artdag: job-as-post-object projection (post.sx) + 12 tests

lib/artdag/post.sx — the artdag-side projection for 'a job is a type of post' (per the
host loop). job->post-object: {:type artdag/job :id <output content-id> :wire <dag->wire>},
post-id = content-id = natural AP object id. post-object-verify binds the id to the payload
(record ids recompute + post id present), rejecting tampered params/bogus ids. String
transport for the feed/SXTP body; post-run lets a peer decode->run->result, content-address
cache-hitting. Activity wrapping stays host-side. post 12/12, total 225/225.

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

lib/artdag/conformance.sh

@@ -13,7 +13,7 @@ if [ ! -x "$SX_SERVER" ]; then
   exit 1
 fi
 
-SUITES=(dag analyze plan execute optimize fed cost serialize stats fault maude-optimize schedule)
+SUITES=(dag analyze plan execute optimize fed cost serialize stats fault post maude-optimize schedule)
 
 OUT_JSON="lib/artdag/scoreboard.json"
 OUT_MD="lib/artdag/scoreboard.md"
@@ -96,6 +96,7 @@ ${MK_LOADS}
 (load "lib/artdag/serialize.sx")
 (load "lib/artdag/stats.sx")
 (load "lib/artdag/fault.sx")
+(load "lib/artdag/post.sx")
 (load "lib/artdag/api.sx")
 ${BRIDGE_LOAD}
 ${SCHED_LOAD}

lib/artdag/post.sx

@@ -0,0 +1,68 @@
+; lib/artdag/post.sx — project an artdag job to/from a feed "post object", so a job
+; can ride as the :object of a feed activity ({:actor :verb :object :at :tags}) per the
+; host loop. A post object is content-addressed and self-verifying:
+;   {:type "artdag/job" :id <content-id of the output node> :wire <dag->wire>}
+; The :id IS the post/object id (the stable structural digest = natural AP object id);
+; the :wire is the self-describing, write/read-safe payload from serialize.sx whose
+; records each carry their own content-id. The dag<->feed-activity wrapping (actor/verb/
+; at/tags) stays on the host/feed side; this file is only the job<->object projection.
+; Depends on dag.sx + serialize.sx (and execute.sx for post-run).
+
+(define artdag/post-type "artdag/job")
+
+; a job = a dag + the output node (by author name) the post is "about".
+(define artdag/job->post-object (fn (dag output-name) {:id (artdag/dag-id dag output-name) :type artdag/post-type :wire (artdag/dag->wire dag)}))
+
+(define
+  artdag/post-object?
+  (fn
+    (x)
+    (and
+      (= (type-of x) "dict")
+      (= (get x :type) artdag/post-type)
+      (has-key? x :id)
+      (has-key? x :wire))))
+
+(define artdag/post-object-id (fn (post) (get post :id)))
+
+(define artdag/post-object-wire (fn (post) (get post :wire)))
+
+; integrity: the payload's records each verify (id == recomputed content-id) AND the
+; claimed post id is actually produced by the job (present among the wire records).
+(define
+  artdag/post-object-verify
+  (fn
+    (post)
+    (and
+      (artdag/post-object? post)
+      (artdag/wire-verify (get post :wire))
+      (artdag/member?
+        (get post :id)
+        (map (fn (rec) (nth rec 0)) (get post :wire))))))
+
+; decode the payload back into a runnable dag (pure; verify separately, mirroring
+; serialize.sx's wire->dag / wire-verify split).
+(define
+  artdag/post-object->job
+  (fn (post) (artdag/wire->dag (get post :wire))))
+
+; ---- string transport (drop into a feed activity / SXTP body) ----
+
+(define
+  artdag/job->post-string
+  (fn
+    (dag output-name)
+    (write-to-string (artdag/job->post-object dag output-name))))
+
+(define artdag/post-string->object (fn (s) (read (open-input-string s))))
+
+; ---- run a received post: decode -> run -> result at the post id ----
+; the peer recomputes the job (content-addressed, so a warm cache hits everything it
+; already has). Returns the result of the output node the post is about.
+(define
+  artdag/post-run
+  (fn
+    (post runner cache)
+    (artdag/result-of
+      (artdag/run (artdag/post-object->job post) runner cache)
+      (artdag/post-object-id post))))

lib/artdag/scoreboard.json

@@ -10,10 +10,11 @@
     "serialize": {"pass": 13, "fail": 0},
     "stats": {"pass": 12, "fail": 0},
     "fault": {"pass": 14, "fail": 0},
+    "post": {"pass": 12, "fail": 0},
     "maude-optimize": {"pass": 40, "fail": 0},
     "schedule": {"pass": 15, "fail": 0}
   },
-  "total_pass": 213,
+  "total_pass": 225,
   "total_fail": 0,
-  "total": 213
+  "total": 225
 }

lib/artdag/scoreboard.md

@@ -14,6 +14,7 @@ _Generated by `lib/artdag/conformance.sh`_
 | serialize | 13 | 0 | 13 |
 | stats | 12 | 0 | 12 |
 | fault | 14 | 0 | 14 |
+| post | 12 | 0 | 12 |
 | maude-optimize | 40 | 0 | 40 |
 | schedule | 15 | 0 | 15 |
-| **Total** | **213** | **0** | **213** |
+| **Total** | **225** | **0** | **225** |

lib/artdag/tests/post.sx

@@ -0,0 +1,111 @@
+; Forward direction — artdag job as a feed "post object" (per the host loop).
+; A job projects to a content-addressed, self-verifying object suitable as a feed
+; activity :object; a peer decodes, verifies and runs it to the same result.
+
+(define po-runner (artdag/op-table-runner {:blur (fn (params inputs) (+ (first inputs) (get params :radius))) :src (fn (params inputs) 0) :over (fn (params inputs) (+ (nth inputs 0) (nth inputs 1)))}))
+
+(define
+  po-job
+  (artdag/build
+    (list
+      (list "s" "src" (list) {})
+      (list "b" "blur" (list "s") {:radius 2})
+      (list "c" "blur" (list "s") {:radius 3})
+      (list "out" "over" (list "b" "c") {} true))))
+(define po-out-id (artdag/dag-id po-job "out"))
+(define po-post (artdag/job->post-object po-job "out"))
+
+(artdag-test
+  "post: is a well-formed post object"
+  (artdag/post-object? po-post)
+  true)
+
+(artdag-test "post: type tag is artdag/job" (get po-post :type) "artdag/job")
+
+(artdag-test
+  "post: post id is the output node's content-id"
+  (artdag/post-object-id po-post)
+  po-out-id)
+
+(artdag-test
+  "post: payload is the whole dag (one record per node)"
+  (len (artdag/post-object-wire po-post))
+  (artdag/node-count po-job))
+
+(artdag-test
+  "post: verifies (ids intact, output present)"
+  (artdag/post-object-verify po-post)
+  true)
+
+; ---- round-trip: decode reconstructs the job by content-id ----
+
+(define po-job2 (artdag/post-object->job po-post))
+
+(artdag-test
+  "post: decoded job contains the output node by content-id"
+  (artdag/member? po-out-id (keys (artdag/dag-nodes po-job2)))
+  true)
+
+(artdag-test
+  "post: decoded job has the same node count"
+  (artdag/node-count po-job2)
+  (artdag/node-count po-job))
+
+; ---- string transport (feed activity / SXTP body) ----
+
+(define po-str (artdag/job->post-string po-job "out"))
+(define po-post2 (artdag/post-string->object po-str))
+
+(artdag-test
+  "post: survives string transport (id preserved)"
+  (artdag/post-object-id po-post2)
+  po-out-id)
+
+(artdag-test
+  "post: transported post still verifies"
+  (artdag/post-object-verify po-post2)
+  true)
+
+; ---- a peer runs the received post to the same result ----
+
+(define
+  po-local-result
+  (artdag/result-of (artdag/run po-job po-runner (persist/open)) po-out-id))
+(define po-peer-result (artdag/post-run po-post2 po-runner (persist/open)))
+
+(artdag-test
+  "post: peer runs the received job to the same result"
+  (= po-peer-result po-local-result)
+  true)
+
+; ---- tamper detection: mutate a param under a stale id ----
+
+(define
+  po-tampered
+  (assoc
+    po-post
+    :wire (map
+      (fn
+        (rec)
+        (if
+          (= (nth rec 1) "blur")
+          (list
+            (nth rec 0)
+            (nth rec 1)
+            (nth rec 2)
+            {:radius 99}
+            (nth rec 4))
+          rec))
+      (artdag/post-object-wire po-post))))
+
+(artdag-test
+  "post: tampered payload fails verification"
+  (artdag/post-object-verify po-tampered)
+  false)
+
+; ---- an id not produced by the job fails verification ----
+
+(artdag-test
+  "post: post id absent from payload fails verification"
+  (artdag/post-object-verify (assoc po-post :id "node:bogus"))
+  false)