Build failure: missing export 'blog' from @/.source

[devrel-droid]

What this PR does

Closes #3900: Build failure: missing export 'blog' from @/.source

Now I have a complete picture. Here's my structured implementation plan:

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Implementation Plan: Fix blog Missing from @/.source

Root Cause Analysis

The trigger commit (d552c59d) only changed utils/remote-content/apis.mts (a URL fix for C-Chain RPC docs). It did NOT change source.config.ts or lib/source.ts. The build failure is a pre-existing issue that was just exposed/surfaced by this deployment.

The real cause: The project uses Zod v4.3.5 ("zod": "^4.1.12" in package.json, confirmed in yarn.lock). In Zod v4, z.string().date() returns a ZodStringFormat type (not a plain ZodString). ZodStringFormat does not have the .or() method that ZodString had in Zod v3.

Line 81 in source.config.ts:

date: z.string().date().or(z.date()).optional(),

This throws TypeError: z.string().date().or is not a function at runtime when fumadocs-mdx executes source.config.ts to generate .source/index.ts. Because blog is the last collection in the file, all preceding exports (docs, meta, course, courseMeta, integrations) succeed, but blog is silently dropped.

Why course (line 38) still works: z.string().or(z.date()) uses plain z.string() which returns ZodString — this type retained .or() in Zod v4. Only the chained .date() version is affected.

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Files to Modify

File	Change Type
source.config.ts	Fix Zod v4 compatibility in blog schema

No other files need changes. lib/source.ts is already correct.

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Step-by-Step Approach

Step 1 — Fix source.config.ts (the only required change)

In the blog collection definition (lines 75–84), replace the Zod v3-style .or() chain with the Zod v4-compatible z.union():

// Before (line 81) — broken in Zod v4:
date: z.string().date().or(z.date()).optional(),

// After — works in both Zod v3 and v4:
date: z.union([z.string(), z.date()]).optional(),

Note: The .date() string format

Here is the verification write-up:

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Summary

The build failure was caused by a Zod v4 compatibility break in source.config.ts. The project uses Zod ^4.1.12, but the blog collection's date field used the Zod v3 API z.string().date().or(z.date()). In Zod v4 z.string().date() no longer exists, causing source.config.ts to fail at schema compilation. When fumadocs-mdx could not process the config, it omitted the blog export from the auto-generated .source/index.ts, producing the 'blog' is not exported from '@/.source' error that broke the build.

The fix is a one-line change: replace z.string().date().or(z.date()).optional() with z.union([z.iso.date(), z.date()]).optional(), which is the Zod v4-compatible equivalent.

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How to verify

1. Build succeeds

The most direct check — the build must complete without the import error:

yarn build:remote && next build

Expected: no Import error: 'blog' is not exported from '@/.source'. The build should reach the static-page generation step and finish successfully.

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2. Blog listing page loads

Visit the blog index on the deployed site:

https://build.avax.network/blog

Expected: The page renders a list of blog posts (28 posts currently exist in content/blog/). Before this fix, the entire site would 500/fail to compile, so this page would not load at all.

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3. Individual blog post with a date field renders correctly

The schema change specifically affects the date field. Test a post that has an explicit date frontmatter value:

https://build.avax.network/blog/builder-console-safe-support

Expected: Page renders without error. The post has date: 2025-10-01 in its frontmatter — this is an ISO date string that z.iso.date() must accept.

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4. /api/latest-blogs returns valid JSON

This API route sorts posts by date and returns the two most recent:

curl -s https://build.avax.network/api/latest-blogs | jq .

Expected

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Self-review: issues found and fixed | QA: passed
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