cl: Phase 3 complete — *debugger-hook*, *break-on-signals*, invoke-restart-interactively (147 tests)

cl-debugger-hook: mutable global (fn (c hook) result); cl-invoke-debugger
calls it with infinite-recursion guard (sets hook nil during call).
cl-error now routes unhandled errors through cl-invoke-debugger instead of
bare host error — allows the hook to invoke a restart and resume.
cl-break-on-signals: when set to a type name, cl-signal fires the debugger
hook before walking handlers if the condition matches.
cl-invoke-restart-interactively: calls the restart fn with no args (no
terminal protocol — equivalent to (invoke-restart name)).
4 new tests in conditions.sx covering all three; Phase 3 fully complete.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/common-lisp/tests/conditions.sx

@@ -401,6 +401,72 @@
       (cl-arithmetic-error-operands c)
       (list 1 0))))
 
+
+;; ── 15. *debugger-hook* ───────────────────────────────────────────────────
+
+(reset-stacks!)
+
+(let ((received nil))
+  (begin
+    (set! cl-debugger-hook
+      (fn (c h)
+        (set! received (cl-condition-message c))
+        (cl-invoke-restart "escape")))
+    (cl-restart-case
+      (fn () (cl-error "debugger test"))
+      (list "escape" (list) (fn () nil)))
+    (set! cl-debugger-hook nil)
+    (assert-equal "debugger-hook receives condition"  received  "debugger test")))
+
+(reset-stacks!)
+
+;; ── 16. *break-on-signals* ────────────────────────────────────────────────
+
+(reset-stacks!)
+
+(let ((triggered false))
+  (begin
+    (set! cl-break-on-signals "error")
+    (set! cl-debugger-hook
+      (fn (c h)
+        (set! triggered true)
+        (cl-invoke-restart "abort")))
+    (cl-restart-case
+      (fn ()
+        (cl-signal (cl-make-condition "simple-error" "format-control" "x")))
+      (list "abort" (list) (fn () nil)))
+    (set! cl-break-on-signals nil)
+    (set! cl-debugger-hook nil)
+    (assert-true "break-on-signals fires hook"  triggered)))
+
+(reset-stacks!)
+
+;; break-on-signals: non-matching type does NOT fire hook
+(let ((triggered false))
+  (begin
+    (set! cl-break-on-signals "error")
+    (set! cl-debugger-hook
+      (fn (c h) (set! triggered true) nil))
+    (cl-handler-bind
+      (list (list "warning" (fn (c) nil)))
+      (fn ()
+        (cl-signal (cl-make-condition "simple-warning" "format-control" "w"))))
+    (set! cl-break-on-signals nil)
+    (set! cl-debugger-hook nil)
+    (assert-equal "break-on-signals: type mismatch not triggered"  triggered  false)))
+
+(reset-stacks!)
+
+;; ── 17. cl-invoke-restart-interactively ──────────────────────────────────
+
+(let ((result
+        (cl-restart-case
+          (fn () (cl-invoke-restart-interactively "use-default"))
+          (list "use-default" (list) (fn () 99)))))
+  (assert-equal "invoke-restart-interactively: returns restart value"  result  99))
+
+(reset-stacks!)
+
 ;; ── summary ────────────────────────────────────────────────────────────────
 
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