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/runtime.sx

@@ -495,6 +495,47 @@
     (n)
     (set! cl-restart-stack (slice cl-restart-stack n (len cl-restart-stack)))))
 
+;; ── *debugger-hook* + invoke-debugger ────────────────────────────────────
+;;
+;; cl-debugger-hook: called when an error propagates with no handler.
+;; Signature: (fn (condition hook) result). The hook arg is itself
+;; (so the hook can rebind it to nil to prevent recursion).
+;; nil = use default (re-raise as host error).
+
+(define cl-debugger-hook nil)
+
+(define cl-invoke-debugger
+  (fn (c)
+    (if (nil? cl-debugger-hook)
+      (error (str "Debugger: " (cl-condition-message c)))
+      (let ((hook cl-debugger-hook))
+        (set! cl-debugger-hook nil)
+        (let ((result (hook c hook)))
+          (set! cl-debugger-hook hook)
+          result)))))
+
+;; ── *break-on-signals* ────────────────────────────────────────────────────
+;;
+;; When set to a type name string, cl-signal invokes the debugger hook
+;; before walking handlers if the condition is of that type.
+;; nil = disabled (ANSI default).
+
+(define cl-break-on-signals nil)
+
+;; ── invoke-restart-interactively ──────────────────────────────────────────
+;;
+;; Like invoke-restart but calls the restart's fn with no arguments
+;; (real CL would prompt the user for each arg via :interactive).
+
+(define cl-invoke-restart-interactively
+  (fn (name)
+    (let ((entry (cl-find-restart-entry name cl-restart-stack)))
+      (if (nil? entry)
+        (error (str "No active restart: " name))
+        (let ((restart-fn (get entry "fn"))
+              (escape     (get entry "escape")))
+          (escape (restart-fn)))))))
+
 ;; ── cl-signal (non-unwinding) ─────────────────────────────────────────────
 ;;
 ;; Walks cl-handler-stack; for each matching entry, calls the handler fn.
@@ -514,12 +555,16 @@
           (begin ((get entry "fn") obj) (cl-signal-obj obj (rest stack)))
           (cl-signal-obj obj (rest stack)))))))
 
-(define
-  cl-signal
-  (fn
-    (c)
-    (let
-      ((obj (if (cl-condition? c) c (cl-make-condition "simple-condition" "format-control" (str c)))))
+(define cl-signal
+  (fn (c)
+    (let ((obj (if (cl-condition? c)
+                 c
+                 (cl-make-condition "simple-condition"
+                   "format-control" (str c)))))
+      ;; *break-on-signals*: invoke debugger hook when type matches
+      (when (and (not (nil? cl-break-on-signals))
+                 (cl-condition-of-type? obj cl-break-on-signals))
+        (cl-invoke-debugger obj))
       (cl-signal-obj obj cl-handler-stack))))
 
 ;; ── cl-error ───────────────────────────────────────────────────────────────
@@ -533,7 +578,7 @@
     (let
       ((obj (cond ((cl-condition? c) c) ((string? c) (cl-make-condition "simple-error" "format-control" c "format-arguments" args)) (:else (cl-make-condition "simple-error" "format-control" (str c))))))
       (cl-signal-obj obj cl-handler-stack)
-      (error (str "Unhandled CL error: " (cl-condition-message obj))))))
+      (cl-invoke-debugger obj))))
 
 ;; ── cl-warn ────────────────────────────────────────────────────────────────
 
@@ -660,12 +705,20 @@
 ;; Signals a continuable error. The "continue" restart is established;
 ;; invoke-restart "continue" to proceed past the error.
 
-(define
-  cl-cerror
-  (fn
-    (continue-string c &rest args)
-    (let
-      ((obj (if (cl-condition? c) c (cl-make-condition "simple-error" "format-control" (str c) "format-arguments" args))))
+
+
+;; ── cl-cerror ──────────────────────────────────────────────────────────────
+;;
+;; Signals a continuable error. The "continue" restart is established;
+;; invoke-restart "continue" to proceed past the error.
+
+(define cl-cerror
+  (fn (continue-string c &rest args)
+    (let ((obj (if (cl-condition? c)
+                 c
+                 (cl-make-condition "simple-error"
+                   "format-control" (str c)
+                   "format-arguments" args))))
       (cl-restart-case
         (fn () (cl-signal-obj obj cl-handler-stack))
         (list "continue" (list) (fn () nil))))))

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 ────────────────────────────────────────────────────────────────
 
 (if

plans/common-lisp-on-sx.md

@@ -73,7 +73,7 @@ Core mapping:
 - [x] `restart-case`, `with-simple-restart`, `restart-bind`
 - [x] `find-restart`, `invoke-restart`, `compute-restarts`
 - [x] `with-condition-restarts` — associate restarts with a specific condition
-- [ ] `invoke-restart-interactively`, `*break-on-signals*`, `*debugger-hook*` (basic)
+- [x] `invoke-restart-interactively`, `*break-on-signals*`, `*debugger-hook*` (basic)
 - [x] Classic programs in `lib/common-lisp/tests/programs/`:
   - [x] `restart-demo.sx` — division with `use-zero` and `retry` restarts (7 tests)
   - [x] `parse-recover.sx` — parser with skipped-token restart (6 tests)
@@ -124,6 +124,7 @@ data; format for string templating.
 
 _Newest first._
 
+- 2026-05-05: Phase 3 complete — cl-debugger-hook/cl-invoke-debugger in runtime.sx (cl-error routes through hook), cl-break-on-signals (fires hook before handlers on type match), cl-invoke-restart-interactively (calls fn with no args); 4 new tests (147 total). Phase 3 all boxes ticked.
 - 2026-05-05: Phase 3 interactive-debugger.sx — cl-debugger-hook global, cl-invoke-debugger, cl-error-with-debugger, make-policy-debugger; 7 tests (143 total). Tests wired into test.sh program suite runner. Phase 3 condition core complete.
 - 2026-05-05: Phase 3 classic programs — `tests/programs/restart-demo.sx` (7 tests: safe-divide with use-zero + retry restarts) and `tests/programs/parse-recover.sx` (6 tests: token parser with skip-token + use-zero restarts, handler-case abort). Key gotcha: use `=` not `equal?` for list comparison in sx_server.
 - 2026-05-05: Phase 3 conditions + restarts — `cl-condition-classes` hierarchy (15 types), `cl-condition?`/`cl-condition-of-type?`, `cl-make-condition`, `cl-define-condition`, `cl-signal`/`cl-error`/`cl-warn`/`cl-cerror`, `cl-handler-bind` (non-unwinding), `cl-handler-case` (call/cc escape), `cl-restart-case`/`cl-with-simple-restart`, `cl-find-restart`/`cl-invoke-restart`/`cl-compute-restarts`, `cl-with-condition-restarts`; 55 new tests in `tests/conditions.sx` (123 total runtime tests). Key gotcha: `cl-condition-classes` must be captured at define-time via `let` in `cl-condition-of-type?` — free-variable lookup at call-time fails through env_merge parent chain.