From 20f06e2eb9284c8ca77b789bb22d6e16e7efe318 Mon Sep 17 00:00:00 2001
From: Puck Meerburg <puck@puckipedia.com>
Date: Sun, 9 Mar 2025 09:47:26 +0000
Subject: [PATCH] (zilch planner step): track historical build plan steps

---
 planner/src/step.sld | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/planner/src/step.sld b/planner/src/step.sld
index d53d6f4..6a95f23 100644
--- a/planner/src/step.sld
+++ b/planner/src/step.sld
@@ -23,13 +23,17 @@
     (finalized build-plan-finalized set-build-plan-finalized!)
     (last-id build-plan-last-id set-build-plan-last-id!))
 
+  ;; Represents a single step in the build.
+  ;; id is a monotonically increasing identifier.
+  ;; dependencies is an alist of identifiers for other build steps to when they were added.
   (define-record-type <build-step>
-    (make-build-step id dependencies type arguments)
+    (make-build-step id dependencies type arguments called-from)
     build-step?
     (id build-step-id)
     (dependencies build-step-dependencies set-build-step-dependencies!)
     (type build-step-type)
-    (arguments build-step-arguments set-build-step-arguments!))
+    (arguments build-step-arguments set-build-step-arguments!)
+    (called-from build-step-called-from))
 
   (define-record-type <build-step-type>
     (make-build-step-type proc name batch)
@@ -51,7 +55,7 @@
   ;; Appends a new step to the build plan, returning its ID.
   (define (build-plan-append plan type args dependencies)
     (define id (build-plan-next-id plan))
-    (define new-step (make-build-step id dependencies type args))
+    (define new-step (make-build-step id dependencies type args #f))
     (set-build-plan-steps! plan (mapping-set! (build-plan-steps plan) id new-step))
     id)
 
@@ -154,10 +158,17 @@
           (make-build-step (build-step-id step)
            (list-ref result 3)
            (list-ref result 1)
-           (list-ref result 2)))))
+           (list-ref result 2)
+           (cons (build-plan-next-id plan) step)))))
        ((append)
-        (set-build-step-dependencies! step (append (build-step-dependencies step) (list-ref result 1)))
-        (unless (eq? (list-ref result 2) #f) (set-build-step-arguments! step (list-ref result 2))))))
+        (set-build-plan-steps! plan
+         (mapping-set! (build-plan-steps plan)
+          (build-step-id step)
+          (make-build-step (build-step-id step)
+           (append (build-step-dependencies step) (list-ref result 1))
+           (build-step-type step)
+           (or (list-ref result 2) (build-step-arguments step))
+           (cons (build-plan-next-id plan) step)))))))
 
     ;; Run all build steps that are ready to run.
     (mapping-for-each