Type the render client: no implicit any, no implicit this

[Alek99]

Stacked on #159 (base: feat/ts-vite-client). Merge that first.

What

Turns the TypeScript conversion from "compiles" into "typechecked". 2321 diagnostics → 0 under the newly enabled flags:

noImplicitAny  noImplicitThis  strictFunctionTypes  strictBindCallApply
noImplicitReturns  noFallthroughCasesInSwitch  useUnknownInCatchVariables

Every parameter, local, and this in the client is now typed — no value acquires any implicitly. tsc already gates every build (js/build.mjs runs it first, since oxc strips types without checking them), so this is enforced on every PR.

How

• js/src/05_types.ts (new) carries the wire contract the kernel emits: ChartSpec, TraceSpec, AxisSpec, ChannelSpec, ColumnMeta, GpuTrace, Hit, Row, Comm, TickResult, Theme, MarkKind, Rgba. Deliberately permissive where the wire is permissive — open index signatures stay, because tightening one is a compatibility decision to make alongside the Python that emits it.
• as ThisType<ChartView> on the prototype-augmentation literals (51–57) types this as ChartView instead of the object literal. That one type assertion resolved 1190 of the 2321 diagnostics, and erases at compile.
• Per-module types where no shared name fits: LOD drill/density updates, animation easings and transition records, view-state patches and durable state, interaction option bags, GL program/buffer tags (XyProgram, XyBuffer), ColumnView, AxisMap.
• _listen became generic over its event type so call sites keep precise handlers (PointerEvent, WheelEvent, …) under strictFunctionTypes.

Types-only — proven, not asserted

The committed minified bundles in python/xy/static/ are byte-identical before and after this change; the diff contains no bundle. Independently, three of the workers transpiled HEAD vs. working copies and byte-compared the emitted JS per file.

That check earned its keep twice: it caught a && → ?. rewrite that had slipped into a catch-narrowing fix, and a case where an interface placed above the first runtime statement absorbed a file's header comment and changed emit.

Verification: tsc clean · bundles byte-identical · full pytest 2208 passed · render smoke XY_OK with pixel counts and context-loss hashes identical to the pre-typing run · ruff + pre-commit clean.

Test fallout

Source-marker tests that grep exact client signatures are updated to the typed forms, preserving their parameter-contract intent. Separately, tests/reflex_adapter/test_assets.py still grepped unminified markers (function renderStandalone() — it only runs when reflex is installed, so it was missed when the bundles began shipping minified in #159. Fixed here to use the same export-alias contract verify_wheel.py asserts.

Latent bugs surfaced (reported, not fixed — types-only)

Typing the code found real issues. None are touched here; each deserves its own change:

1. lodApplyDensityUpdate reads g.density.colormap/.color/.lut unguarded, while every sibling access guards — a density update on a trace whose density was never built is an uncaught TypeError.
2. RECT_MARK/BAR_MARK/SEGMENT_MARK/AREA_MARK/line dereference g.trace.style.color unguarded; style is optional on the wire (MESH_MARK and hexbin do guard).
3. 54_kernel builds pendingTraceIds with Number(upd.id) but tests membership with the raw g.trace.id; TraceSpec.id is string | number, so a string id silently skips the clearPending sweep.
4. _onA11yKey computes hit.trace * 1e9 + hit.index from a trace id; a string id makes _hoverId NaN and every !== -1 guard read true forever.
5. 51_annotations liftBounds.width is only safe via a two-expression short-circuit that a future edit could split.
6. 57_viewstate canBandPan() returns truthy via _axisContained even when pan policy excludes the axis — possibly deliberate, worth a look.

Items 1, 2, and 5 are exactly the class strictNullChecks would catch, which motivates the order below.

Deferred (documented in js/tsconfig.json)

1. Remove ChartView's [key: string]: any. It is what still lets this.typo compile and what stops the annotated signatures in 51–57 from being enforced at call sites. Needs ~403 declared members (172 class methods, 119 augmentation methods via declare module merging, 112 instance fields) — mechanical, but its own reviewable PR.
2. strictNullChecks — largest remaining win, largest diff.
3. strict: true once 1 and 2 land.

[codspeed-hq]

Merging this PR will not alter performance

✅ 97 untouched benchmarks
⏩ 1 skipped benchmark¹

---

_{Comparing feat/ts-strict-client (99cadae) with feat/ts-vite-client (6caeeb0)}

Footnotes

1. 1 benchmark was skipped, so the baseline result was used instead. If it was deleted from the codebase, click here and archive it to remove it from the performance reports. ↩

[greptile-apps]

Greptile Summary

This PR adds full implicit-type checking to the TypeScript render client. The main changes are:

• Shared types for the kernel wire contract and render state.
• Explicit types for client functions, callbacks, events, and prototype methods.
• Stronger TypeScript compiler checks in the client build.
• Updated source and bundle contract tests for typed and minified output.

Confidence Score: 5/5

This looks safe to merge.

No blocking issues found in the changed code.

T-Rex Logs

What T-Rex did

• Ran the TypeScript typecheck proof and confirmed it completed with exit code 0, validating the TypeScript step of the render-client workflow.
• Ran the render-client bundle freshness proof and confirmed it completed with exit code 0, validating the bundle freshness check.

_{Ran code and verified through T-Rex}

Important Files Changed

Filename	Overview
js/src/05_types.ts	Adds permissive shared declarations for wire data, rendering state, communication, and mark implementations.
js/src/45_lod.ts	Adds explicit types for LOD windows, density payloads, drill updates, and GPU cache helpers.
js/src/50_chartview.ts	Types ChartView construction, context management, events, view state, rendering helpers, and dynamic members.
js/src/60_entries.ts	Types the public rendering entry points while preserving runtime exports and prototype side effects.
js/tsconfig.json	Enables implicit-type, callback variance, bind/call, return-path, fallthrough, and catch-variable checks.
tests/reflex_adapter/test_assets.py	Changes installed-bundle checks to use stable minified export aliases.
tests/test_static_client_security.py	Updates source markers to match explicit TypeScript signatures while preserving the existing contracts.

_{Reviews (1): Last reviewed commit: "Type the render client: no implicit any,..." | Re-trigger Greptile}

[Alek99]

Docs verification passed on 99cadae3cfbbc59de0b63ce09145351154600259.

• docs/app suite: 72 passed, 1 expected xfail
• Production docs build completed successfully.
• Sitemap, Markdown-asset, and generated-HTML route validators passed.
• All 57 published /docs/xy sitemap routes returned HTTP 200 from the production server.
• Browser smoke test rendered the landing page’s interactive charts (12 canvases) with no console errors.

The PR changes only the typed render client; the documentation site remains healthy.