ADFA-4128 (11/11): app + bench — wiring Quick Build into the IDE and the benchmark harness

[fryanpan]

Part 11/11 of the stacked split of #1669 (requested by Akash). Base: feature/ADFA-4128-qb-10-gradle-plugin. Stack overview + review mechanics: PR 1 (#1713). Terms are defined in quickbuild/README.md (lands in PR 1).

Puts Quick Build in front of the user: a button next to Run, and enough narration to tell what it is doing and when it has finished. It also adds a harness to make it easier to run standard Gradle build and Quick Build benchmarks, and to gather key metrics about the stages of the build process.

flowchart TB
    subgraph appc["<b>This PR: inside app/ — wiring and bench</b>"]
        act["QuickBuildAction<br/>registered only when<br/>FeatureFlags.isExperimentsEnabled<br/><i>QuickBuildAction.kt</i>"] --> mgr["QuickBuildManager<br/>session lifecycle, provisioning,<br/>stop-tap cancellation"]
        mgr --> narr["QuickBuildOutputNarrator<br/>attached to the session manager;<br/>queues while no pane is bound<br/><i>QuickBuildOutputNarrator.kt</i>"]
        mgr --> sb["status bar collector<br/>lifecycle-scoped: state, not history<br/><i>QuickBuildStatusBar.kt</i>"]
        koin["QuickBuildModule (Koin)<br/>binds every core port;<br/>assetsLiveReloadable read once<br/>at the Android edge<br/><i>QuickBuildModule.kt</i>"]
        tr["bench trampoline activity<br/>debug-source-set manifest only<br/><i>QuickBuildBenchActivity.kt</i>"] --> mgr
        mgr --> hooks["QuickBuildBenchHooks<br/>inert release twin<br/><i>debug/QuickBuildBenchHooks.kt</i>"]
        hooks --> rec["event + metrics recorders"]
        rec --> log["bench-events.jsonl<br/><i>BenchEventsFile.kt</i>"]
        hooks --> e2e["MODE_STANDARD_E2E<br/>measures the standard build<br/>through install + launch<br/><i>QuickBuildBenchAutostart.kt</i>"]
    end
    adb["adb shell am start<br/>gated on android.permission.DUMP"] --> tr
    mgr --> core[":quickbuild:core session manager (PRs 5-8)"]
    narr --> pane["Build Output pane (existing)"]
    sb --> bar["bottom status bar (existing)"]
    mgr -- "provisioning + rebuild builds" --> gbs["GradleBuildService (existing)"]
    classDef thisPrBox fill:#dbeafe,stroke:#93c5fd,color:#1e3a5f
    classDef inPr fill:#ffffff,stroke:#64748b,color:#000
    class appc thisPrBox
    class act,mgr,narr,sb,koin,tr,hooks,rec,log,e2e inPr

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What to review

• QuickBuildAction.kt — owns the session tap: start, stop-tap cancel, grey-out. Line-by-line.

• Gradle tuning — Metaspace 192→384 MB + daemon idle timeouts (30 min balanced / 2 h high-perf); the only changes to non-QB behavior

• QuickBuildOutputNarrator.kt, QuickBuildStatusBar.kt — queued narration; lifecycle-scoped status showing state, not history.

• QuickBuildModule.kt — binds every core port; reads assetsLiveReloadable at the Android edge.

• GenerateSourcesDeferral.kt — defers resource-XML generateSources until Quick Build goes idle.

• John's items C15, C16, C17, C22, C23 folded in as fixes.

• Rollback: without the flag there is no UI entry point.

• Followup, not fixed: R8 emits kotlin.Metadata warning noise.

• QuickBuildBenchAutostart.kt — MODE_STANDARD_E2E measures the standard build through install and launch. Line-by-line.

• The e2e latch bypasses install confirmations only for the measured span.

• QuickBuildBenchActivity.kt, QuickBuildBenchHooks.kt — DUMP-gated trampoline; inert release twin.

• BenchEventsFile.kt — a failed relaunch omits relaunchOk rather than recording zero.

How this PR Was Tested

• Automated tests (see coverage details below)

• Manual QA — walked the manual-qa.md test plan on the A56 [measured on a56]

• Benchmark — full two-device pass (2026-08-22; 35-app corpus, 160 scripted edits; both arms on real devices): a warm code edit reaches the running app 5.4x faster than a standard build + deploy on a Samsung A56, and 7.3x faster on a low-spec A06 — the weaker the phone, the bigger the win. Medians over 87 / 82 paired edits, with the standard arm's install-dialog wait already subtracted, so the numbers are conservative. MODE_STANDARD_E2E drove the standard arm through install + launch on both devices during this pass.

• Still open — the rebaseline relaunch metric (its column never populated; a dedicated bench is deferred), and the API 28/29 resource-swap success path.

Coverage (JaCoCo at the stack tip, single run):

A lot of this was UI code and wasn't covered very well by automated tests.

Package	Line	Branch	Note
actions/build	0.5%	0.0%	UI — device-tested
actions/file	0.0%	0.0%	UI — device-tested
activities/editor	0.9%	1.8%	UI — device-tested
analytics/quickbuild	49.6%	30.4%
app	0.7%	0.5%	Application classes, Android-bound
di	0.0%	0.0%	Koin wiring
fragments/sidebar	0.0%	0.0%	UI — device-tested
handlers	7.6%	0.0%	Android-bound
quickbuild	27.3%	24.3%	mixed UI/logic; see caveat
services/builder	6.8%	0.0%	bound Service, Android-bound
utils	0.0%	0.0%	mixed UI/logic
viewmodel	0.9%	0.0%	UI — device-tested
TOTAL (all app files in this PR)	16.9%	15.3%	2,989 lines, 1,582 branches

Review fixes (2026-08-22)

A review-fixes commit addresses the code-review findings. Two changes here deliberately ship to all users, with the Experiments flag off (approved):

• GradleBuildTuner. Benefit: builds stop dying with out-of-memory errors on ordinary phones, and a rebuild shortly after a build is much faster. Two settings on every Gradle build: (a) the Metaspace cap (JVM memory for loaded class definitions) goes 192 MB -> 384 MB -- real Android-plugin builds exceed 192 and were being killed mid-build; it's a cap, not a reservation, so no extra memory is used unless the build needs it. (b) The Gradle daemon (the background process that keeps builds warm) stays alive for a time matched to the phone's tier -- 15 min low-memory, 30 min balanced, 2 h high-performance -- so a quick rebuild skips the cold start while weak phones don't host a resident daemon for hours.
• generateSources narrowing. Benefit: fewer surprise build stalls while editing, less battery and CPU burned. The IDE used to launch a Gradle generate-sources step after every save-all and any XML save, even when nothing that step produces could have changed. Now it runs only when the saved file can actually affect generated sources. Same results, far fewer builds.

One candidate followup from review (orchestrator forcing a full-changed compile after a failed dex/deploy) was re-checked and refuted at this tip: the forced flag re-arms and a forced no-op already performs the full rebuild. The daemon-side recovery lever stays in as defense in depth.

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