[leehack]

Summary

Prepares llamadart and the three Apple runtime companions at 0.19.8 for release plan #1959. Merging into main publishes core 0.19.8, then the three companions; it needs the maintainer's explicit go-ahead. Draft: not for merge, tag or publish until the maintainer says so. The release-prep label is set because the branch name is not a versioned release-prep name; merging triggers release_on_prep_merge.yml.

Base: main 63fb1ec0c6.

Production-readiness scope

• User-facing scope: release metadata and docs. Changes since 0.19.7: #1956 (Qwen3.5 constrained JSON with a thinking budget, #1953), #1962 (Seed-OSS required call, #1958), #1964 (WebGPU, #1954) and the tooling and test sweeps #1960, #1961, #1963 and #1965.
• Runtime pins: WebGPU bridge assets v0.1.83 -> v0.1.84 (manifest SHA-256 55abeb377597148156059a8ee5400f2314c6254ad91b57db65b709e304c0dea0, bridge dc359398, native v0.9.0). Unchanged: native llama.cpp v0.9.0, LiteRT-LM v0.19.1-4, stable-diffusion v0.3.0-3, Web LiteRT-LM @litert-lm/[email protected].
• Changelogs (core and docs): ## Unreleased becomes ## 0.19.8: an "Aligned ... v0.1.84" WebGPU line, one fixed bullet (grammars stay applied through a budgeted thought: an eager grammar that takes the forced-open thought stays applied, every other grammar pauses; Qwen3.5: constrained JSON with a thinking budget ignores the grammar after the forced </think> #1953 and Seed-OSS: required tool call unconstrained after a thinking budget (template doesn't open the thought) #1958) and the runtime baseline. Sweep, test and tooling changes have no bullet. Granite and Ling are not claimed (#1966). Released sections untouched; the docs page keeps 0.19.x and 0.18.x.
• Companions: all three 0.19.7 -> 0.19.8 (README install snippets name core ^0.19.8; companion changelogs gain a 0.19.8 section). llamadart_litert_lm_flutter core constraint >=0.19.7 <0.20.0 -> >=0.19.8 <0.20.0, same shape as 0.19.7 (#1951); the other two keep >=0.19.0 <0.20.0. Package.swift pins unchanged. genkit_llamadart and llamadart_model_store untouched.
• Supported platforms/paths / unsupported paths: unchanged by this PR; WebGPU needs assets v0.1.84+ for a grammar to stay applied through a budgeted thought, older assets throw LlamaUnsupportedException.
• Out of scope / follow-ups (tracker cleanup after merge, done by the maintainer):
  • Close 0.19.8 tracker #1950 and plan #1959.
  • Carry the 3 open 0.19.8 audit follow-ups #1950 boxes (the LiteRT-LM bundle-template e2e family skip, #1930 streaming partial parses, and the #1965 audit item) plus #1966 into a new 0.19.9 tracker.

Completeness checklist

• Declared scope is implemented.
• Unsupported combinations: N/A, no code change.
• README, installation docs, companion READMEs and the changelogs updated.
• Regression coverage: release gates pass.
• Validation coverage registry: N/A (no capability change).
• Security review: no secrets, tokens or signed URLs.
• Follow-ups: tracker cleanup above.

PR type guidance

• Release preparation: versions, install snippets, lockfiles, changelogs and the LiteRT-LM companion's core constraint. No .gitattributes change; union merge was switched off locally for the two changelogs and they were edited directly, no merge or rebase.
• Feature PR / Bugfix PR / Docs-only PR: N/A.

Test Plan

Pinned Flutter 3.47.1, isolated TMPDIR.

• dart run tool/prepare_workspace.dart (plus dart pub get in packages/llamadart_validation and website/examples/observability): locks changed only for local core/companion 0.19.7 -> 0.19.8.
• dart format --output=none --set-exit-if-changed .: 0 changed.
• dart analyze: no issues.
• dart test -p vm test/unit/tooling/: all 1,742 pass. Markdown suites from tool/ci/markdown_test_suites.txt: pass.
• Full dart test -p vm / -p chrome: left to CI (no lib/ or test change in this PR).
• coverage-lib: N/A, no lib/ change.
• Other checks:
  • verify_release_docs_versions.dart and --release-prep: exit 0, "llamadart 0.19.8, llamadart_llama_cpp_flutter 0.19.8, llamadart_litert_lm_flutter 0.19.8, llamadart_stable_diffusion_flutter 0.19.8; checkout llamadart-native v0.9.0."
  • check_webgpu_bridge_tag.dart --verify-manifest: OK (16 pins agree on v0.1.84; immutable release publishes the approved manifest bytes).
  • companion_pub_preflight.dart: OK for all three companions. check_core_archive.py: passed. ./tool/docs/build_site.sh: builds.
  • Classifier (origin/main...HEAD): high-risk (artifactConsumer).

Matrix Evidence

Matrix row	Scope covered	Platform / model / backend	Result	Evidence / notes
high-risk-exact-head-independent-qa	exact-head release audit	macOS	PASS	Fresh auditor at 8fee1f5. Every gate exits 0, including --release-prep, the companion preflight, the core archive and the pub publish --dry-runs. Mutants M1-M7 are killed. Evaluator exit 2.
release-metadata-verification	versions, constraints, changelog promotion	macOS host	PASS	--release-prep exits 0.
release-doc-version-consistency	install docs, companion bumps	macOS host	PASS	verifier, both modes, exit 0.
release-companion-pub-gate	companion pub.dev availability and constraints	macOS host	PASS (pre-merge)	companion_pub_preflight.dart OK.
genkit-release, android-release-device-pool, release-representative-smokes	N/A	N/A	N/A	Genkit untouched; no runtime-code change; smokes belong to the publish step.

Review Notes

• Independent review status: PASS (fresh auditor at 8fee1f5, 0 P1/P2; P3s in 0.19.9 audit follow-ups #1967)
• CI status / head SHA: green (36 pass, 9 skipped) / 8fee1f5

High-risk regression review

• Classification: high-risk (artifactConsumer)
• Implementation task: lane-0198-prep
• Independent blocking QA task: fresh auditor, PASS. Tag v0.19.8 and all four packages at 0.19.8 are absent from origin and pub.dev. Evaluator exit 2.
• Exact head / current base: 8fee1f5 / 63fb1ec0c6
• Production-branch deletion, bypass, or miswire proof: N/A (metadata only)
• Affected-family real-model/artifact evidence: N/A
• Explicit unavailable-family or other N/A evidence: N/A
• Known PR-caused P1 regressions: 0
• Unresolved review threads: 0

[github-actions]

Chat app preview removed for leehack/llamadart-chat-pr-1968.