P4.2: HTML index at / — the install-page seed

GET / now serves a dense server-rendered console: each app with its
channels' current releases and every release's artifacts as direct
/download/<sha256> links. Read-only off the per-request db.json reload;
text escaped for HTML. A browser hitting the server root sees the store
instead of a 404.

src/dist.sx

@@ -45,7 +45,7 @@ emit_human :: (s: string, json_mode: bool) {
     if json_mode { eputs(s); } else { out(s); }
 }
 
-HELP :: "dist — application distribution CLI\n\nUsage:\n  dist <group> <command> [flags]\n\nGroups & commands:\n  ci\n    ci publish            publish a release from CI\n      --manifest <path>     publish manifest (dist.json) to read\n      --local-store <dir>   local artifact store + db.json directory\n  release\n    release promote       point a channel at a release\n      --app <slug>          app the channel belongs to\n      --channel <name>      channel to move\n      --release <id>        release id to promote\n      --local-store <dir>   local artifact store + db.json directory\n    release rollback      move a channel back to its previous release\n      --app <slug>          app the channel belongs to\n      --channel <name>      channel to roll back\n      --local-store <dir>   local artifact store + db.json directory\n  server\n    server run            serve the store read-only over HTTP (0.0.0.0)\n      --local-store <dir>   local artifact store + db.json directory\n      --port <n>            TCP port (default 8787)\n      routes: /healthz, /api/apps, /api/apps/<slug>, /download/<sha256>\n\nGlobal flags:\n  --json                  emit machine-readable JSON on stdout; human text to stderr\n  -h, --help              show this help and exit\n\nExit codes:\n  0   success\n  1   command failed (publish/promote/rollback aborted or server could not bind)\n  64  usage error (no command, or an unknown/missing command or flag)\n";
+HELP :: "dist — application distribution CLI\n\nUsage:\n  dist <group> <command> [flags]\n\nGroups & commands:\n  ci\n    ci publish            publish a release from CI\n      --manifest <path>     publish manifest (dist.json) to read\n      --local-store <dir>   local artifact store + db.json directory\n  release\n    release promote       point a channel at a release\n      --app <slug>          app the channel belongs to\n      --channel <name>      channel to move\n      --release <id>        release id to promote\n      --local-store <dir>   local artifact store + db.json directory\n    release rollback      move a channel back to its previous release\n      --app <slug>          app the channel belongs to\n      --channel <name>      channel to roll back\n      --local-store <dir>   local artifact store + db.json directory\n  server\n    server run            serve the store read-only over HTTP (0.0.0.0)\n      --local-store <dir>   local artifact store + db.json directory\n      --port <n>            TCP port (default 8787)\n      routes: / (HTML index), /healthz, /api/apps, /api/apps/<slug>, /download/<sha256>\n\nGlobal flags:\n  --json                  emit machine-readable JSON on stdout; human text to stderr\n  -h, --help              show this help and exit\n\nExit codes:\n  0   success\n  1   command failed (publish/promote/rollback aborted or server could not bind)\n  64  usage error (no command, or an unknown/missing command or flag)\n";
 
 // True if `name` appears as a token in `args`.
 has_flag :: (args: []string, name: string) -> bool {

src/server/distd.sx

@@ -5,6 +5,7 @@
 // Serves the state the CLI publishes — db.json metadata and the
 // content-addressed objects — over HTTP (src/server/http.sx):
 //
+//   GET /                    HTML index: apps, channels, releases, links
 //   GET /healthz             {"status":"ok"} — no store access
 //   GET /api/apps            {"apps":[...]} every app in the store
 //   GET /api/apps/<slug>     {"app":..,"releases":[..],"channels":[..]}
@@ -180,6 +181,103 @@ respond_render :: (client: s32, buf: string, n: s64, overflowed: bool) {
     http.respond(client, 200, "application/json", "", string.{ ptr = buf.ptr, len = n });
 }
 
+// ── HTML index (the install-page seed, subplan 04 Slice 5) ───────────
+
+// Escape &, <, >, " for HTML text/attribute positions. Returns `s`
+// unchanged (no copy) when nothing needs escaping.
+html_escape :: (s: string) -> string {
+    acc := "";
+    start := 0;
+    i := 0;
+    while i < s.len {
+        c := s[i];
+        rep := "";
+        if c == 38 { rep = "&amp;"; }    // &
+        if c == 60 { rep = "&lt;"; }     // <
+        if c == 62 { rep = "&gt;"; }     // >
+        if c == 34 { rep = "&quot;"; }   // "
+        if rep.len > 0 {
+            if i > start { acc = concat(acc, string.{ ptr = @s[start], len = i - start }); }
+            acc = concat(acc, rep);
+            start = i + 1;
+        }
+        i += 1;
+    }
+    if start == 0 { return s; }
+    if start < s.len { acc = concat(acc, string.{ ptr = @s[start], len = s.len - start }); }
+    return acc;
+}
+
+// First 12 hex chars of a digest, for display next to the full-link.
+short_sha :: (sha: string) -> string {
+    if sha.len < 12 { return sha; }
+    return string.{ ptr = sha.ptr, len = 12 };
+}
+
+INDEX_HEAD :: "<!doctype html><html><head><meta charset=\"utf-8\"><meta name=\"viewport\" content=\"width=device-width,initial-scale=1\"><title>dist</title><style>body{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;background:#101216;color:#d6dae1;margin:2rem auto;max-width:60rem;padding:0 1rem}h1{font-size:1.1rem;letter-spacing:.04em}h2{font-size:1rem;margin-top:2rem;border-bottom:1px solid #2a2f3a;padding-bottom:.3rem}table{border-collapse:collapse;width:100%;font-size:.85rem}td,th{text-align:left;padding:.3rem .8rem .3rem 0;border-bottom:1px solid #1d212a;vertical-align:top}th{color:#8b93a3;font-weight:normal}a{color:#7ab7ff;text-decoration:none}a:hover{text-decoration:underline}small,.dim{color:#737b8c}</style></head><body><h1>dist — release console</h1>";
+
+INDEX_FOOT :: "<p class=\"dim\"><small>API: <a href=\"/api/apps\">/api/apps</a> &middot; <a href=\"/healthz\">/healthz</a></small></p></body></html>";
+
+// Server-rendered index: every app with its channels and its releases'
+// artifacts as direct /download links. Dense and read-only, per the
+// product shape — the full admin UI is subplan 06.
+render_index :: (repo: *Repo) -> string {
+    page := INDEX_HEAD;
+    if repo.apps.len == 0 {
+        page = concat(page, "<p class=\"dim\">nothing published yet</p>");
+    }
+    a := 0;
+    while a < repo.apps.len {
+        app := repo.apps.items[a];
+        page = concat(page, concat("<h2>", concat(html_escape(app.slug), concat(" <small>", concat(html_escape(app.display_name), "</small></h2>")))));
+
+        // Channels: name -> current release pointer.
+        page = concat(page, "<table><tr><th>channel</th><th>current release</th></tr>");
+        c := 0;
+        while c < repo.channels.len {
+            ch := repo.channels.items[c];
+            if ch.app_id == app.id {
+                page = concat(page, concat("<tr><td>", concat(html_escape(ch.name), concat("</td><td>", concat(html_escape(ch.current_release_id), "</td></tr>")))));
+            }
+            c += 1;
+        }
+        page = concat(page, "</table>");
+
+        // Releases with their artifacts as download links.
+        page = concat(page, "<table><tr><th>release</th><th>platform</th><th>artifact</th><th>size</th><th>sha256</th></tr>");
+        r := 0;
+        while r < repo.releases.len {
+            rel := repo.releases.items[r];
+            if rel.app_id == app.id {
+                k := 0;
+                while k < repo.artifacts.len {
+                    art := repo.artifacts.items[k];
+                    if art.release_id == rel.id {
+                        row := concat("<tr><td>", concat(html_escape(rel.version), concat(" <small>", concat(html_escape(rel.id), "</small></td><td>"))));
+                        row = concat(row, concat(db.platform_str(art.platform), "</td><td>"));
+                        row = concat(row, concat("<a href=\"/download/", concat(art.sha256, concat("\">", concat(html_escape(art.filename), "</a></td><td>")))));
+                        row = concat(row, concat(int_to_string(art.size_bytes), "</td><td><small>"));
+                        row = concat(row, concat(short_sha(art.sha256), "&hellip;</small></td></tr>"));
+                        page = concat(page, row);
+                    }
+                    k += 1;
+                }
+            }
+            r += 1;
+        }
+        page = concat(page, "</table>");
+        a += 1;
+    }
+    return concat(page, INDEX_FOOT);
+}
+
+handle_index :: (client: s32, store_dir: string) {
+    rq := load_or_503(client, store_dir);
+    if rq == null { return; }
+    repo := rq!;
+    http.respond(client, 200, "text/html; charset=utf-8", "", render_index(@repo));
+}
+
 // ── routes ────────────────────────────────────────────────────────────
 
 handle_apps_index :: (client: s32, store_dir: string) {
@@ -235,6 +333,10 @@ route :: (client: s32, store_dir: string, method: string, path: string) -> s64 {
             "every distd route is GET for now (writes go through the dist CLI)");
         return 405;
     }
+    if path == "/" {
+        handle_index(client, store_dir);
+        return 200;
+    }
     if path == "/healthz" {
         http.respond(client, 200, "application/json", "", "{\"status\":\"ok\"}");
         return 200;

tests/server_http.sx

@@ -5,6 +5,8 @@
 // `build/dist server run` on a test port in the background, waits for
 // /healthz, and asserts every route against curl:
 //
+//   * /                       → HTML index naming the app, with a
+//                               /download/<sha> link
 //   * /healthz                → {"status":"ok"}
 //   * /api/apps               → the published app is listed
 //   * /api/apps/<slug>        → app + its releases + channels
@@ -48,6 +50,24 @@ write_file :: (path: string, body: string) {
     process.run(cmd);
 }
 
+// True iff `needle` occurs in `hay` (plain scan; bodies are small).
+contains :: (hay: string, needle: string) -> bool {
+    if needle.len == 0 { return true; }
+    if needle.len > hay.len { return false; }
+    i := 0;
+    while i + needle.len <= hay.len {
+        j := 0;
+        ok := true;
+        while j < needle.len {
+            if hay[i + j] != needle[j] { ok = false; break; }
+            j += 1;
+        }
+        if ok { return true; }
+        i += 1;
+    }
+    return false;
+}
+
 // GET `path` and return the body (curl; 2s timeout so a dead server fails
 // the test instead of hanging it).
 fetch :: (path: string) -> string {
@@ -113,6 +133,12 @@ main :: () -> s32 {
     print("  server up\n");
 
     // ── routes ────────────────────────────────────────────────────────
+    process.assert(fetch_code("/") == "200", "/ serves the HTML index");
+    idx := fetch("/");
+    process.assert(contains(idx, "<title>dist</title>"), "index is the dist HTML page");
+    process.assert(contains(idx, "acme-app"), "index names the published app");
+    process.assert(contains(idx, "/download/"), "index links artifact downloads");
+
     hz := parse_body(fetch("/healthz"), "/healthz", xx arena);
     process.assert(get_str(hz, "status") == "ok", "/healthz status ok");