node:http2: withhold connection window credit after setLocalWindowSize() decreases it

[robobun]

Fixes #43893

Stacked on #40180, which lands first. Review the last three commits.

Problem

• setLocalWindowSize(0), then setLocalWindowSize(2**31-1), ends the session. Bun adds +2147483647 to the peer's 65535: FLOW_CONTROL_ERROR (RFC 9113 §6.9.1).
• H2FrameParser::set_local_window_size (src/runtime/api/bun/h2_frame_parser.rs) ignores a decrease. For 20, then 1 << 20, bun sends +1048556 where node sends +983041.
• node:http2: setLocalWindowSize() inside a frame callback can end the session with FLOW_CONTROL_ERROR on a synchronous JS transport #43893: the call inside a frame callback, on a synchronous transport, ends the session.

Fix

• A decrease works like nghttp2's recv_reduction, as in node. The next old - new bytes earn no WINDOW_UPDATE, and a raise repays them first.
• The binding keeps the size and the reduction (LocalWindow). The engine takes queued changes before each read and WINDOW_UPDATE. That fixes node:http2: setLocalWindowSize() inside a frame callback can end the session with FLOW_CONTROL_ERROR on a synchronous JS transport #43893.
• with_idle_engine() runs what JS deferred during a WINDOW_UPDATE write: a session read, or a resumed stream.
• Verified: fifteen tests in test/js/node/http2/node-http2.test.js, fourteen fail on main and on node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180. Also test/js/node/http2/. Self-reviewed: 7 concerns, all addressed.

Background

• nghttp2 tracks local_window_size (wanted), recv_window_size (used credit) and recv_reduction (withheld credit). WINDOW_UPDATE only adds credit.
• H2FrameParser holds the engine in a RefCell that a read borrows. JS calls during a read are queued.
• Considered an engine-only reduction: JS can call before the engine exists. Considered no write under the borrow: nested frames hit node:http2: a frame is lost when a session takes the cork from another session whose transport _write writes to it #43538.

Downsides

• Behavior change: a lower window now takes effect. After setLocalWindowSize(20), the peer gets 20 bytes for each round trip once its 65535 are used.
• Every session: +16 bytes (H2FrameParser, now 1448). Each read batch: two 16-byte Cell takes, two flag swaps, no allocation. Release binary: +580 bytes (windows-x64).

Notes

• Reproduction: the script from the report (a raw server that logs connection WINDOW_UPDATE increments, and a client that calls setLocalWindowSize(20) and then setLocalWindowSize(1 << 20)):

  runtime	increments	state.localWindowSize
  node v26.3.0	[983041]	1048576
  bun 1.4.1 (main)	[1048556]	1048576
  node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 alone	[1048556]	1114091
  this PR	[983041]	1048576

• The teardown, with a bun client and a bun server in one process: bun 1.4.1 gets GOAWAY with code 3 (FLOW_CONTROL_ERROR) and ERR_HTTP2_SESSION_ERROR. Node and this PR get the response, and state.localWindowSize is 2147483645 in both.

• Who calls this with a smaller value: on bun, the known callers raise the window. grpc-js calls it only for a value above 65535. undici uses its connectionWindowSize option (default 512 KiB). http2-wrapper asks for 4 MiB. After http2: increase default window sizes nodejs/node#64623, the default connection window of node is 32 MiB, so that http2-wrapper call is a decrease on node. Bun still starts at 65535.

• setLocalWindowSize() takes one of three paths. The engine is not created yet (before the first read), the engine is borrowed (a frame callback), or the engine is free (between reads). A temporary log confirmed that the three variants of the first test cover one path each.

• A raise that the withheld credit covers sends nothing while the peer has window left. For 20, then 30000, node and this PR send no WINDOW_UPDATE, and localWindowSize stays 65535. Main sends +29980.

• A raise after the peer used the withheld credit: the peer sends its 65535 bytes after a decrease to 0, and the raise comes between reads. For a raise to 100000, node and this PR send +34465 and then +65535 at once. For a raise to 65535, node sends nothing, and its transfer stalls. This PR sends +65535. The first version of this PR waited for the next inbound frame.

• The last test covers a decrease in a PING callback, with 40000 bytes of DATA after the PING in the same read. Node withholds all 40000 bytes (localWindowSize 25535). Without the engine-side take, the WINDOW_UPDATE check at the end of the read used the old size and granted 40000.

• A write can run JS: cork() flushes the output of another session, and a JS transport runs its _write at once. A setLocalWindowSize() call from there goes into the same queue, so the outer change applies first. The test a setLocalWindowSize() call from inside a transport write covers this. With the queue applied late, it sends [10] where two calls in a row send [10, 65525].

• set_local_window_size rejects a size outside 0..=2^31-1. The JS layer checks the range first.

• Interop: a 70000 byte upload and a 70000 byte response, with both windows lowered to 20. All four pairs of bun and node finish, and the final state matches node.

• As in node, state.localWindowSize is the window that the peer still has, so a decrease alone does not lower it.

• A review found a hang in an earlier version of this PR. set_local_window_size let the engine write a WINDOW_UPDATE while it held the engine borrow. With two sessions in one process over duplexPair(), that write flushed the other session's corked PING into this session. read() found the engine borrowed and only queued the bytes, and nothing read them until the next frame came in. main does not hang there, because it writes before it borrows. The test frames that arrive while setLocalWindowSize() writes its WINDOW_UPDATE are read times out on that version, and also when the drain is removed from with_idle_engine(). It fails on main and on node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180.

• A second review finding, same cause: JS inside that write can resume a paused stream of the same session. set_stream_reading then finds the engine borrowed and leaves its stream WINDOW_UPDATE to the batch end, but this holder had none. A deferred call now sets engine_work_deferred, and with_idle_engine() runs replenish_windows() while that flag is set. The flag keeps _read() free of the scan over all streams. The test a stream resumed while setLocalWindowSize() writes its WINDOW_UPDATE gets its window back gets streamIncrements: [] without the fix. It needs large windows: under default windows the peer can send 65535 bytes, one less than the 64 KiB that a stream buffers, so the stream never pauses natively.

• A third review finding, same cause: JS inside a WINDOW_UPDATE write of the batch end itself can call setLocalWindowSize() or resume a stream. That call came too late for the pass that was running. replenish_windows() now loops: each pass first takes engine_work_deferred, and it runs again if its own writes deferred a call. So receive() and with_idle_engine() get this through one function. The test a setLocalWindowSize() call from inside a batch-end write takes effect in that batch gets increments: [] without the fix. It passes on main and on node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 alone, where the batch end sends that update itself, because nothing is withheld. A session on a native socket cannot reach this case: bun flushes every cork when a JS callback returns to native code. The test runs the session on a duplexPair(), where the read runs inside a JS call.

• The resumed-stream test failed on both Windows lanes of build 120069. That was a flaw in the test. read() returned only the first buffered chunk, and on Windows that chunk was small, so read() never reached _read(). The test now reads the whole buffer, and it sizes the windows (stream 200000, connection 150000, 120000 bytes of DATA) so that the stream pauses before its update comes due, however the transport splits the reads. On a Windows machine, all 23 setLocalWindowSize() tests pass in five runs, and the whole file passes (413 pass, 6 skip).

• rewrite_read() only applies queued window changes before receive() and writes nothing there. A write at that point could put a re-entrant read ahead of the bytes of the current read.

• set_stream_reading had the same shape before this PR (replenish_stream writes under the borrow), so it uses with_idle_engine() too. That site has no failing test: in my attempt the deferred stream WINDOW_UPDATE went out before the other session had a corked frame. The helper changes nothing there unless bytes were queued during the call.

• Not fixed here, older than this PR: cork() resets its offset after it takes the cork from another session, so a frame that the flush's JS corked for this session is lost (node:http2: a frame is lost when a session takes the cork from another session whose transport _write writes to it #43538). A nested setLocalWindowSize() raise with a positive increment loses its WINDOW_UPDATE that way, on main too. The engine path of this PR avoids it: a nested change stays queued until the outer write returns.

• RecvWindow::apply calls grow(), which node:http2: apply INITIAL_WINDOW_SIZE changes to open streams #41329 also calls for stream windows. This PR and node:http2: apply INITIAL_WINDOW_SIZE changes to open streams #41329 conflict in one hunk of h2_frame_parser.rs: node:http2: apply INITIAL_WINDOW_SIZE changes to open streams #41329 moves the sync section of rewrite_read() into sync_engine(). The PR that lands second moves the apply_recv_window_changes() call into that function.

• Rebased onto main after build: link the Rust crates' rlibs directly; no libbun_runtime.a #43650. That PR made the h2 engine pub(crate), and the workspace lint unreachable_pub = "deny" then rejected the plain pub items here: RecvWindow::apply, RecvWindowChange, RecvWindowChange::increment, LocalWindow, LocalWindow::resize and Connection::sync_recv_window. They are pub(crate) now. Struct fields stay pub, as on main. The earlier commits of this PR are one commit now.

• Rebased onto the head of node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 (b21031b) on 2026-09-24. Its six commits come first on this branch, unchanged. node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 lands first, and its Notes name this PR as the owner of the accounting after a decrease. That head pins two orders with tests, and this PR keeps both. replenish_connection_window mirrors the window before it writes, so session.state is current inside the write. A read() that re-enters inside the WINDOW_UPDATE write of setLocalWindowSize() takes the queued change before receive(), so the engine checks that DATA against the new window. With each of the two lines reverted, exactly the matching node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 test fails.

• node:http2: setLocalWindowSize() inside a frame callback can end the session with FLOW_CONTROL_ERROR on a synchronous JS transport #43893: setLocalWindowSize() inside a frame callback, on a transport that delivers the peer's answer synchronously. On node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 the read that re-enters is queued, and the drain loop of rewrite_read() fed it to the engine before the window growth was applied, so a body of 65536 bytes ended the session with FLOW_CONTROL_ERROR. Here the engine takes queued changes at the end of each batch, which is before that drain. The script from the issue prints received for 65535, 65536 and 100000 bytes on this branch, and an error for the last two on node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180. Node aborts on that transport with its own assertion, so there is no node result. The test accepts DATA that answers a setLocalWindowSize() call made inside a frame callback is that script.

• No user reported either case.

• Measurements for Downsides, against the head of node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180. size_of::<H2FrameParser>() is 1432 bytes there and 1448 bytes here (read from a temporary const assertion, linux-x64). Release builds on windows-x64, llvm-size -A: .text 63735611 to 63736123 (+512), .rdata 19938624 to 19938688 (+64), .reloc +4, 580 bytes in all. The file grows by 512 bytes (87818752 to 87819264). For each read batch the engine calls take_recv_window_change() twice (a 16-byte Cell take and a compare) and take_deferred() twice (a Cell<bool> swap). node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 already has one such take before receive().

• The tests for a smaller window sit in a nested describe inside the block of node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180, and they use its ready(), frame() and frameReader() helpers. Each wait rejects when its session or stream emits error, or emits close before the result is in. In a scratch test, a peer that drops the socket rejects the wait in 387 ms with closed before the test had its result. The old wiring waited for the test timeout there.

• With the decrease in effect, the test a smaller size keeps the window the peer already has of node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 got slow. After the first 65535 bytes its peer gets 20 bytes for each round trip, so the 100000 byte body took 1724 round trips (1548 ms on the debug build). The body is now 65535 + 200 bytes: ten round trips, 157 ms. The test still passes on node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 alone.

• h2-conformance.test.ts failed once in a GC count test (stream release after a queued END_STREAM, 5 live streams where the limit is 3). It does not call setLocalWindowSize(). It passed in three filtered runs and in two runs of the whole file.

• Also run with the debug build: node-http2.test.js, the other files in test/js/node/http2/, and test-http2-client-setLocalWindowSize.js, test-http2-server-setLocalWindowSize.js, test-http2-window-size.js, test-http2-session-stream-state.js, test-http2-misbehaving-flow-control.js, test-http2-window-update-overflow.js and 19 more test-http2-* files. cargo clippy -p bun_runtime is clean.

---

[human-review] gate passed · iteration 0 · 4 files touched

fails on main (without fix)

ASAN without fix: 21 failed, 6 skipped
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/pr_gate.xml" "test/js/node/http2/node-http2.test.js"
bun test v1.4.3 (367d939d9)

test/js/node/http2/node-http2.test.js:
(pass) node none > Client Basics > should be able to send a GET request [1015.61ms]
(pass) node none > Client Basics > should be able to send a POST request [755.28ms]
(pass) node none > Client Basics > constants [27.98ms]
(pass) node none > Client Basics > getDefaultSettings [3.35ms]
(pass) node none > Client Basics > getPackedSettings/getUnpackedSettings [25.60ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is too small [7.81ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a multiple of 6 bytes [4.42ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a buffer [7.41ms]
(pass) node none > Client Basics > should be able to send data using end [803.42ms]
(pass) node none > Client Basics > should be able to mutiplex GET requests [781.26ms]
(pass) node none > Client Basics > http2 should receive remoteSettings when receiving 
... (truncated)

release without fix: 23 failed, 6 skipped
bun test v1.4.3-canary.1 (367d939d9)

test/js/node/http2/node-http2.test.js:
(pass) node none > Client Basics > constants [0.83ms]
(pass) node none > Client Basics > getDefaultSettings [0.04ms]
(pass) node none > Client Basics > getPackedSettings/getUnpackedSettings [0.26ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is too small [0.13ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a multiple of 6 bytes [0.04ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a buffer [0.06ms]
(pass) node none > Client Basics > is possible to abort request [1.62ms]
(pass) node none > Client Basics > aborted event should work with abortController [0.93ms]
(pass) node none > Client Basics > aborted event should work with aborted signal [0.88ms]
(pass) node none > Client Basics > signal validation matches node: non-signal objects throw, duck-typed { aborted } is accepted [0.90ms]
(pass) node none > Client Basics > should fail to connect over HTTP/1.1 [36.24ms]
(skip) node none > Client Basics > should not leak memory
(pass) node none > Client Basics > headers cannot be bigge
... (truncated)

passes on PR (with fix)

ASAN with fix: 6 skipped
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/pr_gate.xml" "test/js/node/http2/node-http2.test.js"
bun test v1.4.3 (367d939d9)

test/js/node/http2/node-http2.test.js:
(pass) node none > Client Basics > should be able to send a GET request [1100.50ms]
(pass) node none > Client Basics > should be able to send a POST request [777.29ms]
(pass) node none > Client Basics > constants [29.63ms]
(pass) node none > Client Basics > getDefaultSettings [3.14ms]
(pass) node none > Client Basics > getPackedSettings/getUnpackedSettings [26.36ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is too small [7.75ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a multiple of 6 bytes [4.39ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a buffer [7.53ms]
(pass) node none > Client Basics > should be able to send data using end [817.67ms]
(pass) node none > Client Basics > should be able to mutiplex GET requests [803.42ms]
(pass) node none > Client Basics > http2 should receive remoteSettings when receiving 
... (truncated)

release with fix: 6 skipped
$ bun scripts/build.ts --profile=release
[configured] bun-profile → bun (stripped) in 1128ms (unchanged)
ninja: Entering directory `/workspace/bun/build/release'
[1/224] gen generated_host_exports.rs
generated_host_exports.rs: 121 exports (host=5, lazy=10, generic=106, rust=0); 245 extern-C blocks audited
[2/224] gen ZigGeneratedClasses.{cpp,h,rs}
Found 2 classes from /workspace/bun/src/jsc/resolve_message.classes.ts
  - ResolveMessage (15 fields)
  - BuildMessage (10 fields)
Found 1 classes from /workspace/bun/src/runtime/api/Archive.classes.ts
  - Archive (4 fields, 1 class fields)
Found 2 classes from /workspace/bun/src/runtime/api/BunObject.classes.ts
  - ResourceUsage (8 fields)
  - Subprocess (20 fields)
Found 1 classes from /workspace/bun/src/runtime/api/cron.classes.ts
  - CronJob (5 fields)
Found 3 classes from /workspace/bun/src/runtime/api/filesystem_router.classes.ts
  - FileSystemRouter (5 fields)
  - FrameworkFileSystemRouter (2 fields)
  - MatchedRoute (8 fields)
Found 1 classes from /workspace/bun/src/runtime/api/Glob.classes.ts
  - Glob (5 fields)
Found 1 classes from /workspace/bun/src/runtime/api/h2.classes.ts
  - H2FrameParser (29 fields)
Found
... (truncated)

diff hotspot

src/runtime/api/bun/h2/connection.rs   |  98 +++-
 src/runtime/api/bun/h2/flow_control.rs | 110 +++-
 src/runtime/api/bun/h2_frame_parser.rs | 154 +++---
 test/js/node/http2/node-http2.test.js  | 917 +++++++++++++++++++++++++++++++++
 4 files changed, 1182 insertions(+), 97 deletions(-)

gate history · 5 passed · 0 rejected · iteration 0

evidence per changed file

file                                    reads  edits  tests
src/runtime/api/bun/h2/connection.rs       11     17    157
src/runtime/api/bun/h2/flow_control.rs      6     12    156
src/runtime/api/bun/h2_frame_parser.rs     29     33    156
test/js/node/http2/node-http2.test.js      21     23    156

[robobun]

Status: reproduced on bun 1.4.1. This PR fixes it.

• Teardown: a client calls setLocalWindowSize(0), then setLocalWindowSize(2 ** 31 - 1), then sends one request to http2.createServer(). Bun 1.4.1 gets GOAWAY with FLOW_CONTROL_ERROR. Node v26.3.0 and this branch get the response.
• Wire value: a raw server logs the connection WINDOW_UPDATE after setLocalWindowSize(20) and setLocalWindowSize(1 << 20). Bun 1.4.1 sends +1048556. Node and this branch send +983041.
• node:http2: setLocalWindowSize() inside a frame callback can end the session with FLOW_CONTROL_ERROR on a synchronous JS transport #43893: the script from that issue ends the session with ERR_HTTP2_ERROR for bodies of 65536 and 100000 bytes on node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180. On this branch it prints received for both.
• Of the fifteen new tests in test/js/node/http2/node-http2.test.js, fourteen fail on a debug build of node:http2: keep setLocalWindowSize() off SETTINGS_INITIAL_WINDOW_SIZE #40180 (b21031b). The same fourteen failed on main (8d36bff) before the latest restructure of the tests. The fifteenth guards a write path that only this PR has. All fifteen pass on this branch, and so does the whole file (413 pass, 0 fail), on Linux and on a Windows machine.

Rebased onto the head of #40180 (b21031b) on 2026-09-24. #40180 lands first. Its six commits come first in this PR, unchanged. Review the last three commits. That head pins two orders with tests, and this PR keeps both: session.state is current inside the engine's own WINDOW_UPDATE write, and DATA that a JS transport delivers from inside the WINDOW_UPDATE write of setLocalWindowSize() is checked against the new window. With each of the two lines reverted, exactly the matching #40180 test fails.

Earlier reviews found three hangs with one cause, and all three are fixed. setLocalWindowSize() lets the engine write a WINDOW_UPDATE, and a write can run JS. A call from that JS finds the engine busy and defers its work. with_idle_engine() and the engine's batch end now do the deferred work. Each fix has a test that fails without it.

Latest push (b4dfac5), tests only. The tests for a smaller window now sit inside the setLocalWindowSize() describe block of #40180 and use its helpers. Each wait rejects when its session or stream fails, or closes early. The test a smaller size keeps the window the peer already has now downloads 65535 + 200 bytes. With the decrease in effect, its 100000 byte body needed 1724 round trips (1548 ms on the debug build). It now needs ten (157 ms).

The PR body now has a Downsides section with measured costs: +16 bytes for each session, and +580 bytes in the windows-x64 release binary.

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📒 Files selected for processing (4)

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---

Walkthrough

Changes

HTTP/2 receive-window handling now tracks resize deltas and withheld credit. The parser synchronizes changes with the connection engine and reports effective receive state. Tests cover resizing, window limits, peer consumption, and callback timing.

Receive-window synchronization

Layer / File(s)	Summary
Receive-window change model src/runtime/api/bun/h2/flow_control.rs	RecvWindowChange and LocalWindow track size and consumed deltas. Decreases withhold credit, and increases repay withheld credit before emitting additional WINDOW_UPDATE credit. Unit tests cover these cases.
Parser window state and resizing src/runtime/api/bun/h2_frame_parser.rs	The parser stores LocalWindow, mirrored engine counters, and pending RecvWindowChange values. setLocalWindowSize() applies or defers complete changes. State reporting uses effective receive-window values.
Engine synchronization and validation src/runtime/api/bun/h2/connection.rs, src/runtime/api/bun/h2_frame_parser.rs, test/js/node/http2/node-http2.test.js	Sink callbacks transfer receive-window state. Connection applies queued changes during synchronization and reports state after DATA receipt. Tests cover large bodies, resizing, limits, peer consumption, and callback timing.

Suggested reviewers: dylan-conway, cirospaciari

Merge Risk: ⚪ Minimal · up to 76131

This change makes setLocalWindowSize() in node:http2 handle shrinking and regrowing the connection receive window correctly. Bun now avoids over-advertising flow-control credit and no longer triggers FLOW_CONTROL_ERROR session termination. The earlier range-validation and ordering concerns are marked as fixed, and no outstanding defects remain, so the change looks ready to merge.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly describes the main change: withholding connection-window credit after setLocalWindowSize() decreases it.
Description check	✅ Passed	The description explains the problem, the fix, and how the author verified it. Although it does not use the template’s exact headings, it covers both required sections in detail.

---

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[robobun]

^{Updated 10:48 AM PT - Sep 24th, 2026}

✅ @robobun, your commit b4dfac5268d5afc71cc96656fde66adeaed81ff4 passed in Build #120347! 🎉

---

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Inline comments:
In `@src/runtime/api/bun/h2_frame_parser.rs`:
- Line 4536: Restore the 31-bit range validation in set_local_window_size by
rejecting windowSize values outside 0..=MAX_WINDOW_SIZE before converting or
updating LocalWindow, keeping engine and peer window state consistent.
- Around line 4547-4553: Update the receive-window change handling around
engine.apply_recv_window_change and pending_recv_window_change so change is
recorded or applied before any transport write that may synchronously re-enter
JS. Ensure nested setLocalWindowSize calls observe the outer change first, and
drain the queued change before running replenish_connection_window or other
replenishment checks.

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Run ID: 63b1eee0-edcd-44f6-aeb4-5e927869d1d8

📥 Commits

Reviewing files that changed from the base of the PR and between c8023f4 and 8033116.

📒 Files selected for processing (3)

• src/runtime/api/bun/h2/connection.rs
• src/runtime/api/bun/h2/flow_control.rs
• src/runtime/api/bun/h2_frame_parser.rs

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[claude]

Code review found no issues

No high-confidence issues detected in this change.

[claude]

Findings marked 🟡 are optional suggestions and need no follow-up push.

[claude]

Code review completed

Nothing new to post: everything this review found is already covered by existing comments on this pull request or didn't merit a separate one.

Still open from earlier reviews (3):

• 🔴 src/runtime/api/bun/h2_frame_parser.rs:4582 — Inbound frames that arrive while setLocalWindowSize() writes its WINDOW_UPDATE are left unparsed until the next unrelat…
• Also unresolved: 2 minor or pre-existing.

If you have decided not to act on one of these findings, resolve its thread (a reply alone leaves it open) and the next review stops counting it. To review this commit again now, use Re-run on its "Claude Code Review" check.

[claude]

Code review completed

Nothing new to post: everything this review found is already covered by existing comments on this pull request or didn't merit a separate one.

[claude]

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

[claude]

Code review completed

Nothing new to post: everything this review found is already covered by existing comments on this pull request or didn't merit a separate one.