Design stale badge with replace-or-keep for projections and includes

Extend authoring model: generate alternative current version, keep or replace.
Unify with pinned transclusions/pipelines; document markitect-tool gap and
point at cross-repo proposal.

docs/architecture/authoring-modes-and-lazy-projections.md

@@ -170,9 +170,29 @@ Notes:
 
 UI: per-field overflow (✎ edit · ↻ regenerate · 🔒 lock) on cards and page chrome — unobtrusive, always available.
 
-### Staleness (optional, unlocked derived only)
+### Staleness and alternatives (default: badge + explicit choice)
 
-If `source_hash` ≠ current body hash, UI may show “metadata may be outdated” and offer regenerate — **never** auto-regenerate locked or `user` fields without consent. Policy for `derived` + stale can be: badge only (default) or auto-refresh if product later opts in.
+If `source_hash` ≠ current body/deps hash (or recipe version policy says so):
+
+1. Show **May be stale** on the field (and optionally on the card).  
+2. **Never** auto-overwrite locked or `user` values; do not auto-overwrite  
+   unlocked `derived` without consent (default).  
+3. Primary actions from the badge:
+   - **Generate updated version** → compute **alternative** (side-by-side with **current**)
+   - **Keep current** → dismiss compare; optional **ack** (update fingerprint only, clear badge until inputs change again)
+   - **Use alternative** → **replace** stored value with alternative; refresh hash/timestamps; state → `derived`
+   - **Edit** / **Lock** as usual
+
+```text
+[May be stale]
+   → Generate updated version
+        Current | Alternative
+        [ Keep current ] [ Use alternative ] [ Cancel ]
+```
+
+This is the same interaction grammar as for **pinned includes and pipeline  
+blocks** — see `stale-derived-content.md` and markitect-tool proposal  
+`proposed-stale-derived-and-include-pinning.md`.
 
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