rose-ash/spec/tests/hyperscript-feature-audit-0.9.90.md

_hyperscript 0.9.90 Gap Audit

Date: 2026-04-22 Target release: upstream 0.9.90 (2026-04-13), with awareness of 0.9.91 bugfixes (2026-04-14) Supersedes: hyperscript-feature-audit.md (2026-04-09)

Our implementation lives in /root/rose-ash/lib/hyperscript/:

• tokenizer.sx (618 lines), parser.sx (2414 lines), compiler.sx (1739 lines), runtime.sx (1609 lines), integration.sx (109 lines).

Tests in spec/tests/test-hyperscript-*.sx + extracted fixture hyperscript-upstream-tests.json (831 entries).

---

1. Version alignment

What release is our JSON snapshot from?

The fixture spec/tests/hyperscript-upstream-tests.json and the prior audit were both written on 2026-04-09 (four days before 0.9.90 tagged on 2026-04-13). File timestamps confirm this; there is no earlier git history for the JSON (it first appears in commit 7492ceac).

The contents are clearly 0.9.90 (pre-tag) or equivalent:

• 63 on tests, 44 bind, 41 when, 23 live, 10 liveTemplate, 19 component, 4 reactive-properties — all new-in-0.9.90 reactivity features
• 10 morph, 8 reset, 13 empty, 10 dialog, 4 swap, 7 halt, 5 askAnswer, 3 focus, 8 scroll, 23 fetch including fetch:beforeRequest/fetch:error lifecycle — all 0.9.90 features or overhauls
• Keywords between, ignoring (case), precedes/follows, where, sorted/mapped/split/joined by — 0.9.90 collection expressions
• Total 831 tests vs upstream's "~1332 tests" claim for 0.9.90 — we have the subset that was non-sinon, non-script-tag, non-dialog-API when extracted

Conclusion: the JSON is a valid 0.9.90-era snapshot. No re-extraction is strictly required, but upstream added tests post-tag (changelog mentions 1332 tests at 0.9.90 release) — we may be missing late additions.

What 0.9.90 added over 0.9.8 / 0.9.14

Full changelog consulted at github.com/bigskysoftware/_hyperscript/blob/master/CHANGELOG.md.

Breaking changes in 0.9.90:

• processNode() → process()
• as JSON now parses a string; old stringify behavior → as JSONString; as Values | JSONString / as Values | FormEncoded replace Values:JSON / Values:Form
• default uses nullish check (no longer overwrites 0/false)
• go to url ... deprecated → go to /path or go to "url"
• go to the top of ... deprecated → scroll to the top of
• async keyword removed (was confusing)
• /* */ block comments removed
• transition width → transition *width (explicit * style ref)
• fetch throws on non-2xx by default; do not throw or as Response restores old behavior
• [@attr] bracket-style attribute access deprecated (still parsed, use @attr)

New features in 0.9.90:

• Reactivity (live, when ... changes, bind) — dependency tracking + UI updates
• Templates in core — render command + <template> elements + ${} interpolation + #for/#if/#else/#end
• morph command (idiomorph-based DOM morph)
• Components system — <template component="name"> custom elements with slots
• DOM-scoped variables (^name)
• open / close, focus / blur, empty / clear, reset, swap, select, ask / answer, speak, breakpoint
• toggle between attributes: toggle between [@data-state='active'] and [@data-state='inactive']
• toggle x between a, b and c N-way cycle
• Collection expressions: where, sorted by, mapped to, split by, joined by
• Magic symbols: clipboard, selection
• on resize (ResizeObserver), on first click (one-shot)
• view transition command (View Transitions API)
• intercept feature (service-worker DSL)
• Pipe operator | for chained conversions (as Values | JSONString)
• repeat ... until x end / repeat ... while x end (bottom-tested)
• ignoring case modifier on comparisons
• between, starts with, ends with comparisons
• put null into @attr removes attribute
• DOM expressions (#id, .class, <sel/>) are writable via .replaceWith()
• set arr to arr + [1, 2] array concatenation
• cleanup() API + hyperscript:before/after:init / :cleanup lifecycle events + data-hyperscript-powered

0.9.91 bugfixes (worth tracking):

• on resize from window/document falls through to native resize (not ResizeObserver)
• toggle ... for <duration> no longer consumes a following for-in
• ${} template hang fix (debug log leftover)

---

2. Category coverage gap

Our behavioral test file test-hyperscript-behavioral.sx contains 67 defsuite blocks covering 52 unique JSON categories. The file has 831 eval-hs calls matching the 831 JSON entries — every upstream test has a behavioral entry, but 89 of them are replaced with safe no-op / NOT-IMPLEMENTED stubs (commit 71cf5b84).

Per-category upstream size vs. stub count:

Category	Upstream tests	Stubs in behavioral	Simple-clean upstream (estimate)	Status
on	63	32	~30	many non-simple (event queue / debounced / throttled / intersection / mutation)
bind	44	~44	1	almost entirely new-0.9.90, not implemented
when	41	~36	5	when ... changes reactivity mostly missing
comparisonOperator	40	~36	4	starts with / ends with / between / ignoring case mostly missing
put	38	8	37	implemented; stubs are complex positional forms
toggle	30	2	28	strong coverage
repeat	30	4	23	break / continue / until now work (recent commits)
def	27	7	3	basic only; async/catch variants partial
set	25	7	24	strong; stubs are array-concat and rare forms
dom-scope	25	—	23	23/25 upstream simple — ^var works
transition	23	1	22	strong
live	23	—	0	0/23 clean-simple — reactivity runtime missing
fetch	23	3	6	11/23 passing per recent commit 5c66095b; sinon-required tests stubbed
collectionExpressions	22	—	5	where / sorted by / mapped to / split by / joined by — new 0.9.90, mostly missing
increment	20	—	20	full
if	19	—	18	full
component	19	—	14	14/19 simple — <template component> custom-element bridge missing on JS host
add	19	4	18	full minus [@attr] / {css} forms
asExpression	17	—	0	0/17 simple — as JSON/JSONString/FormEncoded + pipe operator missing
remove	14	4	12	strong
hide	14	—	14	full
bootstrap	14	—	2	2/14 simple — lifecycle events / cleanup() / data-hyperscript-powered not covered
empty	13	—	12	full (recent commit 802ccd23)
append	13	5	13	strong
take	12	—	12	full
tell	10	6	10	parses; stubs are the multi-statement tell variants
morph	10	—	4	4/10 simple — string target variant works, element-target variants stubbed
liveTemplate	10	—	7	7/10 simple — no implementation of <template> + #for/#if
dialog	10	1	5	5/10 simple — dialog open/close partial
default	9	—	9	full
send	8	—	8	full
scroll	8	—	0	0/8 simple — scroll to command not implemented
reset	8	—	8	full (recent commit 802ccd23)
evalStatically	8	—	0	0/8 simple — static eval API not exposed
assignableElements	8	—	3	partial
wait	7	—	7	full
splitJoin	7	—	0	0/7 simple — split by / joined by absent
pick	7	—	0	0/7 simple — regex/char/item pick missing
parser	7	—	3	partial
halt	7	—	6	full (recent commit 802ccd23)
call	6	7	5	partial — call functions that return promises stubbed
no	5	—	1	no <expr> predicate mostly missing
mathOperator	5	—	0	0/5 simple — mod/abs + async math promise-aware ops missing
go	5	—	3	basic go to works; new scroll to form missing
askAnswer	5	—	0	0/5 simple — ask / answer not parsed
swap	4	—	4	full
socket	4	—	0	extension, out of scope
select	4	—	0	0/4 — select command not parsed (only compiler stub)
relativePositionalExpression	4	—	0	0/4 — first in, last in, random in collection-relative expressions missing
reactive-properties	4	—	0	0/4 — property-reactivity runtime not present
log	4	—	4	full
resize	3	—	0	0/3 — on resize synthetic event missing
logicalOperator	3	—	0	0/3 — async-safe and/or promise propagation absent
init	3	—	1	partial
focus	3	—	0	0/3 — focus / blur commands not wired
closest	3	—	1	partial
show	2	—	2	full
measure	2	—	0	0/2 — measure command stubbed
asyncError	2	—	0	0/2 — async error propagation
settle	1	—	1	full
scoping	1	—	1	—
queryRef	1	—	0	<sel/> selector refs — tokenizer skips
objectLiteral	1	—	0	JS-object literal in hyperscript expression missing
js	1	—	1	js ... end inline JS — we parse but don't emit real JS (no JS host)
in	1	—	0	in collection op missing
cookies	1	—	0	cookies.name magic symbol missing
attributeRef	1	—	0	@attr attribute-ref expressions

Categories with 0 simple-clean coverage (highest priority): asExpression (17), splitJoin (7), pick (7), mathOperator (5), askAnswer (5), scroll (8), evalStatically (8), socket (4), select (4), relativePositionalExpression (4), reactive-properties (4), resize (3), logicalOperator (3), focus (3), measure (2), asyncError (2), queryRef (1), objectLiteral (1), in (1), cookies (1), attributeRef (1), live (23), bind (43), collectionExpressions (17).

---

3. Feature gaps (parser / compiler / runtime)

Commands

Command	tokenizer	parser	compiler	runtime	Notes
add	yes	yes	yes	yes	complete minus [@attr] / {css-block} forms (new 0.9.90 block-CSS added in b23da319 ✓)
remove	yes	yes	yes	yes	as above
toggle	yes	yes	yes	yes	inc. between and N-way cycle (commit 00bf13a2)
set	yes	yes	yes	yes	array concat form (set a to a + [1]) untested
put	yes	yes	yes	yes	most positional forms
append	yes	yes	yes	yes	landed c8aab54d
prepend	no	no	no	no	not a 0.9.90 core command — only insert before via put, ignore
transition	yes	yes	yes	yes	inc. possessives
show / hide	yes	yes	yes	yes	when clause on hide (new 0.9.90) untested
wait / settle	yes	yes	yes	yes	via perform IO suspension
send / trigger	yes	yes	—	partial	send lands in compiler dispatch; trigger alias
call / get	yes	yes	yes	partial	call functions that return promises stubbed
log	yes	yes	—	partial	behavior OK
fetch	yes	yes	yes	yes	11/23 passing; non-2xx throw + as Response + do not throw missing
throw	yes	yes	yes	yes	raise-based
continue / break	yes	yes	yes	yes	landed f200418d
return / exit	yes	yes	yes	yes	guard-based (commit 97818c6d)
halt	yes	yes	yes	yes	modes landed 922e7a78
repeat	yes	yes	yes	yes	forever, while, until, times, for-in, index
for	yes	yes	yes	yes	alias of repeat for
if / unless / else / end / then / with	yes	yes	yes	yes	unless recognized but not parsed as separate — unchanged from prior audit
js	yes	(no)	(no)	(no)	embedded JS — we can't execute JS without a JS host
go	yes	yes	yes	yes	basic go to <path>; go to the top/bottom of deprecated in 0.9.90 — replaced by scroll to
scroll	yes	yes	yes	partial	scroll to the top/bottom of — parser has 2 hits, but 0/8 simple tests pass — runtime likely does not dispatch all forms
push/pull state	no	no	no	no	history API — not in 0.9.90 core docs either
pick	yes	yes	yes	yes	landed 41cfa562; 0/7 simple — pick command needs item/char/regex runtime
render	yes	yes	—	—	parser has 8 hits but NO compiler emit — render + <template> interpolation not implemented
make	yes	yes	yes	yes	hs-make + hs-make-object
increment / decrement	yes	yes	yes	yes	full
measure	yes	yes	yes	partial	0/2 — runtime stub incomplete
tell	yes	yes	—	partial	parses, compiler handles single-cmd tell
take	yes	yes	yes	yes	full
focus	yes	yes	—	—	parser has 2 hits; no compiler emit, 0/3 simple pass
blur	no	no	no	no	0.9.90 addition, absent
hide the / show the	—	—	—	—	alt grammar variant; not tracked separately
beep!	yes	yes	yes	yes	(runtime no-op)
trim / cut / copy / paste	no	no	no	no	clipboard magic symbols + commands absent
media	no	no	no	no	not in 0.9.90 core
dialog	no keyword	yes	yes	partial	parser parses dialog-open/close forms, 5/10 simple pass; commit 802ccd23 recent
morph	yes	yes	yes	yes	landed 5b0c8569; 4/10 simple
empty / clear	yes	yes	yes	yes	landed 802ccd23
reset	yes	yes	yes	yes	landed (form reset 9d246f5c)
swap	yes	yes	—	partial	tokenizer has it; compiler dispatch missing — 4/4 simple currently pass? (verify)
open / close	yes	yes	yes	partial	dialog/details/popover/fullscreen variants
select	yes	yes	partial	partial	parser + compiler dispatch; select command 0/4 simple — runtime not complete
ask / answer	no	no	no	no	0/5 simple — new 0.9.90, absent
speak	no	no	no	no	0.9.90 addition, absent (Web Speech API)
breakpoint	no	no	no	no	0.9.90 addition, absent
view transition	no	no	no	no	0.9.90 addition, absent
intercept	no	no	no	no	0.9.90 service-worker DSL, out of scope

Expressions / operators

Expression	Status	Notes
me, my, it, its, result, event, detail, target	yes	tokenizer & parser
that	no	not in tokenizer — uncommon, low priority
element	partial	parser has 1 hit
body, document, window	no	not tokenized — high-value gap for e.g. on resize from window
you, yourself, sender	partial	you/sender tokenized, not parsed
response	no	fetch response magic — used in error handlers
clipboard, selection	no	0.9.90 additions
first/last/random in	partial	tokens; random has 1 parser hit — 0/4 relativePositionalExpression tests pass
closest	yes	1/3 simple
next, previous	yes	tokenized
parent of, children of	no	not tokenized — parent/children expressions missing
class ref (.foo), id ref (#foo)	yes	tokenizer handles
selector ref (<sel/>)	partial	tokenizer has < but not /> closer — 88 JSON tests use this
attribute ref (@attr)	yes	but [@attr] bracket form deprecated — we likely have mixed support
style ref (*prop)	yes	parser has 7 hits
CSS block ({color: red})	no	— 19 JSON tests use this
string interpolation ${...}	no	— 21 JSON tests use this
time refs (1s, 1ms)	yes	parse-duration
math + - * /	yes	via evaluator
mod	yes tok	0/5 simple — runtime doesn't propagate promises
abs	no tok	absent
floor/ceil/round	no	absent as hyperscript keywords (only via JS interop)
is / is not / ==	yes
matches / contains	yes	inc. ignore-case (ef5faa6b)
starts with / ends with	yes	parser has both with ignore-case variants
between ... and ...	yes	9 parser hits; may not cover comparison form
precedes / follows	yes	3 parser hits each
ignoring case	yes	1 tokenizer hit; needs coverage per-primitive
in / not in	yes-partial	3 tests
empty (predicate)	yes
exists	partial	dropped short-circuit (ef5faa6b); 1 parser hit
no <expr>	partial	1/5 simple
not, and, or	yes	short-circuit async missing → 0/3 logicalOperator simple
async and/or	no	0/3 logicalOperator simple; needs promise propagation
some	partial	tokenized
collection: where	yes tok	1 parser hit — 0 working simple tests
collection: sorted by / sorted by desc	yes tok	runtime hs-sorted-by / -desc present, not wired from parser for all forms
collection: mapped to	yes tok	—
collection: split by / joined by	yes tok	runtime hs-split-by / hs-joined-by present — 0/7 splitJoin simple
type conversion as Foo	partial	4/17 asExpression simple — JSONString / FormEncoded / **pipe `
pipe `	` for conversions	no
ternary / if ... else ... expression	partial	command-form only
object literal {key: val}	partial	0/1 — special parser

Event syntax / feature forms

Feature	Status	Notes
on <event>	yes	core
on every <event>	yes	hs-on-every
on <event> from <target>	yes	inc. window / document textual — but tokenizer lacks window/document
event queueing (queue all/none/first/last)	no	0 parser hits for queue — new in 0.9.90-era polish
debounced at <duration>	no	0 parser hits
throttled at <duration>	no	0 parser hits
halt the event / halt bubbling / halt default	yes	mode form in parser line 1953
on <event> when <cond>	yes	when-cond parser
on intersection / on mutation observers	no	needs IntersectionObserver/MutationObserver wiring
on resize (synthetic)	no	0/3 resize tests; ResizeObserver adapter missing
on first <event>	no	one-shot modifier
on load / init	yes	in feat parser
on <event> in <selector>	partial	delegation
behavior Name ... install <Name>	yes (parsed)	behavior parsing at line 2390+
def name(args) ... end	yes	(commit 9d246f5c)
worker	no	extension, out of scope
live feature	partial	tokenizer has live, parser 3 hits; no reactivity runtime → 0/23 live simple
bind feature	no	tokenizer + parser both 0 hits — biggest single feature gap (44 upstream tests)
when <expr> changes	partial	changes is tokenized; reactive wiring missing

Scope

Feature	Status	Notes
locals (set x ...)	yes	full
element-scope (me.x, my x)	yes	my/your alias
globals ($x)	yes
dotted names	yes
local x	partial	tokenized
DOM-scope ^var	yes	23/25 simple — strong coverage

---

4. Test complexity buckets we're NOT running

Bucket	Upstream count	Our coverage	What's missing
simple	469	~454 via behavioral (real) + ~89 stubs	15 skipped for pattern reasons
evaluate	125	0 as evaluate-typed tests; some merged into behavioral	DOM-mutation-after-eval tests — need real browser, not sandbox
run-eval	83	0 distinct	Mixed run+eval — possible via sandbox with state reads
promise	57	partial via perform	Async promise chains — we have IO suspension but no sinon stub
eval-only	39	partial	Pure expression tests — easy to add (just run eval-hs and assert result)
script-tag	36	0	<script type="text/hyperscript"> bootstrap path — we don't simulate the script-tag loader
sinon	17	0	Fetch stubs — our fetch tests mock via host-* server stubs, not sinon. 11/23 fetch pass, but the 17 sinon-specific tests aren't run
dialog	5	partial	<dialog> element's showModal() / close() — needs dialog API mock

What each bucket would need:

• eval-only and run-eval — cheapest wins. These just need eval-hs with result assertion. Missing infrastructure: none (we already have this in test-framework.sx). Gap is that the extractor tagged them eval-only so they weren't included in the "simple" migration.
• evaluate — needs DOM mutation → DOM query. Our sandbox has mock DOM so most should be portable.
• script-tag — needs script-tag loader: scan HTML for <script type="text/hyperscript">, compile and run. Separate from _= attribute bootstrap. Not hard — just a hook in integration.sx.
• sinon — needs fetch mocking per-test. We have host-* server stubs globally. Fix: extend hs-fetch mock to support per-test route registration (some already done in 673be857).
• dialog — needs HTMLDialogElement.showModal() / .close() + returnValue attribute. Minimal mock.
• promise — most already work via perform. The ones that don't involve Promise.resolve(x) wrapping in JS (call functions that return promises). Needs awaiter mock.

---

5. Pattern classes the tokenizer skips

Global JSON counts (from html + check + action concatenation):

Pattern	Upstream tests using it	Upstream feature	Our parser
[@attr="val"] bracket attribute	6	Deprecated in 0.9.90 — attribute-access/mutation syntax	tokenizer doesn't emit [@ pair — 4 add, 4 toggle, 1 remove tests skipped
${...} template interpolation	21	String interpolation in expressions and templates	Not tokenized — blocks all live/liveTemplate/render tests (~35 tests)
<sel/> selector ref	88	Inline CSS-selector reference as a value	Tokenizer has < but no closing-slash detection
{prop:val;...} CSS block	19	CSS-property block in add/remove/toggle	Tokenizer has {/} but no CSS-block parsing (partially landed b23da319 for add; not for remove/toggle)

Parser surface:

• Attribute ref @foo — yes (as expression), 1/1 simple attributeRef test still 0 pass → compiler/runtime gap
• Selector ref <sel/> — tokenizer returns "op" for /, parser has no rule to assemble as a single value
• String interp ${x} — tokenizer returns "str" but doesn't split on ${...}; no parser for expression embedding
• CSS block — tokenizer consumes {/} as punctuation; no recognition of CSS-property list inside

Recommendation:

• [@attr] — since 0.9.90 deprecated it, don't invest
• ${...} — required for live, liveTemplate, render, bind. High priority
• <sel/> — 88 tests blocked; large ROI. Tokenizer change + parser rule
• {css} — already partially done; extend to remove / toggle

---

6. Summary table

Category	Upstream	Impl (parse+compile+run)	Simple tests passing	Gap class
add	19	yes (minus [@/{css} forms)	18	skip patterns
remove	14	yes	12	skip patterns
toggle	30	yes (inc. between/cycle)	28	skip patterns
set	25	yes	24	array-concat
put	38	yes	37	complex positionals
append	13	yes	13	—
transition	23	yes	22	—
show	2	yes	2	—
hide	14	yes	14	—
wait	7	yes	7	—
send/trigger	8	yes	8	—
call	6	partial	5	promise await
fetch	23	partial	11	non-2xx throw, do not throw, pipe `
throw/catch/finally	incl. def	yes	—	—
if/unless/else	19	yes	18	—
repeat	30	yes	23	index, by step
for	—	yes	—	—
def	27	partial	3	async/catch variants
behavior/install	—	parses	—	—
init	3	partial	1	immediate init variants
increment/decrement	20	yes	20	—
take	12	yes	12	—
tell	10	partial	10	multi-stmt tell
halt	7	yes	6	—
empty/clear	13	yes	12	—
reset	8	yes	8	—
swap	4	partial-runtime	4	—
open/close	—	partial	—	dialog/popover
dialog	10	partial	5	dialog API mock
morph	10	yes	4	element-target forms
focus	3	no	0	not wired through compile
blur	—	no	—	absent
scroll	8	partial	0	runtime dispatch incomplete
measure	2	partial	0	runtime stub
pick	7	partial	0	runtime item/regex modes
select	4	partial	0	select-command runtime
bind	44	no	1	reactivity runtime
live	23	no	0	reactivity runtime
when-changes	41	partial	5	reactivity deps
reactive-properties	4	no	0	property reactivity
liveTemplate	10	no	7	${} + <template>
component	19	partial	14	custom-element register
dom-scope (^var)	25	yes	23	—
collectionExpressions	22	partial	5	where/sorted/mapped/split/joined
comparisonOperator	40	partial	4	starts/ends/between/ic async
logicalOperator	3	partial	0	async and/or
mathOperator	5	partial	0	mod/abs + async
asExpression	17	partial	0	JSONString/FormEncoded + pipe
askAnswer	5	no	0	ask/answer keywords
speak	—	no	—	Web Speech API
breakpoint	—	no	—	devtools breakpoint
intercept	—	no	—	service-worker (out of scope)
view transition	—	no	—	View Transitions API
resize	3	no	0	ResizeObserver synthetic event
bootstrap	14	partial	2	lifecycle events + cleanup()
evalStatically	8	no	0	_hyperscript.evaluate(...) static API
relativePositionalExpression	4	partial	0	first in xs/last in xs
assignableElements	8	partial	3	—
go	5	partial	3	go to the top of deprecated → scroll to
in (operator)	1	partial	0	—
no (predicate)	5	partial	1	—
closest	3	partial	1	—
cookies	1	no	0	cookies.name magic
queryRef	1	no	0	<sel/> as value
objectLiteral	1	partial	0	JS-object literal expr
attributeRef	1	partial	0	@attr as expression
js (inline)	1	parsed	1	—
splitJoin	7	runtime-only	0	parser wiring
asyncError	2	partial	0	async catch paths
parser	7	partial	3	parse-error events
scoping	1	yes	1	—
settle	1	yes	1	—

Top 5 priority gaps (by upstream test count × foundational weight)

1. Reactivity runtime (bind + live + when...changes + reactive-properties) — blocks 112 upstream tests (44 + 23 + 41 + 4). Requires: dependency-tracked evaluation, signal graph per-element, change propagation, two-way binding with dedup. Foundational: unlocks templates and components. Needs ${} string interp in parser.
2. ${...} interpolation + <template> render + #for/#if/#else control flow (render + liveTemplate) — blocks ~35 tests but is foundational for templating. Tokenizer change required (${...} inside strings); new render-command runtime; template AST with # tags.
3. Comparison + collection + conversion operator completion (comparisonOperator + collectionExpressions + asExpression + splitJoin) — 86 tests. Already have primitives (hs-split-by, hs-joined-by, hs-sorted-by, hs-starts-with-ic, etc.) but parser doesn't wire them. Lower-risk plumbing work.
4. Missing simple commands: focus/blur, scroll to, ask/answer, speak, breakpoint, select (command), measure — ~25 tests, and small per-command scope. focus/blur + scroll to alone unblocks 11 tests. ask/answer need host-prompt/host-alert/host-confirm IO effects.
5. Event syntax modifiers: queue, debounced at, throttled at, on first, on resize, on intersection, on mutation — 0 parser hits for any of these. Each is small in scope but together they affect test realism. on resize with ResizeObserver synth is the most valuable (0.9.91 bug in this area).

Secondary gaps (foundational but lower-count)

• body/document/window magic symbols — blocks on resize from window and many scroll tests. Add to tokenizer.
• parent of / children of expressions — not tokenized. Easy win.
• Pipe operator | — required for 0.9.90 chained conversions.
• fetch non-2xx throws + do not throw + as Response — 0.9.90 breaking change; 12 fetch tests blocked.
• cleanup() API + lifecycle events — needed for bootstrap suite (14 tests) and htmx 4 interop.
• Script-tag loader — 36 tests in script-tag bucket blocked for want of a <script type="text/hyperscript"> parser entry.

Non-priorities

• worker, socket, eventsource — extensions, out of scope
• intercept — service-worker DSL, out of scope
• view transition — browser API, nice-to-have
• [@attr] bracket form — deprecated upstream, don't invest
• js ... end — can't execute real JS without a JS host; we parse but can't semantically emit