feat(related): photo cards — 6 on desktop, 4 on phones, each post's own share card

Related posts were 4 text-only cards. They now carry the post's language-specific
ogImage (/og/<slug>.jpg for EN, /og/zh-<slug>.jpg for ZH), so an English page never
shows Chinese art. Grid is 3 across above 900px, 2 across below, and phones show the
first 4 only; read-time is dropped under 600px so the date fits.

Verified in the built HTML + headless Chrome at 1264/884/500px: 3/2/2 columns,
6/6/4 visible cards, no horizontal overflow, all six images decoded.

docs/design-guide.md

@@ -22,7 +22,7 @@ Read this **before** touching theme, layout, typography, color, or SEO markup. P
 - **Sticky header** — name/logo + nav (Blog / Categories / About / RSS).
 - **Article header** — title, pub date, reading time, category + tags, author card (photo, 1–2 line bio, LinkedIn + GitHub + git.hoelee.com links).
 - **Author box / ProfilePage schema** on every post (see SEO below).
-- **Related posts** (3 cards) — internal linking + keeps readers on-site.
+- **Related posts** (6 photo cards: 3 across on desktop, 2 across ≤900px, the first 4 only on ≤600px) — internal linking + keeps readers on-site. Each card shows the post's own language-specific share card, so an EN page never shows ZH art.
 - **RSS link** in footer — how the technical audience follows me.
 - **Custom og:image per post** — 1200×630, never the reused logo.
 
@@ -38,7 +38,8 @@ Read this **before** touching theme, layout, typography, color, or SEO markup. P
   |---|---|---|
   | `og:image` / `twitter:image` | **PNG** (1200×630) | Social scrapers (WhatsApp / LinkedIn / FB / Telegram) do not reliably render WebP share cards. Compatibility beats bytes here. |
   | Article banner in-page | **WebP q78** + PNG fallback via `<picture>` | 6.02 MB → 2.52 MB across 70 banners (42%); JPEG would be *larger* (q85 = 129% of PNG) because the art is flat terminal-style with sharp text edges. |
-  | List/related thumbnails | **WebP q72 at 400w + 800w** (`/og/thumb/<name>-400.webp`) | Rows display at ~398px; they used to fetch the 1200×630 PNG (~45 KB). 400w is 5.8 KB, 800w is 16.1 KB. The homepage went from ~450 KB of thumbnails to ~62 KB. |
+  | List thumbnails | **WebP q72 at 400w + 800w** (`/og/thumb/<name>-400.webp`) | Rows display at ~398px; they used to fetch the 1200×630 PNG (~45 KB). 400w is 5.8 KB, 800w is 16.1 KB. The homepage went from ~450 KB of thumbnails to ~62 KB. |
+  | Related-post cards | The post's **own share card** (`/og/<slug>.jpg`, ZH `/og/zh-<slug>.jpg`), `loading="lazy"` | The card must match the page language, and the thumb WebPs are keyed by base slug — using them would print EN art on ZH pages. 6 cards ≈ 390 KB, deferred below the fold. |
   | Real photos (author, hardware) | **WebP q82** + JPEG fallback | Continuous-tone images are the opposite case from the flat art above. |
 
   Regenerate all derivatives after adding a post: `uv run --with pillow python scripts/optimize-images.py`.

docs/project-state.md

@@ -252,6 +252,14 @@ No topics were killed by the user in this sweep.
 - Open, and **not** engineering: the round-5 consultant questions ("no text" acceptance line, banner framing, dark art on the light theme) — see the phase log.
 - ⚠ Overwriting art in place keeps the same URLs, so a returning reader sees the old picture from their own cache; hard-refresh before judging a restyle batch.
 
+### Phase G — Related-posts photo grid (2026-10-20)
+- ✅ `Related Posts` / `相关文章` went from 4 text-only cards to **6 cards carrying each post's own share card**: `ogImage` per post means the EN page shows `/og/<slug>.jpg` and the ZH page `/og/zh-<slug>.jpg` — no cross-language art. Measured in the built HTML: 6 `<img class="related-thumb">`, all 6 files 200, ZH page resolves all 6 to `zh-` files.
+- Layout: 3 across (>900px), 2 across (≤900px), and on ≤600px the same 2 columns show only the **first 4** (`.related-extra` hidden, `i >= 4` in `[...slug].astro`). Read-time span (`.related-read`) is dropped on phones so the date fits a 160px card.
+- Verified with headless Chrome by injecting the built `<section class="related">` + built CSS into a probe at 1264 / 884 / 500 px: `gridTemplateColumns` = 3 / 2 / 2 columns, visible cards 6 / 6 / 4, `scrollWidth == clientWidth` everywhere (no overflow), 6/6 images decoded.
+- ⚠ Headless `--window-size=390` is silently clamped to **500** on Windows — the right-hand column looks clipped in the screenshot, but that is the capture, not the layout. Verify <500px by putting the probe in a 390px `<iframe>` and screenshotting that.
+- ⚠ `--virtual-time-budget` can expire before lazy images paint (5 of 6 cards came out as empty `var(--border)` rectangles at budget 6000). Use ≥20000 before declaring an image broken.
+- Bytes: 6 × ~65 KB JPEG ≈ 390 KB, `loading="lazy"` and below the fold. The `/og/thumb/` WebPs (5.8 / 16.1 KB) are keyed by base slug with **no ZH variant**, so they cannot be used here without first emitting `/og/thumb/zh-<slug>-{400,800}.webp`.
+
 ### Phase A — Identity (DONE)
 - ✅ Real headshot in the About hero, the author card on every post, the home hero (EN + ZH) and JSON-LD `Person.image`; no 404 for any derivative.
 - ✅ One branding line ("Full-Stack Developer & DevOps Engineer") aligned across `SITE.title`, meta description, JSON-LD and the homepage hero.

docs/seo-reference.md

@@ -42,7 +42,7 @@ The entire blog strategy is a **name-search play**, so identity must be airtight
 - [ ] `sitemap.xml` + `robots.txt` + RSS — auto-generated by Astro
 - [ ] Core Web Vitals 90+ (verify Lighthouse on 390px **and** 1280px)
 - [ ] Question-shaped H2/H3 (the phrasing a learner actually searches)
-- [ ] Related-posts module (3 cards) on every post
+- [ ] Related-posts module (6 cards) on every post
 - [ ] No orphaned/thin pages (avoid the hoelee.com ~400-attachment mistake)
 
 ### Crawler / sitemap mechanics (as built)