fix(nuxt): security proxy prefers raw runtimeConfig/process.env strings over coerced values

[yamcodes]

Summary

The Nuxt security proxy prefers raw string sources over the coerced validation target on both the client and server branches, so coercion (ADR 0002) is silently bypassed: a key typed as number returns a raw string at runtime.

Details

In packages/nuxt/src/create-env.ts (~lines 327–372), the proxy getter resolves schema keys in this order:

• Client branch: runtimeEnv → useRuntimeConfig().public (raw strings) → __NUXT__.config.public (raw strings) → coerced target.
• Server branch: runtimeEnv → runtimeConfig[prop] / runtimeConfig.public[prop] (raw strings) → raw process.env[prop] → coerced target.

Severity on the server: prop in process.env is near-always true for schema keys (they were just validated from it), so the coerced target is effectively unreachable in the common path unless runtimeEnv explicitly owns the key. Server-side coercion is broken by default, not just in edge cases.

Fix direction

Coerce values before they enter the runtime payload rather than shipping a validator to the client. Implementation note: Nitro applies NUXT_PUBLIC_* runtime overrides as strings at boot, so the fix needs a boot-time coercion pass (e.g. a Nitro plugin), not just build-time injection.

Acceptance criteria

• A key declared with a coercing schema (e.g. "string.numeric" with coerce) returns a number on both server and client, including when overridden via NUXT_PUBLIC_* at boot.
• No validator code ships to the client bundle.
• The existing test "dynamically resolve client keys from useRuntimeConfig" is updated to assert coerced values.
• Regression tests cover the server branch's process.env fallback path.

Landing

Lands on dev first (bug fix affecting current users), then forward-port to v1 per the dual-tracking flow.

Part of #1105 (ADR 0015, #1326) — the aligned model's honesty claim is only as good as its weakest integration.

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[yamcodes]

This was generated by AI during triage.

Triage Notes

Category: bug · State: ready for agent

Reproduction — confirmed (code path): The server branch of the proxy getter in packages/nuxt/src/create-env.ts returns raw runtimeConfig[prop], then raw runtimeConfig.public[prop], then raw process.env[prop] before ever falling through to the coerced target (Reflect.get(target, prop, receiver)). Because prop in process.env is near-always true for validated schema keys, the coerced target is effectively unreachable in the common server path — matching the report. Coercion (ADR 0002) is silently bypassed and a number-typed key returns a raw string.

Acceptance criteria in the issue body are sufficient as the agent brief. Note the landing flow: dev first, then forward-port to v1.

[yamcodes]

This was generated by AI during triage.

Scope clarification: The acceptance criterion “No validator code ships to the client bundle” (and the Nitro boot-time coercion pass for NUXT_PUBLIC_* overrides) is tracked as v1 work in #1424, not as part of this dev-first proxy preference-order fix.

This issue remains: prefer the coerced validation target over raw runtimeConfig / process.env / __NUXT__ strings on get.