feat(framework): HTTP/1.1 parse + serialize + serve loop (iter 16 Task 2)

- http/parse.wo: bounded-read buffering to the header terminator, then
  exactly Content-Length body bytes; %XX decoding ('+' = space in query
  strings only, malformed escapes pass through — parsing stays total);
  path/query split with decoded pairs; header names lowercased; the
  three-state Parsed record (closed / malformed / request) with keep-alive
  carry-over — bytes past this request belong to the next one on the
  connection.
- http/serve.wo: Dispatcher interface (the router's seam), status/reason
  serialization with computed Content-Length, and the blocking loop:
  malformed -> 400 + close; a trapping handler -> 500 AND the loop lives;
  fds closed on every path; env.stopping() honored.
- Connection policy discovered by probing, not assumed: a parked keep-alive
  connection BLOCKS accept on a single-threaded server (probe: client 1
  idles open, client 2 starves). Policy: serve PIPELINED requests on one
  connection (carry non-empty), close when the client would idle; a proxy
  reconnects. README states it.

Verified against a throwaway echo app (not committed): %20 query decode;
two pipelined requests -> two responses on one connection; DIV0 handler ->
500 and the NEXT connection served; GARBAGE -> 400; SIGTERM stops clean.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/examples/writeonce-framework/README.md

@@ -10,10 +10,15 @@ writeonce-framework = { git = "https://github.com/shoneyj/writeonce-framework",
 
 ## What it is
 
-- **HTTP/1.1 keep-alive** server core (`http/`): request parsing
-  (`Content-Length` bodies), response serialization, a blocking serve loop
-  that answers 400 to malformed requests, 500 to trapping handlers (and
-  survives), closes every fd, and honors SIGTERM.
+- **HTTP/1.1** server core (`http/`): request parsing (`Content-Length`
+  bodies, %-decoded paths and query strings), response serialization, a
+  blocking serve loop that answers 400 to malformed requests, 500 to
+  trapping handlers (and survives), closes every fd, and honors SIGTERM.
+  Connection policy: **pipelined requests are served on one connection;
+  idle connections close after the response** — on a single-threaded server
+  a parked keep-alive connection would block `accept` and starve every
+  other client, so closing is the correct shape until shards/fibers (8/11).
+  A proxy in front simply reconnects.
 - **Router** (`router/`): method + path table with `:param` captures into
   `req.params`; first match wins; no match is the framework's 404.
 - **Handlers without closures**: the language has no function values by

docs/examples/writeonce-framework/http/parse.wo

@@ -0,0 +1,148 @@
+-- http/parse.wo — HTTP/1.1 request parsing over a net connection.
+--
+-- Bounded reads only (`net.read`), so requests are buffered to the header
+-- terminator, then the body to exactly Content-Length. Keep-alive means
+-- bytes past this request belong to the NEXT one: the caller passes the
+-- carry-over in and gets the new remainder back in Parsed.rest.
+--
+-- Parsed is a three-state answer (no tuples in the language):
+--   closed=true            peer ended the connection cleanly between requests
+--   ok=false               malformed request — answer 400 and close
+--   ok=true, req non-nil   one complete request
+use net
+
+const BODY_MAX = 1048576
+
+pub typedef Parsed = {
+  closed: Bool,
+  ok:     Bool,
+  ?req:   Req,
+  rest:   Text
+}
+
+-- %XX decoding, '+' as space when plus_space (query strings only).
+-- Malformed escapes pass through verbatim — parsing stays total.
+fn hex_val(b: Int) -> Int {
+  if b >= 48 and b <= 57 { return b - 48; }        -- 0-9
+  if b >= 97 and b <= 102 { return b - 87; }       -- a-f
+  if b >= 65 and b <= 70 { return b - 55; }        -- A-F
+  return -1;
+}
+
+pub fn url_decode(t: Text, plus_space: Bool) -> Text {
+  let out = "";
+  let i = 0;
+  let n = len(t);
+  while i < n {
+    let b = byte_at(t, i);
+    if b == 37 and i + 2 < n {                     -- '%'
+      let hi = hex_val(byte_at(t, i + 1));
+      let lo = hex_val(byte_at(t, i + 2));
+      if hi >= 0 and lo >= 0 {
+        out = out .. char_of(hi * 16 + lo);
+        i = i + 3;
+        continue;
+      }
+    }
+    if plus_space and b == 43 {                    -- '+'
+      out = out .. " ";
+      i = i + 1;
+      continue;
+    }
+    out = out .. substr(t, i, 1);
+    i = i + 1;
+  }
+  return out;
+}
+
+-- "a=1&b=hello+world" -> decoded pairs; a bare key maps to ""
+fn parse_query(qs: Text) -> map<Text, Text> {
+  let q: map<Text, Text> = {};
+  if qs == "" { return q; }
+  for pair in split(qs, "&") {
+    if pair == "" { continue; }
+    let eq = index_of(pair, "=");
+    if eq < 0 {
+      q[url_decode(pair, true)] = "";
+    } else {
+      q[url_decode(substr(pair, 0, eq), true)] = url_decode(substr(pair, eq + 1, len(pair) - eq - 1), true);
+    }
+  }
+  return q;
+}
+
+fn malformed(rest: Text) -> Parsed {
+  return Parsed { closed: false, ok: false, req: nil, rest: rest };
+}
+
+-- One request off the connection. `carry` = leftover bytes from the same
+-- connection's previous request (keep-alive).
+pub fn parse_request(c: net.Conn, carry: Text) -> Parsed {
+  let buf = carry;
+  let header_end = index_of(buf, "\r\n\r\n");
+  while header_end == -1 {
+    let got = net.read(c, 8192);
+    if len(got) == 0 {
+      -- peer closed: clean between requests (empty buffer), torn otherwise
+      if trim(buf) == "" { return Parsed { closed: true, ok: true, req: nil, rest: "" }; }
+      return malformed("");
+    }
+    buf = buf .. got;
+    header_end = index_of(buf, "\r\n\r\n");
+    if header_end == -1 and len(buf) > BODY_MAX { return malformed(""); }
+  }
+
+  let lines = split(substr(buf, 0, header_end), "\r\n");
+  let req_line = split_ws(trim(lines[0]));
+  if len(req_line) < 3 { return malformed(""); }
+  let method = req_line[0];
+  let target = req_line[1];
+
+  -- path / query split, both %-decoded ('+' is a space only in the query)
+  let path = target;
+  let query: map<Text, Text> = {};
+  let qm = index_of(target, "?");
+  if qm >= 0 {
+    path = substr(target, 0, qm);
+    query = parse_query(substr(target, qm + 1, len(target) - qm - 1));
+  }
+  path = url_decode(path, false);
+
+  let headers: map<Text, Text> = {};
+  let i = 1;
+  while i < len(lines) {
+    let line = trim(lines[i]);
+    i = i + 1;
+    if line == "" { continue; }
+    let colon = index_of(line, ":");
+    if colon > 0 {
+      headers[to_lower(substr(line, 0, colon))] = trim(substr(line, colon + 1, len(line) - colon - 1));
+    }
+  }
+
+  let want = 0;
+  let cl = headers["content-length"];
+  if cl != nil {
+    let n = parse_int(cl);
+    if n == nil { return malformed(""); }
+    if n < 0 or n > BODY_MAX { return malformed(""); }
+    want = n;
+  }
+
+  let body = substr(buf, header_end + 4, len(buf) - header_end - 4);
+  while len(body) < want {
+    let got = net.read(c, 8192);
+    if len(got) == 0 { return malformed(""); }     -- peer died mid-body
+    body = body .. got;
+  }
+  -- bytes past the declared body belong to the next request on this conn
+  let rest = "";
+  if len(body) > want {
+    rest = substr(body, want, len(body) - want);
+    body = substr(body, 0, want);
+  }
+
+  let req = Req { method: method, path: path, params: {}, query: query,
+                  headers: headers, body: body };
+  return Parsed { closed: false, ok: true, req: req, rest: rest };
+}

docs/examples/writeonce-framework/http/serve.wo

@@ -0,0 +1,80 @@
+-- http/serve.wo — response serialization + the blocking keep-alive serve
+-- loop. The dispatch seam is the Dispatcher interface (the router's App
+-- satisfies it, Task 3); it is wrapped in `try`, so a trapping handler
+-- answers 500 and the loop lives — a bad request must never kill the
+-- server. Every accept path closes its fd; `env.stopping()` is honored
+-- between connections and between keep-alive requests (a SIGTERM landing
+-- in a blocking call already unwinds cleanly — the runtime's stop story).
+use net
+use env
+
+pub interface Dispatcher {
+  fn dispatch(req: Req) -> Resp
+}
+
+fn status_text(code: Int) -> Text {
+  switch code {
+    case 200: return "OK";
+    case 201: return "Created";
+    case 302: return "Found";
+    case 400: return "Bad Request";
+    case 401: return "Unauthorized";
+    case 404: return "Not Found";
+    case 409: return "Conflict";
+    case 500: return "Internal Server Error";
+    default:  return "Status";
+  }
+}
+
+pub fn serialize(resp: Resp, keep: Bool) -> Text {
+  let head = "HTTP/1.1 ${resp.status} ${status_text(resp.status)}\r\n";
+  for k, v in resp.headers {
+    head = head .. "${k}: ${v}\r\n";
+  }
+  if keep {
+    head = head .. "Connection: keep-alive\r\n";
+  } else {
+    head = head .. "Connection: close\r\n";
+  }
+  head = head .. "Content-Length: ${len(resp.body)}\r\n\r\n";
+  return head .. resp.body;
+}
+
+pub fn serve(host: Text, port: Int, d: Dispatcher) -> Int {
+  let srv = net.listen(host, port);
+  print("listening on ${host}:${port}");
+  while true {
+    if env.stopping() { net.close(srv); return 0; }
+    let c = net.accept(srv);
+    let carry = "";
+    let alive = true;
+    while alive {
+      if env.stopping() { alive = false; continue; }
+      let p = try parse_request(c, carry) catch (e) nil;   -- an IO trap = gone
+      if p == nil { alive = false; continue; }
+      if p.closed { alive = false; continue; }
+      if p.ok == false {
+        try net.write(c, serialize(bad_request("malformed request"), false)) catch (e) {}
+        alive = false;
+        continue;
+      }
+      let r = p.req;
+      if r == nil { alive = false; continue; }
+      carry = p.rest;
+      -- Connection policy for a single-threaded server: serve PIPELINED
+      -- requests on one connection (bytes already buffered), but close when
+      -- the client would idle — a parked keep-alive connection would block
+      -- `accept` and starve every other client. A proxy in front simply
+      -- reconnects; this is the honest shape until shards/fibers (8/11).
+      let keep = len(carry) > 0;
+      let conn = r.headers["connection"];
+      if conn != nil {
+        if to_lower(conn) == "close" { keep = false; }
+      }
+      let resp = try d.dispatch(r) catch (e) server_error();
+      try net.write(c, serialize(resp, keep)) catch (e) { alive = false; }
+      if keep == false { alive = false; }
+    }
+    net.close(c);
+  }
+}