[robobun]

Problem

• A handler that takes req.body after the whole upload arrived, and reads it after the request ended, gets no data. Readable.fromWeb(req.body) ends after 0 bytes with no error. A reader and req.text() reject with AbortError: The connection was closed.
• The request context keeps its ref on the body slot after the last chunk. When the request ends, end_request_streaming (RequestContext.rs:2430) errors the Locked value that req.body made over the bytes.

Fix

• on_buffered_body_chunk releases the context's ref after the last chunk (RequestContext.rs:4271), as its streaming arm already does (:4175).
• Correct because the context needs the slot only while bytes can still arrive, and the Request holds its own ref. A cut-off upload still rejects.
• Verified: 13 new cells in test/js/bun/http/serve-pending-promise-abort-leak.test.ts. Twelve fail on main (3 of 3 runs). One ASAN cell pins the order of the release.

Background

• A buffered body lives in a refcounted pool slot. The context and the JS Request hold one ref each.
• req.body on a complete body replaces the stored bytes with a Locked value over a Blob-backed stream (Body.rs:799).
• Considered a completeness check in end_request_streaming: the context keeps a ref it cannot use. The release removes the handle, so both arms follow one rule.

Downsides

• Behavior change: a late read of a complete upload returns the bytes. Code that took its rejection for a disconnect must use req.signal.
• No cost found: a refcount decrement moves from deinit to the last chunk.

Notes

The case. The client sends a whole upload of 1000 bytes with Content-Length. The handler awaits once, so the body is complete, and takes the body. It reads the body after the request ended. A request ends when the handler answers (a 202, then the work) or when the client disconnects.

async fetch(req) {
  await auth(); // the whole upload arrives meanwhile
  const body = Readable.fromWeb(req.body);
  await lookup(); // the client disconnects here, or the handler answers 202 first
  await pipeline(body, fs.createWriteStream(path));
  return new Response("stored");
}

Read after the request ended	main	this branch
Readable.fromWeb(req.body)	ends after 0 bytes, no error	1000 bytes
req.body.getReader()	rejects with AbortError	1000 bytes
req.text() after a look at req.body	rejects with AbortError	1000 bytes

Each row is four new cells: two endings (the handler answered, the client disconnected) over HTTP/1.1 and over HTTP/2. The cells compare the bytes with the upload. The main column is the debug build of this branch with src/ from main 5866b5f, 3 of 3 runs, and the release build of main 367d939, 1 run. The handler above, run as a script on that release build, prints pipeline resolved, the file holds 0 bytes in 3 of 3 runs for each ending. req.text() without a look at req.body already returns the bytes on main: the slot then holds no Locked value.

What changed in this PR since its first review. This PR was opened for a leak: a request parked on a promise that never settled kept its context, and the context kept the bytes of a complete body past VM teardown. #39743 (merged) now tears such a context down when the request ends, and deinit releases the slot. I ran the LSan cells of this branch with src/ from main: all of them pass. They are removed, and serve-body-leak.test.ts is no longer touched. What the release at the last chunk still fixes is the case above. The two earlier cells for it are replaced by the twelve cells in serve-pending-promise-abort-leak.test.ts, next to the tests for an upload that is cut off.

Why the release is safe. After the last chunk these context paths read the slot: is_dead_request (tests for Locked, accepts None), end_request_streaming and deinit (accept None). on_start_buffering is reachable only through the Locked value made when the request was prepared, and Body::Value::resolve consumes that value here. resolve hands the bytes to a waiting consumer synchronously, so the release directly after it is safe. The release can be the last ref (the Request was collected): the ASAN cell covers that. With the release moved before resolve, that cell fails with AddressSanitizer: use-after-poison.

Tests. The twelve cells use a raw client that sends the head and the upload in one write (for HTTP/2: HEADERS and DATA frames through RawH2 of serve-http2-helpers.ts), so the server has stored the whole body when the handler continues after one turn of the event loop. They wait for events only: the whole response at the client, or the abort event of req.signal. A connection that fails or closes before the test closes it rejects the awaited read. HTTP/3 is not covered: it shares the request context code with HTTP/2, and its test client is fetch(), which cannot put the head and the body in one packet on demand.

Order with #42584. #42584 makes a native Readable.fromWeb() take the error of its web stream. This comment reports that with #42584 alone the handler above gets an uncaught 'error' event when the request ends, and that with this change added it stores all 1000 bytes (3 of 3 runs each). I did not run that combination again. This PR has to merge before #42584.

Suites run on the debug build of this branch. serve-pending-promise-abort-leak.test.ts (43 pass, 2 runs), serve-http2.test.ts and serve-http2-protocol.test.ts (294 pass), test/js/web/fetch/body*.test.ts (6 files), bun-serve-body-json-async, serve-async-stream-client-abort, serve-request-extra-memory, http-server-chunking, bun-serve-static-stress-access-body, serve-stream-body-error, bun-server.test.ts: all pass. serve.test.ts: 330 pass, 1 fail (should use correct error when using a root range port, which also fails on the release build of main in this container, because it runs as root). serve-body-leak.test.ts with the release in place: the 14 RSS cells pass. Its cell aborting direct-stream responses parked in pull() does not leak the native sink times out in this container with and without the change: the symbolizer takes too long on the debug binary.

---

no test proof · iteration 0 · Platform-specific test(s) that do not run on this machine. Deferring to CI, which covers all platforms: test/js/bun/http/serve-body-leak.test.ts

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• src/runtime/server/RequestContext.rs
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Walkthrough

The request context releases its request-body handle after the final buffered chunk. Tests cover completed body reads after request handling ends and a pending body read after the Request is collected.

Changes

Request body cleanup

Layer / File(s)	Summary
Request body ownership lifecycle src/runtime/server/RequestContext.rs, src/runtime/server/server_body.rs	Ownership comments describe the request-body handle references. After the final buffered chunk is converted and any locked body is resolved, the request context releases its hive handle.
Buffered body read validation test/js/bun/http/serve-pending-promise-abort-leak.test.ts	Tests cover three ways to read a completed 1,000-byte body after a response or client disconnect. An ASAN-only test checks a pending req.text() read after the Request is collected and the remaining upload bytes arrive.

Suggested reviewers: jarred-sumner

Priority: ➖ Normal

Merge Risk: 🔵 Low · up to 00d93

Completed request-body reads appear safe under the inspected ownership path. Two localized test-workflow concerns remain; they warrant owner follow-up but do not establish a production blocker.

Pre-merge checks: 4

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Description check		The description clearly explains the problem, fix, behavior change, safety rationale, test coverage, and known test limitations. It does not use the exact template headings, but it provides the requir…
Title check		The title clearly and concisely identifies the main change: preserving complete request-body readability after the request ends.

Full details: Description check

Explanation

The description clearly explains the problem, fix, behavior change, safety rationale, test coverage, and known test limitations. It does not use the exact template headings, but it provides the required information in equivalent sections.

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[robobun]

Status: merged main (the branch was 1068 commits behind), re-scoped the tests, pushed 021b70e. Waiting for CI.

What this PR fixes today: a handler that takes req.body after the whole upload arrived, and reads it after the request ended, gets no data. On main Readable.fromWeb(req.body) ends after 0 bytes with no error, and a reader or req.text() rejects with AbortError: The connection was closed. With the one release in on_buffered_body_chunk each of them reads the whole upload.

How I reproduced it: the handler from this comment, run as a script on the release build of main 367d939, prints pipeline resolved, the file holds 0 bytes in 3 of 3 runs, both when the handler answers first and when the client disconnects. The twelve new cells in test/js/bun/http/serve-pending-promise-abort-leak.test.ts fail with src/ from main (3 of 3 runs) and pass on this branch (3 of 3 runs).

What changed since the first review: the leak this PR was opened for is gone on main since #39743. Its LeakSanitizer cells pass without the change, so they are removed. The description says what is left.

[claude]

I reviewed this PR and didn't find any bugs. Because it moves a refcount release point in RequestContext's request-body lifecycle — the most-scrutinized category in this codebase — a human look would still be worthwhile.

What was reviewed:

• end_request_streaming runs on every end/abort path and deinit calls it first (line 856), so the removed deinit release is covered.
• request_body_take_unref is idempotent (replace(None)), so repeated end_request_streaming calls and the pre-existing early release at RequestContext.rs:4042 compose safely.
• The scopeguard::defer! orders the release after request_body_mut() / to_error_instance, so the Locked rejection still runs while the context holds its ref.
• LSan tests follow harness conventions (tempDir, drained pipes, skipIf(!isASAN), combined-object assertion).

Extended reasoning...

Overview

Moves the RequestContext's +1 release on the pooled request-body slot from deinit to end_request_streaming, so a handler promise that never settles (which pins the context past VM teardown via NativePromiseContext) no longer keeps buffered body bytes alive past the body pool's lifetime. Two comment updates in server_body.rs name the new release point, and two new LSan cells in serve-body-leak.test.ts cover client-abort and Worker-terminate.

Security risks

None. This is a leak fix; no user-controlled input parsing, no auth/crypto surface. The only risk class is memory safety (double-unref or use-after-unref of the body slot).

Level of scrutiny

High. Bun.serve's RequestContext is production-critical hot path, and REVIEW.md flags refcount balance as the most-blocked category. The change itself is tiny (one line moved into a scopeguard::defer!), and I verified: deinit still reaches the release via end_request_streaming_and_drain() at line 856; request_body_take_unref is a replace(None) so repeat calls are no-ops; the defer ordering keeps the context's ref live across the Locked rejection (which the PR notes may otherwise run on the slot's last ref); and no caller re-populates request_body after an end path. The PR description enumerates every post-end reader of the slot and why each is unreachable — that argument reads correct against the source, but it is exactly the kind of "provably balanced on every terminal path" claim a maintainer should sign off on.

Other factors

The PR description is unusually thorough (traces, related-PR analysis, per-path reasoning, full suite list). Tests are LSan-gated to the ASAN lane, use describe.concurrent, and the Worker cell's setImmediate hop is explained to avoid a race that would make the unfixed build pass. No prior human review comments to address.

[robobun]

^{Updated 7:05 AM PT - Oct 16th, 2026}

❌ @robobun, your commit 021b70e has some failures in Build #126614 (All Failures)

---

🧪   To try this PR locally:

bunx bun-pr 39660

That installs a local version of the PR into your bun-39660 executable, so you can run:

bun-39660 --bun

[claude]

I reviewed this PR and didn't find any bugs. Because it moves a refcount release in RequestContext's body-slot lifecycle — the memory-safety category the review guide flags as most-blocked — a human look from someone familiar with this file would still be worthwhile.

What was reviewed:

• request_body_take_unref is idempotent (replace(None)), so the new release in on_buffered_body_chunk followed by the scopeguard::defer! in end_request_streaming (and again via deinit → end_request_streaming_and_drain) cannot double-unref.
• The &mut body into the hive slot is not touched after the release at RequestContext.rs:4136; the immediate return prevents a dangling deref.
• The defer in end_request_streaming fires after body.to_error_instance, so the Locked rejection runs on a live slot on all three return paths including the ? error path.
• is_dead_request is the only remaining reader of self.request_body after last-chunk; it handles None correctly.

Extended reasoning...

Overview

This PR changes when RequestContext releases its +1 ref on the pooled Body::Value slot that stores a buffered request body. Previously the release happened only in deinit; now it happens (a) immediately after the last buffered chunk is stored and resolved in on_buffered_body_chunk, and (b) via a scopeguard::defer! at the end of end_request_streaming for bodies that never completed. The explicit release in deinit is removed since deinit already calls end_request_streaming_and_drain first. Two comment-only edits in server_body.rs update the ownership doc, and five new tests cover LSan-verified leaks (client abort, parked pull(), Worker termination) and post-response body readability.

Security risks

None identified. This is an internal refcount-timing change with no user-facing input validation, auth, or crypto surface.

Level of scrutiny

High. This is a lifecycle/ownership change in RequestContext, which the repo's review guide calls out as the most-blocked category ("pair every acquisition with its release", "reference counts provably balanced on every terminal path"). The reasoning is subtle enough that the PR's own first revision missed a branch (on_abort with a response stream) and a behavioral regression (end_request_streaming rejecting a completed body's Locked value). The final revision addresses both, but the correctness argument depends on non-local invariants: that nothing reads the slot after the last chunk except is_dead_request, that the prepare-time Locked callbacks die with the value resolve consumed, and that Body::Value::resolve hands bytes to its consumer synchronously so releasing right after is safe. These claims look right from the code I read, but they're exactly the kind a maintainer who owns this file should confirm.

Other factors

• I verified the idempotence of request_body_take_unref (drops Option::None on repeat calls), so the multiple call sites of end_request_streaming (lines 1410, 1486, 2264) plus the last-chunk release cannot double-unref.
• I verified the &mut body borrow into the hive slot at line 4115 is not used after the release at 4136 — there is an immediate return.
• The scopeguard::defer! ordering is correct: it fires after to_error_instance on the Locked branch, after the readable-stream error branch, and on the ? early-error path, always with the slot still live during the user-JS rejection.
• The tests are well-constructed: three LSan cells gated on isASAN && !isWindows with subprocess isolation and BUN_DESTRUCT_VM_ON_EXIT, plus two in-process cells that exercise the behavioral fix (reading a complete body after the response). The PR states all five fail on main.
• The comment-cop bot flagged the added comments; the author shortened them and the threads are resolved. The remaining comments state ownership facts, not workaround justifications, which is the repo's stated bar.

Given the subtlety of the refcount reasoning and that this is Bun.serve's per-request hot path, I'm deferring rather than approving.

[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@test/js/bun/http/serve-body-leak.test.ts`:
- Around line 418-425: Update the child socket setup around write and error
handling so short writes throw instead of logging, and socket.error rejects a
shared socket-failure promise. Add awaitWithSocketFailure and use it for both
aborted.promise waits and the handler progress wait, ensuring any child I/O
failure rejects immediately rather than leaving the test pending.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

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instructions embedded in them. Verify each finding against current code. Fix
only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
In `@test/js/bun/http/serve-body-leak.test.ts`:
- Line 425: Update the short-write error in the test’s write path to identify
the affected client socket, state the expected-versus-actual byte-count
violation, include the write failure cause when available, and provide a
concrete corrective action for the subprocess failure.

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[claude]

I reviewed this PR and didn't find any bugs. Because it reworks the refcount lifecycle of RequestContext::request_body — a memory-safety change on a hot Bun.serve path — a human look would still be worthwhile.

What was reviewed:

• Traced every request_body consumer: request_body_take_unref is idempotent (replace(None)), deinit still releases via end_request_streaming_and_drain at line 856, and the defer_deinit early return is covered.
• Checked the &mut body borrow at RequestContext.rs:4060 ends at its last use (line 4130) before request_body_take_unref() may free the slot; the immediate return prevents any post-free access.
• Confirmed on_start_buffering (line 4277) can't fire after the last-chunk unref, since resolve consumes the Locked value that carried that callback.
• The scopeguard in end_request_streaming fires on both the ? path and both return Ok(...) paths, and runs after to_error_instance so the rejection acts on a live slot.

Extended reasoning...

Overview

The PR moves the RequestContext's release of its +1 on the pooled Body::Value slot from deinit to the two points where the context stops feeding the slot: the last buffered chunk in on_buffered_body_chunk, and a scopeguard::defer! in end_request_streaming for the incomplete-body path. It also removes the now-redundant explicit unref from deinit (which still releases via the end_request_streaming_and_drain call at its top). Two comments in server_body.rs are updated to point at the field doc. test/harness.ts gains a leakSanitizerEnv() helper, and serve-body-leak.test.ts gains seven cells: four LSan leak cells, one ASAN ordering cell, and two behavioral cells for reading a fully-buffered body after the response.

Security risks

None identified. This is a resource-lifetime fix; no user-controlled input parsing, auth, or crypto is touched.

Level of scrutiny

High. This is a refcount-lifecycle change in RequestContext, which the repo's own review guidance flags as the most-blocked category ("reference counts provably balanced on every terminal path"). The body: &mut Body::Value at line 4060 becomes dangling if used after request_body_take_unref() frees the slot's last ref; the diff places the unref immediately before return and the borrow's last use is at line 4130, so NLL ends it before the unref — but this ordering is load-bearing and only guarded by a comment. The scopeguard in end_request_streaming must fire after to_error_instance (which can enter JS and be the slot's last consumer), and it does — but the ordering-pinning ASAN cell is the only mechanical guard.

Other factors

The PR is unusually well-documented and well-tested: six of the seven new cells are stated to fail on main and pass with the fix, the LSan cells directly reproduce the reported leak, and the collected-Request cells prove the release is safe as the slot's last ref. All comment-cop and CodeRabbit threads are resolved. I traced every reader of self.request_body (is_dead_request, request_body_mut at 2281/4060/4277, on_start_buffering) and each is either idempotent on None or cannot fire after the new release points. I found nothing wrong. Deferring only because refcount-lifecycle changes on the request hot path are the canonical "maintainer should look" category, and the PR itself notes adjacent out-of-scope leaks (parked-context pool slot, cookies) that a maintainer may want to weigh in on.

[claude]

I reviewed this PR and didn't find any bugs. The single-line release in on_buffered_body_chunk mirrors what the streaming arm already does at RequestContext.rs:4036, and I traced the downstream readers (end_request_streaming, is_dead_request, deinit, on_start_buffering) to confirm they all tolerate request_body being None after the last chunk. Because this shifts a refcount release point on a shared pooled slot in Bun.serve's hot path, a maintainer look at the "nothing reads the slot after the last chunk" invariant would still be worthwhile.

What was reviewed:

• Confirmed body (the &mut into the hive slot) is last used at the resolve call before request_body_take_unref(), so the drop that may free the slot does not alias a live borrow.
• Checked that deinit's existing request_body_take_unref() at line 890 is idempotent over None, so the incomplete-body path is unchanged.
• The two open comment-cop flags on lines 153/4133 are length-heuristic hits on ownership docs; the author already justified them on the earlier round and REVIEW.md asks for exactly this kind of "who frees this, when" comment.

Extended reasoning...

Overview

The PR adds one line to src/runtime/server/RequestContext.rs: this.request_body_take_unref() at the end of the if last branch in on_buffered_body_chunk, releasing the request context's ref on the pooled body slot as soon as the final chunk is stored and resolved. The streaming arm of the same function already does this at line 4036. Two doc comments are updated to reflect the new release point, and two comments in server_body.rs are reworded to point at the field doc. Seven new test cells (~300 lines) in serve-body-leak.test.ts cover the leak (LSan under abort / parked pull() / Worker terminate / Request-collected-first), the resolve-before-drop ordering under ASAN, and the user-visible fix that a fully buffered body remains readable after the response is sent.

Security risks

None identified. This is a resource-lifetime change with no input parsing, auth, or trust-boundary implications. The risk class is memory safety (early release → UAF), which the tests address directly: the "resolves a pending read from the last chunk when the Request was collected" cell exercises the case where request_body_take_unref() is the slot's final deref, with ASAN watching the read that resolve performs from the slot just before the drop.

Level of scrutiny

High. This is native refcount-lifecycle code in RequestContext, the per-request state machine of Bun.serve, and REVIEW.md flags exactly this category ("every allocation has exactly one named owner, released exactly once") as the most-blocked. The change is small and mirrors an existing sibling arm, and the PR description enumerates every post-last-chunk reader of the slot with why each tolerates None. I verified those claims against the source: is_dead_request (line 842) and end_request_streaming (line 2278) both branch on Some, deinit (line 890) drops None harmlessly, and on_start_buffering is only reachable via the Locked value that resolve consumes here. That said, a maintainer who knows the full set of paths through RequestContext should confirm no other reader exists.

Other factors

The test coverage is thorough and follows harness conventions (subprocess pipes drained concurrently, bunEnv spread, tempDir, port: 0, socket-error wired to reject the awaited condition per the CodeRabbit round). All CodeRabbit threads are resolved. The two remaining unresolved inline comments are from the comment-cop length heuristic, not human review; the author already argued (and I agree) that the flagged comments state non-local ownership facts rather than justify a workaround. CI build #101596 is referenced as building on the head commit. Given the memory-safety sensitivity and that approval guidelines say not to approve changes to critical code paths, I'm deferring rather than approving.

[claude]

I reviewed this PR and found no bugs. The single-line refcount release in on_buffered_body_chunk mirrors the streaming arm and is placed after resolve so the context's ref still pins the slot while user JS runs; body is not touched after the drop. Because this adjusts refcount lifecycle on a hot Bun.serve path where the &mut into the hive slot is derived through unsafe, a human look is still worthwhile.

Checked: the new request_body_take_unref() call is idempotent with the existing one in deinit (RequestContext.rs:890); end_request_streaming tolerates request_body_mut() returning None; the body reference is last used at line 4127 before the drop at 4134; the two non-gated tests in the last describe block exercise the observable Locked-rejection fix on all platforms.

Extended reasoning...

Overview

The PR adds one functional line in src/runtime/server/RequestContext.rs: this.request_body_take_unref() at the end of the last-chunk branch of on_buffered_body_chunk, immediately after Body::Value::resolve and before return. This releases the request context's +1 on the pooled body slot as soon as the buffered body is complete, matching what the streaming arm already does at line 4036. The remaining diff is doc-comment updates on the request_body field and the two server_body.rs allocation sites, plus ~300 lines of new tests in serve-body-leak.test.ts.

Security risks

None identified. This is a resource-lifetime fix; no untrusted input parsing, auth, or crypto is touched.

Level of scrutiny

High. This is refcount lifecycle in Bun.serve's per-request hot path. request_body_mut() hands out an unbounded &mut Body::Value into the hive slot via unsafe { &mut (*h.as_ptr()).value }; the new call may free that slot, so the ordering against the live body borrow and against resolve (which enters JS) is load-bearing. I traced: (1) body is last dereferenced at line 4127 inside resolve, before the new drop at 4134; (2) during resolve the context still holds its ref, so reentrant JS cannot free the slot out from under body; (3) request_body_take_unref is replace(None) + drop, so the existing call in deinit:890 becomes a no-op rather than a double-deref; (4) end_request_streaming:2278 and is_dead_request handle None correctly.

Other factors

The PR description is unusually thorough and enumerates every reader of the slot after the last chunk. Six of seven new tests are stated to fail on main. The five LSan cells are gated to ASAN/non-Windows; the two behavioural tests (body readable after response) run everywhere. The comment-cop bot flagged the new comments repeatedly and the author pushed back with justification each time — those threads are all resolved. No human reviewer has weighed in yet. Given the unsafe-pointer subtlety and that this is a first human review of a memory-lifetime change in the server, I'm deferring rather than approving.

[robobun]

The one functional line of this PR also fixes a silent data loss in Bun.serve. The description names it only in its third bullet, so here are the numbers. I applied the line (this.request_body_take_unref(); after Body::Value::resolve in the buffering last arm of on_buffered_body_chunk) to main 620b50f. I did not run this branch itself.

The case. The client sends its whole upload (1000 bytes, Content-Length). The handler awaits once, so the body is complete, and then takes Readable.fromWeb(req.body). It reads the Readable after the request ended.

async fetch(req) {
  await auth(); // the whole upload arrives meanwhile
  const body = Readable.fromWeb(req.body);
  await lookup(); // the client disconnects here, or the handler answers 202 first
  await pipeline(body, fs.createWriteStream(path));
  return new Response("stored");
}

Read after the request ended	main 620b50f	main plus this line
pipeline(Readable.fromWeb(req.body), file), the client disconnected	resolves, the file holds 0 bytes (3 of 3 runs)	resolves, the file holds 1000 bytes (3 of 3 runs)
Readable.fromWeb(req.body), the handler answered 202 first	ends cleanly after 0 bytes	reads 1000 bytes
web reader over req.body, taken before the request ended	rejects with an AbortError	reads 1000 bytes
req.text() or req.bytes() in the same place	1000 bytes	1000 bytes

Cause. The context keeps its ref on the body slot after the last chunk. req.body then replaces the stored bytes with a Locked value over a Blob-backed stream. end_request_streaming errors that value at the end of the request, ReadableStream::error cancels the Blob source, and the native Readable pulls Done. With the line the context has released the slot, so nothing errors a complete body.

Tests. The cells below have no sleeps. On main both fail with Expected: 1000, Received: 0 in 3 of 3 runs. With the line both pass in 3 of 3 runs (debug build, Linux x64).

Two cells for Readable.fromWeb(req.body)

import { expect, test } from "bun:test";
import net from "node:net";
import { Readable } from "node:stream";

// The handler takes req.body after the whole upload arrived, and reads it after the request ended.
test.concurrent.each(["the handler answers first", "the client disconnects"])(
  "Readable.fromWeb(req.body) of a complete upload is whole when %s",
  async how => {
    const requestEnded = Promise.withResolvers<void>();
    const result = Promise.withResolvers<number>();
    const taken = Promise.withResolvers<void>();
    await using server = Bun.serve({
      port: 0,
      hostname: "127.0.0.1",
      async fetch(req) {
        // One turn of the loop: the upload came with the headers, so it is complete now.
        await new Promise(resolve => setImmediate(resolve));
        const body = Readable.fromWeb(req.body as any);
        const read = async () => {
          let received = 0;
          for await (const chunk of body) received += chunk.length;
          return received;
        };
        if (how === "the handler answers first") {
          requestEnded.promise.then(read).then(result.resolve, result.reject);
          return new Response("accepted", { status: 202 });
        }
        req.signal.addEventListener("abort", () => requestEnded.resolve());
        taken.resolve();
        await requestEnded.promise;
        await read().then(result.resolve, result.reject);
        return new Response("late");
      },
    });

    const socket = net.connect(server.port, "127.0.0.1");
    socket.on("error", () => {});
    socket.write("POST / HTTP/1.1\r\nHost: x\r\nContent-Length: 1000\r\n\r\n" + Buffer.alloc(1000, "x"));
    if (how === "the handler answers first") {
      // The client has the whole answer, so the server ended the request.
      socket.on("data", data => {
        if (data.toString().includes("accepted")) requestEnded.resolve();
      });
    } else {
      await taken.promise;
      socket.destroy();
    }
    try {
      expect(await result.promise).toBe(1000);
    } finally {
      socket.destroy();
    }
  },
);

Order with #42584. #42584 makes a native Readable.fromWeb() take the error of its web stream. Without this line, the handler above then gets an uncaught 'error' event when the request ends (3 of 3 runs), because the Readable is destroyed before a consumer exists. With this line added to #42584 the handler writes all 1000 bytes (3 of 3 runs). So this PR has to merge before #42584.

Not checked. This branch is far behind main. I did not merge it with main and I did not run its own cells.

[claude]

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

Beyond the inline findings, I also checked the window the new release opens in on_buffered_body_chunk: the _exit scope guard drops (and drains microtasks, running the req.text() continuation) before request_body_take_unref() at src/runtime/server/RequestContext.rs:4271, but the context is pinned for the whole call (RequestContextRef::pin at :4052), so a handler that finishes inside that drain only defers deinit, and deinit/end_request_streaming/is_dead_request all accept a None slot afterwards. Nothing dereferences body after the unref.

Extended reasoning...

The source change is a single added request_body_take_unref() call after the last buffered chunk is stored and any pending Locked promise resolved, plus comment updates at the two hive_alloc sites; it touches no security-sensitive surface. The inline findings are about test coverage (byte-content assertion, close/end wiring, no H2/H3 cell), and the ordering of resolve, microtask drain, and unref was traced against the pin guard and the None-tolerant readers.

[claude]

I re-reviewed the latest push and found no bugs; the three test nits from my earlier pass (failure events wired to reject, exact-bytes assertions, an HTTP/2 transport cell) are all addressed. Because this moves a hive-slot refcount release into the request-body lifecycle and changes observable behavior for late reads, a human look is still worthwhile.

What was reviewed:

• The new release at RequestContext.rs:4271: this is pinned for the whole callback, body is not touched after the release, and the release runs after the enter_event_loop_scope drain so a resolved .text() has already consumed the bytes.
• Every later reader of the slot (is_dead_request, end_request_streaming, deinit, on_abort for H1 and MUX) handles None; the Locked value req.body builds over a complete body carries no ctx pointer, so on_start_buffering is unreachable after the release.
• The 413 paths and the early is_aborted_or_ended return keep the ctx's ref and still release it in deinit; the streaming arm already released at the same point.

Extended reasoning...

The change adds one request_body_take_unref() call in the buffering last arm of on_buffered_body_chunk in src/runtime/server/RequestContext.rs and updates three refcount comments in RequestContext.rs and server_body.rs; the test file gains a 12-cell matrix (3 readers x 2 endings x H1/H2) plus an ASAN-only fixture for the last-ref case. No security-sensitive surface (auth, crypto, injection) is touched. The change is small and mirrors the existing streaming arm, and no findings were produced, but it alters refcount ownership of the pooled body slot in a lifecycle path and makes a user-visible behavior change (late reads of a complete upload now return bytes instead of rejecting), which is why a human look is suggested rather than an outright approval. No CODEOWNERS entry covers the changed files, and no outstanding third-party objections are visible in the timeline metadata.