Fix code-review findings: 10-known.sh value-match bug (proven live), bootstrap.sh symlink race + missing sources + accidental exit-on-eval, fx.sh misleading picker text + FX_AUTO short-circuit

contrib/fx/fx.sh

@@ -62,13 +62,27 @@ fx() {
     fi
     export FX_OUTPUT
 
+    # Under FX_AUTO only the first candidate is ever used (head -1
+    # below), so gathering every source unconditionally would mean
+    # always paying for the 25-30s local-LLM/remote-API tiers even
+    # when a free source already answered and that answer is
+    # guaranteed to win -- exactly the cost the NN- numbering claims to
+    # avoid. Stop at the first source that produces anything once
+    # FX_AUTO is set. Without it (the interactive picker), keep
+    # gathering everything: a later, better-verified candidate
+    # shouldn't be hidden behind an earlier weak match when a human is
+    # the one choosing.
     candidates=$(
         for src in "$FX_SOURCES_DIR"/*; do
             [ -x "$src" ] || continue
             label="${src##*/}"
-            "$src" "$cmd" 2>/dev/null | while IFS= read -r line; do
-                [ -n "$line" ] && printf '[%s] %s\n' "$label" "$line"
-            done
+            out=$("$src" "$cmd" 2>/dev/null)
+            if [ -n "$out" ]; then
+                printf '%s\n' "$out" | while IFS= read -r line; do
+                    [ -n "$line" ] && printf '[%s] %s\n' "$label" "$line"
+                done
+                [ -n "$FX_AUTO" ] && break
+            fi
         done | awk -F'] ' '!seen[$2]++'
     )
 
@@ -83,7 +97,12 @@ fx() {
             printf '%s\n' "$candidates" | while IFS= read -r line; do
                 i=$((i+1)); printf '%d) %s\n' "$i" "$line"
             done
-            printf 'pick a number (blank to type your own): '
+            # "blank to give up", not "type your own": fx already
+            # committed f's stdin to this pipe, so a blank answer here
+            # can't fall through to a real terminal read the way f()'s
+            # own bare prompt does -- it just pipes an empty line into
+            # f(), same as when zero candidates were found at all.
+            printf 'pick a number (blank to give up): '
             read -r n
             [ -n "$n" ] && chosen=$(printf '%s\n' "$candidates" | sed -n "${n}p" | sed 's/^\[[^]]*\] //')
         fi