build: prevent Oxygen deploy OOM on large storefronts (disable prod sourcemaps + doc heap fix)

[paul-phan]

Why

A client storefront built on this theme hit FATAL ERROR: JavaScript heap out of memory (exit 134) during the Oxygen deploy. The production build peaked above the CI runner's default Node heap (~2GB), so the deploy died before uploading a complete build. The environment then served HTML referencing client JS assets that were never published, and the storefront rendered blank (all oxygen-v2/.../assets/*.js returned 404).

To avoid other clients hitting the same wall on large storefronts, harden the base theme.

Changes

1. vite.config.ts — build.sourcemap: false. Sourcemap generation is a major memory driver during the production build; disabling it lowers peak memory with no runtime cost.
2. README.md — document the heap fix (NODE_OPTIONS: --max-old-space-size=8192 on the Oxygen deploy step) for storefronts large enough to still OOM. The deploy workflow is generated per-storefront by Shopify, so this can't live in the theme repo, but the note tells clients exactly where to add it.

Notes

• manualChunks splitting is already present in this config and is kept.
• No behavior change at runtime; sourcemaps were only used for build-time debugging.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Disable server sourcemaps in Hydrogen deploys

When the Oxygen workflow uses npx shopify hydrogen deploy, this setting does not disable the expensive server sourcemap build: the installed Shopify CLI's deploy path calls its build helper with sourcemap: true, and that helper passes an inline Vite config for the SSR build (build: { sourcemap: n, ssr: ... }), which takes precedence over vite.config.ts. Large storefront deployments will therefore still generate SSR sourcemaps and can still hit the OOM this commit is meant to avoid unless the deploy uses a custom build command/flag that turns Hydrogen sourcemaps off.

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[paul-phan]

Closing in favour of #469.

Built Pilot both ways to check this. The vite.config.ts change here is a no-op:

main (no PR):     dist/server/index.js.map  4,833,304 bytes
this PR applied:  dist/server/index.js.map  4,833,304 bytes
cmp → byte-identical

Two independent reasons:

1. build.sourcemap already resolves to false on main for both the client and SSR passes. That's Vite's default, so this sets a value to what it already was.
2. The Shopify CLI overrides the config file anyway. The server build gets sourcemap inline and deploy hardcodes it: await Je({ ..., sourcemap: !0, forceClientSourcemap: d, ... }) in @shopify/cli/dist/chunk-AATUQ2AY.js. Inline config beats the config file in Vite.

The working lever is the CLI's own flag:

Build	server output	.map files	peak RSS
default	6.9 MB	1	1362 MB
SHOPIFY_HYDROGEN_FLAG_SOURCEMAP=false	2.3 MB	0	1136 MB

The NODE_OPTIONS half of the README note was right and carries over to #469. The claim that sourcemaps are 'already disabled in vite.config.ts' did not, since it would send the next person debugging an OOM down the same dead end. The stray empty ## Getting started heading is dropped too.