docs(framework): P4.1 — fix stale install.sh comments + cmp-equal early-exit

Non-blocking fast-follow from #590 dual-engine review:
- install.sh: PRESERVE_PATHS "(never overwritten)" and the seed-block "never be
  overwritten once customized" comments contradicted P4's framework-owned
  overwrite — clarified both (PRESERVE protects from rsync --delete; reconcile
  re-applies framework-owned with backup-once).
- reconcile (install.sh + file-adapter.ts): skip the copy when content already
  matches (cmp-equal early-exit) to avoid mtime churn. Parity preserved.

install.sh fixtures 14/14 green; gate green; prettier clean.

Refs #542, closes #592

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/mosaic/framework/install.sh

@@ -19,7 +19,9 @@ SOURCE_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 TARGET_DIR="${MOSAIC_HOME:-$HOME/.config/mosaic}"
 INSTALL_MODE="${MOSAIC_INSTALL_MODE:-prompt}"
 
-# Files/dirs preserved across upgrades (never overwritten).
+# Files/dirs protected from rsync --delete during sync. NOTE: framework-owned
+# entries (CONSTITUTION/AGENTS/STANDARDS) ARE re-applied afterward by
+# reconcile_framework_files (overwrite + backup-once); the rest stay user-owned.
 # User-created content in these paths survives rsync --delete.
 PRESERVE_PATHS=("CONSTITUTION.md" "AGENTS.md" "SOUL.md" "USER.md" "TOOLS.md" "STANDARDS.md" "memory" "sources" "credentials")
 
@@ -70,12 +72,14 @@ reconcile_framework_files() {
   [[ -d "$defaults" ]] || return 0
   for f in "${FRAMEWORK_OWNED[@]}"; do
     [[ -f "$defaults/$f" ]] || continue
-    if [[ -f "$TARGET_DIR/$f" ]] && ! cmp -s "$TARGET_DIR/$f" "$defaults/$f"; then
+    # Already current — skip to avoid mtime churn.
-      if [[ ! -f "$TARGET_DIR/${f}.pre-constitution.bak" ]]; then
+    if [[ -f "$TARGET_DIR/$f" ]] && cmp -s "$TARGET_DIR/$f" "$defaults/$f"; then
+      continue
+    fi
+    if [[ -f "$TARGET_DIR/$f" && ! -f "$TARGET_DIR/${f}.pre-constitution.bak" ]]; then
       cp "$TARGET_DIR/$f" "$TARGET_DIR/${f}.pre-constitution.bak"
       warn "$f is now framework-owned and was updated; your previous copy is saved as ${f}.pre-constitution.bak — re-apply intended changes as a .local overlay or policy/ file (see CONSTITUTION.md / constitution/LAYER-MODEL.md)."
     fi
-    fi
     cp "$defaults/$f" "$TARGET_DIR/$f"
   done
   for f in "${USER_SEEDED[@]}"; do
@@ -281,9 +285,9 @@ sync_framework
 mkdir -p "$TARGET_DIR/memory"
 mkdir -p "$TARGET_DIR/credentials"
 
-# Seed defaults — copy framework contract files from defaults/ to framework
+# Reconcile contract files from defaults/ into the framework root: framework-owned
-# root if not already present. These ship with sensible defaults but must
+# files (CONSTITUTION/AGENTS/STANDARDS) are overwritten every upgrade (a divergent
-# never be overwritten once the user has customized them.
+# copy is backed up once); user-seeded files (TOOLS) are written on first install only.
 #
 # This list must match the framework-contract whitelist in
 # packages/mosaic/src/config/file-adapter.ts (FileConfigAdapter.syncFramework).

packages/mosaic/src/config/file-adapter.ts

@@ -198,8 +198,10 @@ export class FileConfigAdapter implements ConfigService {
         const src = join(defaultsDir, entry);
         const dest = join(this.mosaicHome, entry);
         if (!existsSync(src) || !statSync(src).isFile()) continue;
+        // Already current — skip to avoid mtime churn.
+        if (existsSync(dest) && readFileSync(src).equals(readFileSync(dest))) continue;
         const bak = `${dest}.pre-constitution.bak`;
-        if (existsSync(dest) && !readFileSync(src).equals(readFileSync(dest)) && !existsSync(bak)) {
+        if (existsSync(dest) && !existsSync(bak)) {
           copyFileSync(dest, bak);
         }
         copyFileSync(src, dest);