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fix: settle router pending UI during navigation commits - #491

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Mohamed Mansour (mohamedmansour) merged 1 commit into
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mohamedmansour-verify-route-pending-cleanup
Aug 26, 2026
Merged

Mohamed Mansour (mohamedmansour) merged 1 commit into
mainfrom
mohamedmansour-verify-route-pending-cleanup

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Why

Router-owned pending UI was tied to partial-response completion instead of the route DOM commit. That could remove the indicator before component loading and route loaders finished, and it made terminal cleanup ordering vulnerable to stream-cancellation stalls and synchronous custom-element re-entry.

What changed

  • Keep pending UI mounted through all pre-commit work.
  • Settle the generation-owned boundary at the start of the synchronous DOM commit, before route mutations and webui:route:navigated.
  • Clear pending UI before awaiting deferred-stream cancellation on abort and failure paths.
  • Reject stale or re-entrant cleanup so an older navigation cannot mutate DOM owned by a newer one.
  • Skip pending timer setup for keep-alive destinations.
  • Add browser coverage for two consecutive parameter navigations that reuse the same component and assert zero pending nodes inside each commit and navigation event.
  • Update the routing specification and developer documentation.

Performance

Production minified ESM size:

Metric Before After Delta
Raw 37,555 B 37,800 B +245 B
Gzip 11,866 B 11,941 B +75 B
Brotli 10,692 B 10,779 B +87 B

The boundary lifecycle microbenchmark remained within measurement noise: 1.7562 ns median before and 1.7706 ns after. The implementation adds no DOM scans or per-navigation allocations.

Validation

  • pnpm --dir packages/webui-router test
  • cargo xtask check

Keep router-owned pending UI visible through pre-commit work, then remove it atomically before settled route DOM mutations. Guard cleanup by navigation generation and cover consecutive same-component commits.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
@mohamedmansour
Mohamed Mansour (mohamedmansour) merged commit 91ced51 into main Aug 26, 2026
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@mohamedmansour
Mohamed Mansour (mohamedmansour) deleted the mohamedmansour-verify-route-pending-cleanup branch August 26, 2026 04:56
Mohamed Mansour (mohamedmansour) added a commit that referenced this pull request Aug 26, 2026
## Release

Bumps WebUI to `0.0.26`.

Previous release tag: `v0.0.25`

## Changes since `v0.0.25`

Features:

- Python hosts now have an official typed PyO3 renderer package with
buffered, partial, template, token, and host-driven streaming APIs
(feat: add official Python renderer package #453 by @mohamedmansour).
- Progressive SSR can place transport-flushed streaming boundaries
inside reusable components while preserving component ownership and
continuation state (feat: support component-local streaming boundaries
#460 by @mohamedmansour).
- Components can defer compiler-owned hydration until interaction, with
router preload handoff and a combined lazy-render policy (feat: add
compiler-driven interaction hydration #485 by @mohamedmansour).
- Builds can opt into global Light DOM CSS while preserving explicit
authored Shadow roots and deterministic style closures (feat: make Light
DOM a global CSS opt-in #429 by @mohamedmansour).
- State projection supports application-owned TypeScript 7.0.2 while
retaining the TypeScript 6 migration path (feat: support TypeScript 7
projection compilation #452 by @mohamedmansour).
- WebUI Press supports layout-scoped compile-time named regions with
fallback HTML, state, components, and scripts (feat(press): add
compile-time named regions #484 by @mohamedmansour).
- FAST v2 and v3 gain plugin-owned local and npm component discovery
with validated FAST template transformation (feat: add plugin-owned FAST
component discovery #378 by @janechu).

Fixes:

- Missing condition identifiers are treated as falsy before negation and
logical evaluation, aligning SSR with the browser runtime (fix: negate
missing condition paths correctly #449 by @mohamedmansour).
- FAST route state now scales through escaped scalar kebab-case
attributes shared by FAST v2 and v3 (fix: scale FAST route state with
scalar attributes #450 by @janechu).
- Dynamic Link-mode components wait for native stylesheet readiness
across navigation and component assets, preventing unstyled flashes
(fix: prevent dynamic component stylesheet flashes #454 by
@mohamedmansour).
- Authored component definitions defer whenever compiled template
metadata has not arrived, including ordinary router navigation (fix:
defer authored define() whenever template metadata is missing #461 by
@mohamedmansour).
- Client structural updates preserve authored order and sibling
ownership for shared slots and raw HTML ranges (fix: preserve source
order for shared structural slots #465 by @mohamedmansour, fix: preserve
siblings around raw HTML updates #466 by @mohamedmansour).
- Native-element attributes no longer leak into the local state of a
later component (perf(handler): stop native attributes leaking into
component state #469 by @mohamedmansour).
- Templates-and-state-only SSR bootstrap payloads no longer require
component style metadata (fix: allow SSR bootstrap without component
styles #475 by @mohamedmansour).
- The high-level Rust `serve_request` path now preserves complete render
options, including CSP nonces, while sharing the same entry and request
path with partial rendering (fix: forward CSP nonces through
serve_request #488 by @mohamedmansour).
- Projection compilation bounds source reads, excludes binary and
unsupported-loader inputs from semantic analysis, and preserves
deterministic cleanup under large esbuild graphs (fix: bound projection
adapter source reads #489 by @mohamedmansour).
- Router pending UI remains mounted through pre-commit work and settles
at the synchronous DOM commit, with stale, aborted, and re-entrant
navigation cleanup kept generation-safe (fix: settle router pending UI
during navigation commits #491 by @mohamedmansour).

Docs:

- The documentation site adds accessible responsive navigation, improved
reading layouts, stronger search behavior, and Playground recovery
states (feat: polish WebUI documentation experience #459 by
@mohamedmansour).
- Slot-resolution implementation guidance now documents pre-order
lookup, pending placement ownership, and marker handling (chore: clarify
slot resolution comments #471 by @mohamedmansour).
- Repeated `w-ref` behavior is now explicit: refs are scalar and the
last wired occurrence wins, while stable authored IDs or item components
provide identity-based lookup (chore: clarify repeated w-ref behavior
#490 by @mohamedmansour).

Maintenance:

- Release and package policy metadata now constrains the transitive h2
advisory, uses SPDX NuGet licensing, and classifies publishing jobs
correctly (chore: allow constrained h2 advisory #451 by @janechu, fix:
use modern NuGet license metadata #457 by @janechu, chore: mark
publishing jobs as release jobs #458 by @janechu).
- The development and CI Rust toolchain is updated to 1.98 with the
resulting warnings resolved (Update rust toolchain version and fix
clippy warning #462 by @telecos).
- Release builds use Thin LTO to retain cross-crate optimization with
faster linking (perf: switch release builds to Thin LTO #464 by
@mohamedmansour).
- Handler and expression hot paths reduce attribute vtable calls, render
lookup and scope allocations, and single-term condition overhead
(perf(handler): centralize HTML attribute writing in ResponseWriter #467
by @mohamedmansour, perf(expressions): fast-path single-term conditions
#470 by @mohamedmansour, perf(handler): reduce render lookup and scope
allocations #472 by @mohamedmansour).
- Node rendering can reuse immutable prepared-state snapshots and
bounded per-route output capacity hints (perf(node): reuse prepared
state across renders #477 by @mohamedmansour, perf: reuse Node render
output capacity #478 by @mohamedmansour).
- Framework hydration releases bootstrap data sooner and reduces
allocations for bindings, empty hosts, and visible conditionals (perf:
reduce framework hydration allocations #479 by @mohamedmansour, perf:
release SSR bootstrap memory after hydration #480 by @mohamedmansour,
perf: reduce empty template host overhead #482 by @mohamedmansour, perf:
remove visible conditional anchors #483 by @mohamedmansour).
- Benchmark tooling now renders the full contact workload, runs
Criterion baselines per target, and restores the streaming hydration
fixture (fix(bench): render contacts in contact-book benchmark #468 by
@mohamedmansour, fix(xtask): run Criterion benchmarks per target #473 by
@mohamedmansour, fix: repair streaming hydration benchmark fixture #476
by @mohamedmansour).

## Validation

- `cargo xtask check`

---------

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
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