docs: cover four undocumented behaviour changes and the CLI flags the reference pages lack

[robobun]

Problem

• Four user-visible changes since 1.4.2 have no sentence in docs/: the CompressionStream level option (CompressionStream: honor a level option for brotli, zstd, and the zlib formats #40100), Connection: close with pipelined requests in Bun.serve (Bun.serve: stop dispatching pipelined requests after Connection: close (RFC 9112 9.6) #33005, Bun.serve: do not run the requests behind a response that closes the connection #42986), view transition classes in CSS modules (css: export view-transition pseudo-element classes from CSS modules #42729, css: parse ::view-transition-group-children() as a view transition pseudo-element #42779), and the 128 + signal exit status of an interrupted bun test (bun test --parallel: exit 128 + signal, kill what a crashed worker spawned #41467).
• docs/test/runtime-behavior.mdx says SIGTERM "gracefully stops test execution". On main no afterEach or afterAll hook runs after SIGTERM or SIGINT.
• The CLI reference pages in docs/snippets/cli/ lag --help: test.mdx lacks 14 flags, run.mdx 31, the install pages --offline, --prefer-offline and others.

Fix

• Add a sentence or a short section per change: nodejs-compat.mdx (level), http/server.mdx (Connection: close section), bundler/css.mdx ("View transitions" subsection), test/runtime-behavior.mdx (exit code line, correct Signal Handling text).
• Add a ParamField for each flag that --help prints and the page lacks. The text follows the help text.
• Not added: --test-worker (internal), the flags that docs(pm): add the missing flags to the bun install and bun add flag references #38839 and docs: --no-bundle flag scope, standalone HTML CSP and duplication, input sourcemaps, --pass-with-no-tests, overwrite behavior #41937 already add, and publish.mdx.
• Verified: I ran each documented behaviour on a debug build of main 630e921 (output in the Notes). Docs only, so no test change.

Background

• The files in docs/snippets/cli/ are hand-written <ParamField> lists that the command pages import. No script generates them.
• HTTP pipelining: a client sends several requests on one connection before it reads the first response. RFC 9112 section 9.6 forbids the server to process requests behind one that closes the connection.
• A CSS module exports an object that maps each local class name to its scoped name.

Notes

Not in this PR, because another open PR or file already has it

• The console depth for arrays, Map and Set (console: apply depth cap to Map/Set/Array entries and Error cause chains #35288): docs: correct the --console-depth output samples #43037.
• The interrupt exit codes in docs/test/parallel.mdx (bun test --parallel: exit 128 + signal, kill what a crashed worker spawned #41467): docs(test): correct which worker deaths abort a --parallel run, add interrupt exit codes #43039. This PR only touches runtime-behavior.mdx for that change.
• YAML.stringify (yaml: fix block-style layout: no trailing space after a key, empty collections inline, item alignment for any indent #39961): docs, bun-types: restore the YAML.stringify section, document Bun.markdown.ansi, correct two JSDoc statements #42526 restores the section, with the flow and block sentence.
• drainMicrotasks() (bun:jsc: drainMicrotasks() no longer runs the event loop's task queue #42811): packages/bun-types/jsc.d.ts already says that the event loop does not run. The bun:jsc reference page is generated from that file.
• jsx: remove the dead Solid runtime from bunfig, the CLI, and tsconfig #41699 (jsx = "solid"), js_parser: lower standard decorators without moving class members #40833 (decorators), elf: fix bun build --compile from a compiled executable (regression in 1.3.14) #42894 (--compile from a compiled executable), install: keep a bundled file: dependency bundled when installing from bun.lock #42884 and url: end the authority where new URL() ends it #42881 (bun install): no page states the old behaviour, so there is nothing to correct.

Output on main 630e921 (debug build, linux x64)

CompressionStream, 160 kB of repeated text:

gzip         default 901 | level 0: 160033 | level 1: 1735 | level 9: 276
brotli       default 20 | level 0: 100 | level 4: 20 | level 11: 20
gzip 99  -> RangeError: The compression level must be an integer between 0 and 9 for gzip
gzip 1.5 -> RangeError: The compression level must be an integer between 0 and 9 for gzip
brotli 12 -> RangeError: The compression level must be an integer between 0 and 11 for brotli
zstd 0   -> RangeError: The compression level must be an integer between 1 and 22 for zstd

Bun.serve, one write of pipelined requests over a raw socket. rc is a request that the handler answers with a Connection: close header:

/a (Connection: close), /b        handlers ran: /a      server closed: true
/0, /1 (Connection: close), /2, /3  handlers ran: /0 /1   server closed: true
/a (HTTP/1.0), /b                 handlers ran: /a      server closed: true
/a (HTTP/1.0 + keep-alive), /b    handlers ran: /a      server closed: true
/a, /b?rc, /c, /d                 handlers ran: /a /b   server closed: true
/a, /b, /c                        handlers ran: /a /b /c  server closed: false

The canary at c6b7fcb (before #33005) runs the handler of every request in all six cases. A static Response in routes with a Connection: close header does not close the connection on main, so the new text names only the response that a handler returns.

CSS module with one rule for each of the five pseudo-elements, for example ::view-transition-group(.slide):

::view-transition-group(.slide_-MSaAA) {
::view-transition-group-children(.kids_-MSaAA) {
::view-transition-image-pair(.pair_-MSaAA) {
::view-transition-old(.old_-MSaAA) {
::view-transition-new(.new_-MSaAA) {
{"card":"card_-MSaAA","slide":"slide_-MSaAA","kids":"kids_-MSaAA","pair":"pair_-MSaAA","old":"old_-MSaAA","new":"new_-MSaAA"}

bun test with a 20 s test, signal sent after 3 s from Bun.spawn. Each test file writes a marker file from afterEach and afterAll:

serial SIGTERM:      exitCode=null signalCode=SIGTERM  afterEach ran=false afterAll ran=false
serial SIGINT:       exitCode=null signalCode=SIGINT   afterEach ran=false afterAll ran=false
parallel=2 SIGTERM:  exitCode=143  signalCode=null     afterEach ran=false afterAll ran=false
parallel=2 SIGINT:   exitCode=130  signalCode=null

A shell reports 143 and 130 for the two serial rows.

CLI flags

• I compared the <ParamField path> values of each page with the flags of bun <command> --help. src/runtime/cli/ is the same at c6b7fcb and 630e921.
• I ran these flags on the debug build and saw the documented effect: --changed, --changed=HEAD~1, --no-env-file, --no-warnings, --disable-warning, --redirect-warnings, --tls-min-v1.3, --tls-max-v1.2, --feature, --cron-title with --cron-period (both are required, and Bun calls scheduled()), --experimental-stream-iter.
• --heap-prof-interval: src/runtime/cli/Arguments.rs:1383 accepts the flag for Node.js parity and does not use it. The text follows docs/project/benchmarking.mdx, not the help text.
• --quiet on the install pages: it selects LogLevel::Quiet, and show_progress() is false for it. bun install --quiet prints the same lines as bun install. The text is the one link.mdx and patch.mdx already use.
• publish.mdx is not changed. The help of bun publish lists the shared install flags (--global, --lockfile-only, --linker), and the page documents only the flags that apply to a publish.
• prettier --check passes on every changed file.

---

no test proof · iteration 0 · docs-only change; test-proof not applicable

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📥 Commits

Reviewing files that changed from the base of the PR and between 630e921 and 3e17890.

📒 Files selected for processing (14)

• docs/bundler/css.mdx
• docs/runtime/http/server.mdx
• docs/runtime/nodejs-compat.mdx
• docs/snippets/cli/add.mdx
• docs/snippets/cli/build.mdx
• docs/snippets/cli/install.mdx
• docs/snippets/cli/link.mdx
• docs/snippets/cli/outdated.mdx
• docs/snippets/cli/patch.mdx
• docs/snippets/cli/remove.mdx
• docs/snippets/cli/run.mdx
• docs/snippets/cli/test.mdx
• docs/snippets/cli/update.mdx
• docs/test/runtime-behavior.mdx

---

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[robobun]

^{Updated 2:34 AM PT - Sep 17th, 2026}

✅ @robobun, your commit 3e1789063120e3bebcbba1667294783da9e5675e passed in Build #116956! 🎉

---

🧪   To try this PR locally:

bunx bun-pr 43044

That installs a local version of the PR into your bun-43044 executable, so you can run:

bun-43044 --bun

[robobun]

Status

• Reproduced: I ran each documented behaviour on a debug build of main 630e921 (linux x64). The PR body has the output under Notes.
  • new CompressionStream("gzip", { level }): 901 bytes by default, 1735 at level 1, 276 at level 9. Level 99 and level 1.5 throw a RangeError.
  • Bun.serve, pipelined requests over a raw socket: the handlers behind a Connection: close request, an HTTP/1.0 request, or a handler response with Connection: close do not run, and the server closes the connection.
  • A CSS module with ::view-transition-group(.slide) exports slide. The same holds for the other four view transition pseudo-elements.
  • bun test after SIGTERM or SIGINT: a shell reports 143 or 130. --parallel exits with that code. No afterEach or afterAll hook runs.
• CLI pages: I compared the <ParamField path> values of each page with bun <command> --help, and ran the flags that change behaviour.
• Not in this PR: the console depth text is in docs: correct the --console-depth output samples #43037, the --parallel interrupt text is in docs(test): correct which worker deaths abort a --parallel run, add interrupt exit codes #43039, and the YAML.stringify section is in docs, bun-types: restore the YAML.stringify section, document Bun.markdown.ansi, correct two JSDoc statements #42526.
• PR: docs: cover four undocumented behaviour changes and the CLI flags the reference pages lack #43044

[claude]

Code review found no issues

No high-confidence issues detected in this change.

8 verified lower-impact observations (convention, logging or cleanup points) were not posted.