comment above). The // signals after the elements ($active/$cur sync, busy clears) may lag on // WebKit until the next push — cosmetic by design. if sent && ss.webkit { _ = sse.MarshalAndPatchSignals(map[string]any{"_ka": 1}) } // sent=false pushes are dedup hits: the session was woken but this // connection's view didn't change — cheap, but visible here if they dominate. // (No padding for those either: nothing visible is pending delivery.) span.SetAttributes( attribute.Bool("push.sent", sent), attribute.Int("push.raw_bytes", raw), ) return nil}
// ---- command plumbing ----
// doStats toggles the server-side debug-panel flag, so the projection includes// the stats fragment and the sampler keeps it live — all over the one pipe.func (a *app) doStats(s *Session, r *http.Request) { s.withState(func(st *SessionState) { st.StatsOpen = !st.StatsOpen })}
// maxCmdBody caps the request body for command POSTs. Signal payloads are tiny// (a draft, a title, a few labels); this stops a hostile client from streaming// an unbounded body into memory.const maxCmdBody = 64 << 10 // 64 KB
// maxWindow caps the visible list window so repeated /cmd/more can't grow the// query result set (and the rendered payload) without bound.const maxWindow = 500
// loadMoreStep is how many rows each /cmd/more adds. Bigger than the initial page// so a fast scroll always has several screens of buffer below it before it can// outrun the next load (the initial page stays small for a fast first paint).const loadMoreStep = 150
// validLabel reports whether name is a real catalog label. User-supplied label// names are checked against this so the Labels set and per-label query clauses// stay bounded to the catalog.func (a *app) validLabel(name string) bool { for _, l := range a.catalog { if l.Name == name { return true } } return false}
// cleanLabels returns the unique, catalog-valid subset of in — bounding both the// write-time insert loop and the stored label set to the catalog.func (a *app) cleanLabels(in []string) []string { seen := make(map[string]bool, len(in)) out := make([]string, 0, len(in)) for _, l := range in { if !seen[l] && a.validLabel(l) { seen[l] = true out = append(out, l) } } return out}
// runCmd wraps a mutation: apply it to the session, notify streams, return an// empty SSE 200 (Datastar is happy with a no-event stream response). closeOv// dismisses any open palette/help first — so picking an action from the palette// closes it (the palette's own query/nav endpoints pass closeOv=false to stay// open while you interact with them).func (a *app) runCmd(closeOv bool, mut func(*Session, *http.Request)) http.HandlerFunc { return func(w http.ResponseWriter, r *http.Request) { r.Body = http.MaxBytesReader(w, r.Body, maxCmdBody) sess := a.sessionFor(w, r) if closeOv { sess.closeOverlays() } mut(sess, r) sess.notify() // Clear the loading bar in the command's own response, not the // projection — so the projection stream can skip connections whose view // didn't change (dedup) without leaving a stuck spinner. sse := datastar.NewSSE(w, r) _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false}) }}
// cmd is runCmd for concrete actions: it closes the command palette/help.func (a *app) cmd(mut func(*Session, *http.Request)) http.HandlerFunc { return a.runCmd(true, mut)}
// cmdKeep is runCmd for the palette's own query/nav, which must leave it open.func (a *app) cmdKeep(mut func(*Session, *http.Request)) http.HandlerFunc { return a.runCmd(false, mut)}
// scrollListTopJS resets the list scroll; pushed WITH the projection (see// pushProjection) so it lands after the new content morphs in, not before.const scrollListTopJS = "document.getElementById('list')?.scrollTo(0, 0)"
// cmdScrollTop is cmd() for commands that change the *result set*// (filter/sort/search): it flags the session so the resulting projection scrolls// the list back to the top (the morph otherwise preserves #list.scrollTop, landing// you mid-list). Load-more and select keep their scroll (they use cmd()).func (a *app) cmdScrollTop(mut func(*Session, *http.Request)) http.HandlerFunc { return a.cmd(func(s *Session, r *http.Request) { mut(s, r) s.scrollReset.Store(true) })}
// ---- command system: keyboard dispatch + palette ----
// handleKey resolves a key combo (in ?k=) against the registry and runs the// matching command. It is NOT the cmd() wrapper: it must conditionally// ExecuteScript (focus) and must NOT auto-close overlays, since opening the// palette/help is itself a key command.func (a *app) handleKey(w http.ResponseWriter, r *http.Request) { r.Body = http.MaxBytesReader(w, r.Body, maxCmdBody) sess := a.sessionFor(w, r) combo := strings.TrimSpace(r.URL.Query().Get("k")) ctx := cmdCtx{st: sess.snapshot(), vw: a.viewerFor(r)} c := resolveKey(combo, ctx)
sse := datastar.NewSSE(w, r) if c == nil { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false}) return } payload := map[string]any{"_busy": false} if c.Run != nil { for k, v := range c.Run(a, sess, r) { payload[k] = v } } if c.Scroll { sess.scrollReset.Store(true) } sess.notify() if c.Script != "" { _ = sse.ExecuteScript(c.Script) } _ = sse.MarshalAndPatchSignals(payload)}
// doPaletteQuery records the palette input text (mirrors $palette, like doSearch// mirrors $query) and resets the highlight to the top.func (a *app) doPaletteQuery(s *Session, r *http.Request) { var sig struct { Palette string `json:"palette"` } _ = datastar.ReadSignals(r, &sig) s.withState(func(st *SessionState) { st.PaletteQuery = sig.Palette st.PaletteIndex = 0 })}
// doPaletteNav moves the palette highlight, clamped to the current result count.func (a *app) doPaletteNav(s *Session, r *http.Request) { st := s.snapshot() if !st.PaletteOpen { return } total := len(a.paletteItems(r.Context(), st, a.viewerFor(r))) up := r.URL.Query().Get("d") == "up" s.withState(func(st *SessionState) { if up { st.PaletteIndex-- } else { st.PaletteIndex++ } if st.PaletteIndex < 0 { st.PaletteIndex = 0 } if total > 0 && st.PaletteIndex > total-1 { st.PaletteIndex = total - 1 } })}
// ---- write command: add a comment ----
// writerName resolves the display name for a write and enforces auth. When auth// is enabled and the request isn't signed in, it pushes a sign-in notice and// returns ok=false so the caller aborts (the UI also gates the inputs).func (a *app) writerName(r *http.Request, sse *datastar.ServerSentEventGenerator, action string) (string, bool) { if a.auth.enabled { if u := a.auth.user(r); u != nil { return u.Login, true } _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "Sign in to " + action + "."}) return "", false } if a.devUser != "" { // local dev without OAuth return a.devUser, true } _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "Writing is disabled (no auth configured)."}) return "", false}
func (a *app) handleComment(w http.ResponseWriter, r *http.Request) { r.Body = http.MaxBytesReader(w, r.Body, maxCmdBody) sess := a.sessionFor(w, r) var sig struct { Draft string `json:"draft"` } _ = datastar.ReadSignals(r, &sig)
state := sess.snapshot() body := strings.TrimSpace(sig.Draft)
sse := datastar.NewSSE(w, r) if state.Selected == 0 || body == "" { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false}) return // nothing to do } body, trimNote := truncateNoted(body, 2000, "Comment") author, ok := a.writerName(r, sse, "comment") if !ok { return } if a.writeLimit && !a.writes.allow(author, time.Now()) { // Confirmed-not-optimistic: tell the user, leave their draft intact. _ = sse.MarshalAndPatchSignals(map[string]any{ "_busy": false, "_notice": "You're commenting too fast — give it a sec.", }) return } issueShort := state.Selected nowMs := time.Now().UTC().UnixMilli()
err := a.writer.Submit(r.Context(), writeOp{ affectsCounts: false, // comments don't change issue counts apply: func(ctx context.Context, tx *sql.Tx) error { var issueID int if e := tx.QueryRowContext(ctx, `SELECT id FROM issues WHERE short_id = ?`, issueShort).Scan(&issueID); e != nil { return e } _, e := tx.ExecContext(ctx, `INSERT INTO comments(issue_id, author_id, author_name, body, created) VALUES(?, 0, ?, ?, ?)`, issueID, author, body, nowMs) return e }, }) if err != nil { _ = sse.MarshalAndPatchSignals(map[string]any{ "_busy": false, "_notice": "Couldn't post right now — try again.", }) return }
// Scoped push: a comment only changes this issue's detail, so wake just the // sessions viewing it (not the whole fleet). The new comment arrives on their // stream; this command's response only clears the draft. a.hub.notifyDetailWatchers(issueShort) _ = sse.MarshalAndPatchSignals(map[string]any{"draft": "", "_notice": trimNote, "_busy": false})}
// addAuthor inserts name into the author-facet datalist if it's new. The list// is a startup snapshot (AllAuthors) refreshed only here, on issue create —// the one path that can mint an author. Copy-on-write keeps the sorted slice// immutable, so concurrent renders read it without locking.func (a *app) addAuthor(name string) { for { cur := a.authors.Load() i, found := slices.BinarySearch(*cur, name) if found { return } next := slices.Insert(slices.Clone(*cur), i, name) if a.authors.CompareAndSwap(cur, &next) { return } }}
// handleCreate inserts a new issue. Unlike comments this changes the issue set,// so the write op sets affectsCounts=true → bumps dataVersion → the count cache// is invalidated and every session's list re-projects with the new row on top.func (a *app) handleCreate(w http.ResponseWriter, r *http.Request) { r.Body = http.MaxBytesReader(w, r.Body, maxCmdBody) sess := a.sessionFor(w, r) var sig struct { Compose struct { Title string `json:"title"` Desc string `json:"desc"` Labels []string `json:"labels"` } `json:"compose"` } _ = datastar.ReadSignals(r, &sig)
title := strings.TrimSpace(sig.Compose.Title) desc := strings.TrimSpace(sig.Compose.Desc) labels := a.cleanLabels(sig.Compose.Labels)
sse := datastar.NewSSE(w, r) if title == "" { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "Title is required."}) return } title, titleNote := truncateNoted(title, 200, "Title") desc, descNote := truncateNoted(desc, 4000, "Description") trimNote := strings.TrimSpace(titleNote + " " + descNote) creator, ok := a.writerName(r, sse, "create an issue") if !ok { return } if a.writeLimit && !a.writes.allow(creator, time.Now()) { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "Slow down a moment, then try again."}) return } nowMs := time.Now().UTC().UnixMilli() var newShort int
err := a.writer.Submit(r.Context(), writeOp{ affectsCounts: true, // new issue changes the counts // Scoped invalidation: a create has no pre-image; the post-image is the // handler's own inputs (always open, these labels, this creator). images: &opImages{post: &issueImage{Open: true, Labels: labels, Author: creator}}, apply: func(ctx context.Context, tx *sql.Tx) error { var maxShort int if e := tx.QueryRowContext(ctx, `SELECT COALESCE(MAX(short_id), 1000) FROM issues`).Scan(&maxShort); e != nil { return e } newShort = maxShort + 1 res, e := tx.ExecContext(ctx, ` INSERT INTO issues(short_id, title, description, open, creator_id, assignee_id, created, modified, creator_name) VALUES(?, ?, ?, 1, 0, NULL, ?, ?, ?)`, newShort, title, desc, nowMs, nowMs, creator) if e != nil { return e } issueID, e := res.LastInsertId() if e != nil { return e } for _, lbl := range labels { if _, e := tx.ExecContext(ctx, `INSERT OR IGNORE INTO issue_labels(issue_id, label_id) SELECT ?, id FROM labels WHERE name = ?`, issueID, lbl); e != nil { return e } } // Labels are in; recompute the facet tokens (status/author/labels) so // the FTS index can filter this issue without touching the B-trees. if _, e := tx.ExecContext(ctx, refreshFacetsSQL, issueID); e != nil { return e } return nil }, }) if err != nil { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "Couldn't create the issue — try again."}) return }
a.addAuthor(creator) // a first-time creator should appear in the author facet now, not after restart // Close the composer and focus the new issue for its creator. This is a // programmatic selection (the creator's cursor is nowhere near the new row), // so the projection adopts the cursor. sess.withState(func(st *SessionState) { st.Composing = false st.Selected = newShort st.CurSynced = false }) // A new issue can appear in many lists; broadcast and let per-connection // dedup skip the views it didn't change. a.hub.notifyAll() _ = sse.MarshalAndPatchSignals(map[string]any{ "compose": map[string]any{"title": "", "desc": "", "labels": []string{}}, "_busy": false, "_notice": trimNote, })}
// handleEditStart opens the edit form for the selected issue and pre-fills the// edit.* signals with the issue's current values (the form binds to them). Shares// the ownership-checked startEdit path with the `e` shortcut (command.go); also// reachable from the palette, so it closes any open overlay.func (a *app) handleEditStart(w http.ResponseWriter, r *http.Request) { sess := a.sessionFor(w, r) sess.closeOverlays() sse := datastar.NewSSE(w, r) payload := a.startEdit(r.Context(), sess, a.viewerFor(r)) sess.notify() // render the edit form (or just the closed overlay) into the detail region if payload == nil { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false}) return } payload["_busy"] = false payload["_notice"] = "" _ = sse.MarshalAndPatchSignals(payload)}
// handleEditSave persists an edit. Like create it changes the issue set (status,// labels, and searchable text), so affectsCounts=true → count cache invalidates.func (a *app) handleEditSave(w http.ResponseWriter, r *http.Request) { r.Body = http.MaxBytesReader(w, r.Body, maxCmdBody) sess := a.sessionFor(w, r) var sig struct { Edit struct { Title string `json:"title"` Desc string `json:"desc"` Status string `json:"status"` Labels []string `json:"labels"` } `json:"edit"` } _ = datastar.ReadSignals(r, &sig)
state := sess.snapshot() title := strings.TrimSpace(sig.Edit.Title) desc := strings.TrimSpace(sig.Edit.Desc) open := sig.Edit.Status != "closed" labels := a.cleanLabels(sig.Edit.Labels)
sse := datastar.NewSSE(w, r) if state.Selected == 0 { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false}) return } if title == "" { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "Title is required."}) return } title, titleNote := truncateNoted(title, 200, "Title") desc, descNote := truncateNoted(desc, 4000, "Description") trimNote := strings.TrimSpace(titleNote + " " + descNote) me, ok := a.writerName(r, sse, "edit") if !ok { return } if a.writeLimit && !a.writes.allow(me, time.Now()) { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "Slow down a moment, then try again."}) return } // Ownership: only the issue's creator may edit it. Seeded issues (creator_id // set, creator_name NULL) are owned by no one and thus locked. octx, ospan := tracer.Start(r.Context(), "edit.ownership_check") var creator sql.NullString err := a.reads.db.QueryRowContext(octx, `SELECT creator_name FROM issues WHERE short_id = ?`, state.Selected).Scan(&creator) ospan.End() if err != nil { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "Issue not found."}) return } if !creator.Valid || creator.String != me { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "You can only edit issues you created."}) return } shortID := state.Selected nowMs := time.Now().UTC().UnixMilli()
// Scoped invalidation: the pre-image is read inside the transaction (below), // before the UPDATE; the post-image is the handler's own inputs. The creator // never changes on edit, so the post author is the pre author. imgs := &opImages{} err = a.writer.Submit(r.Context(), writeOp{ affectsCounts: true, images: imgs, apply: func(ctx context.Context, tx *sql.Tx) error { var issueID int if e := tx.QueryRowContext(ctx, `SELECT id FROM issues WHERE short_id = ?`, shortID).Scan(&issueID); e != nil { return e } pre, e := readIssueImage(ctx, tx, issueID) if e != nil { return e } imgs.pre = pre imgs.post = &issueImage{Open: open, Labels: labels, Author: pre.Author} if _, e := tx.ExecContext(ctx, `UPDATE issues SET title=?, description=?, open=?, modified=? WHERE id=?`, title, desc, boolToInt(open), nowMs, issueID); e != nil { return e } if _, e := tx.ExecContext(ctx, `DELETE FROM issue_labels WHERE issue_id=?`, issueID); e != nil { return e } for _, lbl := range labels { if _, e := tx.ExecContext(ctx, `INSERT OR IGNORE INTO issue_labels(issue_id, label_id) SELECT ?, id FROM labels WHERE name = ?`, issueID, lbl); e != nil { return e } } // Status and labels may both have changed; recompute the facet tokens. if _, e := tx.ExecContext(ctx, refreshFacetsSQL, issueID); e != nil { return e } return nil }, }) if err != nil { _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": "Couldn't save — try again."}) return }
sess.withState(func(st *SessionState) { st.Editing = false }) // An edit can change title/labels/status → many lists; broadcast, dedup skips // the unaffected views (and the edited-out case is caught because the list // bytes actually change for affected slices). a.hub.notifyAll() _ = sse.MarshalAndPatchSignals(map[string]any{"_busy": false, "_notice": trimNote})}
func boolToInt(b bool) int { if b { return 1 } return 0}
// truncateNoted caps s like truncate and, when the input was actually trimmed,// also returns a user-facing note for the command's _notice signal — silent// truncation alters input without telling anyone, which is the one thing the// validate-in-handler pattern exists to surface. The inputs carry maxlength so// this rarely fires from the UI; multi-byte text can still exceed the server's// byte cap (maxlength counts UTF-16 units, the cap counts bytes).func truncateNoted(s string, n int, what string) (string, string) { if len(s) <= n { return s, "" } return truncate(s, n), what + " was too long and was trimmed."}
// truncate caps s at n bytes without splitting a UTF-8 rune mid-sequence.func truncate(s string, n int) string { if len(s) <= n { return s } for n > 0 && !utf8.RuneStart(s[n]) { n-- } return s[:n]}
// ---- individual commands ----
func (a *app) doSearch(s *Session, r *http.Request) { var sig struct { Query string `json:"query"` } _ = datastar.ReadSignals(r, &sig) s.withState(func(st *SessionState) { had := strings.TrimSpace(st.Query) != "" now := strings.TrimSpace(sig.Query) != "" st.Query = sig.Query st.Limit = defaultPageSize // reset window on a new search // Default to relevance ranking when a search begins; restore recency // when it's cleared. A user can still override via the sort buttons. if now && !had { st.SortField = "relevance" } else if !now && st.SortField == "relevance" { st.SortField = "modified" } })}
func (a *app) doStatus(s *Session, r *http.Request) { v := r.URL.Query().Get("v") if v != "open" && v != "closed" && v != "all" { return } s.withState(func(st *SessionState) { st.Status = v st.Limit = defaultPageSize })}
func (a *app) doToggleLabel(s *Session, r *http.Request) { name := r.URL.Query().Get("name") if name == "" || !a.validLabel(name) { return } s.withState(func(st *SessionState) { idx := -1 for i, l := range st.Labels { if l == name { idx = i break } } if idx >= 0 { st.Labels = append(st.Labels[:idx], st.Labels[idx+1:]...) } else { st.Labels = append(st.Labels, name) } st.Limit = defaultPageSize })}
func (a *app) doClearLabels(s *Session, r *http.Request) { s.withState(func(st *SessionState) { st.Labels = nil st.Limit = defaultPageSize })}
// doAuthor sets (or toggles off) the author filter. Value is a creator name; not// catalog-validated, since a click-to-filter target may be an author created// after startup. It's a single parameterized value, so garbage just yields no// matches — no injection or unbounded growth.func (a *app) doAuthor(s *Session, r *http.Request) { name := strings.TrimSpace(r.URL.Query().Get("name")) if name == "" { return } s.withState(func(st *SessionState) { if st.Author == name { st.Author = "" // toggle off } else { st.Author = name } st.Limit = defaultPageSize })}
func (a *app) doClearAuthor(s *Session, r *http.Request) { s.withState(func(st *SessionState) { st.Author = "" st.Limit = defaultPageSize })}
// doAuthorMe toggles the filter to the current viewer's own issues.func (a *app) doAuthorMe(s *Session, r *http.Request) { me := a.devUser if a.auth.enabled { u := a.auth.user(r) if u == nil { return // not signed in } me = u.Login } if me == "" { return } s.withState(func(st *SessionState) { if st.Author == me { st.Author = "" } else { st.Author = me } st.Limit = defaultPageSize })}
func (a *app) doSort(s *Session, r *http.Request) { field := r.URL.Query().Get("field") if field != "modified" && field != "created" && field != "relevance" { return } s.withState(func(st *SessionState) { st.SortField = field })}
func (a *app) doSortDir(s *Session, r *http.Request) { s.withState(func(st *SessionState) { if st.SortDir == "desc" { st.SortDir = "asc" } else { st.SortDir = "desc" } })}
func (a *app) doMore(s *Session, r *http.Request) { s.withState(func(st *SessionState) { if st.Limit < maxWindow { st.Limit += loadMoreStep } if st.Limit > maxWindow { st.Limit = maxWindow } })}
func (a *app) doSelect(s *Session, r *http.Request) { id, err := strconv.Atoi(strings.TrimSpace(r.URL.Query().Get("id"))) if err != nil { return } // Cursor provenance: a click or l/Enter sets $cur before posting, so the // request's cur signal already equals id — the client's cursor is where it // wants to be and the projection must NOT echo it back (over real latency a // stale echo lands after the cursor has moved on, yanking it backwards). A // palette pick or permalink seed arrives with a different (or zero) cur: // that's a programmatic selection and the cursor should follow it. var sig struct { Cur int `json:"cur"` } _ = datastar.ReadSignals(r, &sig) var old int s.withState(func(st *SessionState) { old = st.Selected st.Selected = id st.CurSynced = sig.Cur == id st.Composing = false // selecting an issue closes the composer st.Editing = false // and exits any edit in progress }) a.repaintPresence(old, id)}
func (a *app) doClose(s *Session, r *http.Request) { var old int s.withState(func(st *SessionState) { old = st.Selected st.Selected = 0 st.Editing = false }) a.repaintPresence(old, 0)}
// repaintPresence wakes the other watchers of the issue(s) whose viewer set just// changed (a session moved between issues), so everyone's "N viewing" updates.func (a *app) repaintPresence(old, cur int) { if old == cur { return } if old > 0 { a.hub.notifyDetailWatchers(old) } if cur > 0 { a.hub.notifyDetailWatchers(cur) }}
func (a *app) doCompose(s *Session, r *http.Request) { s.withState(func(st *SessionState) { st.Composing = true })}
func (a *app) doComposeCancel(s *Session, r *http.Request) { s.withState(func(st *SessionState) { st.Composing = false })}
func (a *app) doEditCancel(s *Session, r *http.Request) { s.withState(func(st *SessionState) { st.Editing = false })}