writeonce/docs/stories/language-runtime-database/39-web-framework-parity.md

iteration	status
39	refine

Iteration 39 — web framework parity: randomness, cookies, and the store-backed middleware chain

Format: product/story-iteration-template. Part of Story — one language, one runtime, one database, one binary.

Inserted 2026-08-26 (developer ask: add gofiber/fiber as a reference and find the basic features the web framework lacks). Derived from the Fiber v3.5.0 parity study, which read Fiber's routing surface, Req/Res API, binder and all 32 of its middleware/ packages against docs/examples/porch. This iteration takes that study's §0–§2 plus the cheap half of §5; the study names an owner for everything it leaves out.

Goals

• A random-bytes builtin, first, because it gates the rest. The framework README's crypto row claims signed cookies, CSRF and session integrity are "UNBLOCKED — the primitives exist since iteration 34". For CSRF and sessions that is wrong: SHA-256 and HMAC let a program authenticate a token, not mint one, and writeonce has no source of randomness anywhere — no getrandom(2), no CSPRNG builtin, nothing. An HMAC over a guessable session id is a signed guess. Close this before writing a line of session code, and correct the ledger row that says otherwise.
• Cookies, in both directions. Absent entirely today: nothing parses a Cookie: request header and there is no Set-Cookie builder. This is the foundation the next goal stands on, and it forces a design decision the framework has so far avoided — Resp.headers is a map<Text, Text>, so it structurally cannot carry the two Set-Cookie lines a login-plus-flash response needs. Deciding what replaces or supplements that map is the real work of this goal; the parsing is the easy half.
• The store-backed middleware chain, in dependency order: rate limiting and idempotency first (they need only a store and time.ticks, both of which exist — the cheapest real wins available), then sessions, then CSRF. Each is an ordinary .wo middleware class, and each gets a durable store for free from @table — where Fiber ships an in-memory default and expects you to bolt on Redis. That is a genuine writeonce advantage and the samples should show it.
• Close the routing and response sugar that is merely missing. PATCH / OPTIONS / HEAD / ALL registration helpers (a Route { method: "PATCH" } literal already works, so this is registration ergonomics), a per-route body limit instead of one compile-time BODY_MAX = 1048576 for the whole server, a request-id middleware, and the response helpers every framework has and this one writes by hand: Location, Vary, Attachment/Download.
• Say what is still missing, with an owner. The study's §3–§6 stay out of scope; this iteration's closing act is updating the framework README's ledger so each row points at whoever owns it rather than reading as an oversight.

Acceptance Criteria

• Given the random-bytes builtin, when the acceptance script draws many values across separate processes, then no value repeats and none is derivable from the clock — and the builtin is refused, loudly, if the kernel source is unavailable rather than silently falling back to something weaker. A CSPRNG that degrades quietly is worse than no CSPRNG.
• Given a login handler that sets a session cookie and a flash cookie on one response, when the response is serialized, then two distinct Set-Cookie headers reach the wire — the criterion the current map<Text, Text> cannot satisfy, and the reason this iteration touches Resp.
• Given a request carrying a Cookie: header with several pairs, quoted values and stray whitespace, when it is parsed, then each value is recovered exactly, and a malformed header is a 400 rather than a silent partial parse.
• Given a session cookie whose HMAC is altered by one bit, when the session middleware reads it, then the session is rejected in constant time (ct_eq, which already exists) and the request proceeds unauthenticated — never as a different user.
• Given the limiter configured to N requests per window, when a client exceeds it, then it receives 429 with the rate-limit headers set, the window expires on time.ticks, and the counters survive a restart — the durability the @table store buys, proven by a restart in the gate.
• Given a CSRF-protected form flow, when a request arrives with a missing, stale or foreign-origin token, then each is refused distinctly; when the token is valid, the request proceeds. Single-use tokens are not double-spendable.
• Given the same POST replayed with an identical idempotency key, when it is handled, then the stored response is returned and the handler does not run twice — proven by a side effect that would be visible if it had.
• Given a route registered with each new method helper and a per-route body limit, when the matrix runs, then methods dispatch correctly, an oversized body is refused per-route rather than per-server, and every standing gate (just web-app, just site, oop-accept) is unchanged.

Out Of Scope

Every item below is a real Fiber feature and a real writeonce gap. Each is excluded because someone else owns it — the study's §7 is the full map.

• Streaming, SSE, compression, byte-range requests — all four sit on one missing seam: internal/serve.wo builds a whole response as one Text and serialize() always emits Content-Length. The framework README already parks "lazy body streaming + backpressure · streaming responses · explicit commit point"; these belong to that slice. Note internal/parse.wo:153-157 deliberately refuses chunked request bodies with a request-smuggling note — that refusal is correct and must survive whoever implements chunked.
• Typed binding of query / params / form / headers into a class — Fiber's Bind reflects over struct tags; principle 13 forbids reflection, so the answer is compile-time generation: iteration 29's @derive. Recorded, not attempted. Same for XML/CBOR/MsgPack codecs — JSON only is the small stdlib working as intended.
• TTL cache middleware — iteration 18 owns it, spec already approved.
• proxy middleware — needs an outbound socket, which does not exist: iteration 38.
• pprof / expvar / metrics / stack traces on trap — iteration 30 (observability, CI, fuzz — still no story file).
• Everything the study's §6 lists as a deliberate divergence: a runtime template engine (markup is a compile-time literal or it does not exist), TLS and HTTP/2 (proxy-terminated by doctrine), net/http interop (no FFI), prefork and buffer-size knobs (the shard runtime owns placement), closures as handlers (a handler is a class; its fields are the closure substitute). These are settled — the study lists them so nobody re-opens them as "missing".
• A radix-tree router. Path matching is a linear scan, already 🔶 in the ledger pending a measurement. Iteration 22 built the harness but benched the database, not the router. Still waiting on a number, not on this iteration.

Info

Fiber v3.5.0, .dev/reference/fiber (gitignored; the study carries the clone command). Of its 32 middleware packages, nine already have a working porch counterpart — CORS, basic auth, key/bearer auth, helmet-style security headers, ETag, static files, logger, host authorization, and recover-as-500. The framework is further along than its size suggests; the gaps are breadth, not foundations, with the single exception of randomness.

Dependency order, which is the whole point of the iteration:

random bytes  ──▶  cookies  ──▶  sessions  ──▶  CSRF
     │                 │
     │                 └──▶  (signed cookies, JWT HS256 issuing)
     └──▶  request-id

limiter, idempotency  ──▶  need only @table + time.ticks (start here)

Forks the spec must settle:

1. What replaces Resp.headers: map<Text, Text>? Options: a multi Text of raw header lines beside the map; a dedicated cookies: multi Cookie field on Resp that serialize() renders; or a general repeated-header list. The first is smallest, the second is the most typed, the third is the most honest about HTTP. This fork decides how much of the framework's public surface moves, so it comes first.
2. What shape is the random builtin? random_bytes(n) -> Bytes is the obvious one and composes with everything iteration 19 and 34 added. Decide whether a convenience random_hex/random_id rides along or whether base64_encode is enough, and decide the failure mode when the kernel source is unavailable — the criterion above says refuse, not degrade.
3. Is there a Store interface, or does each middleware own its @table? Fiber abstracts Storage so the same middleware runs on memory or Redis. writeonce has one store, and interfaces are structural — an abstraction with exactly one implementor is decoration (iteration 37 learned this the hard way about Component). Leaning: concrete @table per middleware until a second backend actually exists.
4. Where does session state live — cookie or table? A signed cookie carrying the whole payload needs no store and cannot be revoked; a table row keyed by a random id can be revoked and costs a lookup. Leaning: table, since @table is the language's whole thesis and revocation is not optional for a real login.
5. Does the request-id middleware trust an inbound header? Fiber's requestid accepts one by default. Behind a trusted proxy that is what you want; on an open port it lets a client forge correlation ids. client_ip and net.peer already exist for the trust decision — reuse that judgement rather than inventing a second one.

Proposed Solution

Wants a spec: fork 1 changes public framework types, and fork 2 adds a runtime builtin. Order follows the dependency chain above, and the first slice is deliberately the cheapest rather than the most foundational — limiter and idempotency need nothing new, so they prove the store pattern and the gate shape before the risky work starts.

Then: the random builtin (runtime, with its own corpus fixtures), cookies (the Resp decision plus parse and serialize), sessions, CSRF, and the routing and response sugar last since it is independent of everything else. Each slice ends green on just web-app and just site, and the closing act corrects the framework README's crypto row and re-points every ledger row this study touched at its actual owner.

Off-chain and independent of the concurrency chain, with one caveat worth stating: the SSE work this study defers is a natural companion to iteration 24's chat sample, since a room actor already has the fan-out shape. If 24 lands first, SSE gets cheaper.