diff --git a/lib/git/conformance.sh b/lib/git/conformance.sh
new file mode 100755
index 00000000..62057e19
--- /dev/null
+++ b/lib/git/conformance.sh
@@ -0,0 +1,115 @@
+#!/usr/bin/env bash
+# lib/git/conformance.sh — run sx-git test suites, emit scoreboard.json + scoreboard.md.
+
+set -uo pipefail
+cd "$(git rev-parse --show-toplevel)"
+
+SX_SERVER="${SX_SERVER:-hosts/ocaml/_build/default/bin/sx_server.exe}"
+if [ ! -x "$SX_SERVER" ]; then
+  SX_SERVER="/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe"
+fi
+if [ ! -x "$SX_SERVER" ]; then
+  echo "ERROR: sx_server.exe not found." >&2
+  exit 1
+fi
+
+SUITES=(object)
+
+OUT_JSON="lib/git/scoreboard.json"
+OUT_MD="lib/git/scoreboard.md"
+
+run_suite() {
+  local suite=$1
+  local file="lib/git/tests/${suite}.sx"
+  local TMP
+  TMP=$(mktemp)
+  cat > "$TMP" << EPOCHS
+(epoch 1)
+(load "spec/stdlib.sx")
+(load "lib/r7rs.sx")
+(load "lib/persist/event.sx")
+(load "lib/persist/backend.sx")
+(load "lib/persist/log.sx")
+(load "lib/persist/kv.sx")
+(load "lib/artdag/dag.sx")
+(load "lib/git/object.sx")
+(epoch 2)
+(eval "(define git-test-pass 0)")
+(eval "(define git-test-fail 0)")
+(eval "(define git-test-failures (list))")
+(eval "(define git-test (fn (name got expected) (if (equal? got expected) (set! git-test-pass (+ git-test-pass 1)) (begin (set! git-test-fail (+ git-test-fail 1)) (set! git-test-failures (append git-test-failures (list (list name (inspect got) (inspect expected)))))))))")
+(epoch 3)
+(load "${file}")
+(epoch 4)
+(eval "(list git-test-pass git-test-fail)")
+EPOCHS
+
+  local OUTPUT
+  OUTPUT=$(timeout 300 "$SX_SERVER" < "$TMP" 2>/dev/null)
+  rm -f "$TMP"
+
+  local LINE
+  LINE=$(echo "$OUTPUT" | awk '/^\(ok-len 4 / {getline; print; exit}')
+  if [ -z "$LINE" ]; then
+    LINE=$(echo "$OUTPUT" | grep -E '^\(ok 4 \([0-9]+ [0-9]+\)\)' | tail -1 \
+            | sed -E 's/^\(ok 4 //; s/\)$//')
+  fi
+
+  local P F
+  P=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\1/')
+  F=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\2/')
+  P=${P:-0}
+  F=${F:-0}
+  echo "${P} ${F}"
+}
+
+declare -A SUITE_PASS
+declare -A SUITE_FAIL
+TOTAL_PASS=0
+TOTAL_FAIL=0
+
+echo "Running sx-git conformance suite..." >&2
+for s in "${SUITES[@]}"; do
+  read -r p f < <(run_suite "$s")
+  SUITE_PASS[$s]=$p
+  SUITE_FAIL[$s]=$f
+  TOTAL_PASS=$((TOTAL_PASS + p))
+  TOTAL_FAIL=$((TOTAL_FAIL + f))
+  printf "  %-12s %d/%d\n" "$s" "$p" "$((p+f))" >&2
+done
+
+# scoreboard.json
+{
+  printf '{\n'
+  printf '  "suites": {\n'
+  first=1
+  for s in "${SUITES[@]}"; do
+    if [ $first -eq 0 ]; then printf ',\n'; fi
+    printf '    "%s": {"pass": %d, "fail": %d}' "$s" "${SUITE_PASS[$s]}" "${SUITE_FAIL[$s]}"
+    first=0
+  done
+  printf '\n  },\n'
+  printf '  "total_pass": %d,\n' "$TOTAL_PASS"
+  printf '  "total_fail": %d,\n' "$TOTAL_FAIL"
+  printf '  "total": %d\n' "$((TOTAL_PASS + TOTAL_FAIL))"
+  printf '}\n'
+} > "$OUT_JSON"
+
+# scoreboard.md
+{
+  printf '# sx-git Conformance Scoreboard\n\n'
+  printf '_Generated by `lib/git/conformance.sh`_\n\n'
+  printf '| Suite | Pass | Fail | Total |\n'
+  printf '|-------|-----:|-----:|------:|\n'
+  for s in "${SUITES[@]}"; do
+    p=${SUITE_PASS[$s]}
+    f=${SUITE_FAIL[$s]}
+    printf '| %s | %d | %d | %d |\n' "$s" "$p" "$f" "$((p+f))"
+  done
+  printf '| **Total** | **%d** | **%d** | **%d** |\n' "$TOTAL_PASS" "$TOTAL_FAIL" "$((TOTAL_PASS + TOTAL_FAIL))"
+} > "$OUT_MD"
+
+echo "Wrote $OUT_JSON and $OUT_MD" >&2
+echo "Total: $TOTAL_PASS pass, $TOTAL_FAIL fail" >&2
+
+[ "$TOTAL_FAIL" -eq 0 ]
diff --git a/lib/git/object.sx b/lib/git/object.sx
new file mode 100644
index 00000000..7822fee3
--- /dev/null
+++ b/lib/git/object.sx
@@ -0,0 +1,81 @@
+; lib/git/object.sx — sx-git Phase 1: blob/tree/commit/tag as content-addressed
+; TYPED objects over the persist kv store. Identity = host digest of the
+; canonical serialization (artdag/canon: sorted dict keys, escaped strings) —
+; native CIDs, NOT git wire bytes. Objects are plain dicts: typed, extensible;
+; unknown fields round-trip and participate in the CID.
+; Requires: lib/persist/backend.sx, lib/persist/kv.sx, lib/artdag/dag.sx.
+
+; ---- canonical form + content id ----
+(define git/canon (fn (obj) (artdag/canon obj)))
+
+(define
+  git/cid
+  (fn (obj) (str "sx1:" (crypto-sha256 (artdag/canon obj)))))
+
+; ---- repo handle: a persist backend + key prefix (many repos per db) ----
+(define git/repo-named (fn (db name) {:prefix name :db db}))
+(define git/repo (fn (db) (git/repo-named db "git")))
+(define git/repo-db (fn (repo) (get repo :db)))
+(define git/obj-key (fn (repo cid) (str (get repo :prefix) "/obj/" cid)))
+
+; ---- constructors ----
+(define git/blob (fn (data) {:data data :type "blob"}))
+
+; entries: dict of name -> entry, entry = {:kind "blob"|"tree" :cid cid ...}
+(define git/tree (fn (entries) {:type "tree" :entries entries}))
+(define git/tree-entry (fn (kind cid) {:kind kind :cid cid}))
+
+; meta: open dict (:author :message :time ... anything); protected keys win
+(define git/commit (fn (tree parents meta) (merge meta {:type "commit" :tree tree :parents parents})))
+
+(define git/tag (fn (target name meta) (merge meta {:name name :type "tag" :target target})))
+
+; ---- predicates / accessors ----
+(define git/object-type (fn (obj) (get obj :type)))
+(define
+  git/blob?
+  (fn (obj) (and (dict? obj) (equal? (get obj :type) "blob"))))
+(define
+  git/tree?
+  (fn (obj) (and (dict? obj) (equal? (get obj :type) "tree"))))
+(define
+  git/commit?
+  (fn (obj) (and (dict? obj) (equal? (get obj :type) "commit"))))
+(define
+  git/tag?
+  (fn (obj) (and (dict? obj) (equal? (get obj :type) "tag"))))
+
+(define git/blob-data (fn (obj) (get obj :data)))
+(define git/tree-entries (fn (obj) (get obj :entries)))
+(define git/tree-entry-for (fn (obj name) (get (get obj :entries) name)))
+(define
+  git/tree-names
+  (fn (obj) (artdag/sort-strings (keys (get obj :entries)))))
+(define git/entry-cid (fn (entry) (get entry :cid)))
+(define git/entry-kind (fn (entry) (get entry :kind)))
+(define git/commit-tree (fn (obj) (get obj :tree)))
+(define git/commit-parents (fn (obj) (get obj :parents)))
+(define git/commit-author (fn (obj) (get obj :author)))
+(define git/commit-message (fn (obj) (get obj :message)))
+(define git/tag-target (fn (obj) (get obj :target)))
+(define git/tag-name (fn (obj) (get obj :name)))
+
+; ---- object store: write/read/has, keyed by cid ----
+(define
+  git/write
+  (fn
+    (repo obj)
+    (let
+      ((cid (git/cid obj)))
+      (begin (persist/kv-put (get repo :db) (git/obj-key repo cid) obj) cid))))
+
+(define
+  git/read
+  (fn (repo cid) (persist/kv-get (get repo :db) (git/obj-key repo cid))))
+
+(define
+  git/has?
+  (fn (repo cid) (persist/kv-has? (get repo :db) (git/obj-key repo cid))))
+
+; convenience: write a blob straight from data
+(define git/write-blob (fn (repo data) (git/write repo (git/blob data))))
diff --git a/lib/git/scoreboard.json b/lib/git/scoreboard.json
new file mode 100644
index 00000000..85266dc8
--- /dev/null
+++ b/lib/git/scoreboard.json
@@ -0,0 +1,8 @@
+{
+  "suites": {
+    "object": {"pass": 38, "fail": 0}
+  },
+  "total_pass": 38,
+  "total_fail": 0,
+  "total": 38
+}
diff --git a/lib/git/scoreboard.md b/lib/git/scoreboard.md
new file mode 100644
index 00000000..a5896131
--- /dev/null
+++ b/lib/git/scoreboard.md
@@ -0,0 +1,8 @@
+# sx-git Conformance Scoreboard
+
+_Generated by `lib/git/conformance.sh`_
+
+| Suite | Pass | Fail | Total |
+|-------|-----:|-----:|------:|
+| object | 38 | 0 | 38 |
+| **Total** | **38** | **0** | **38** |
diff --git a/lib/git/tests/object.sx b/lib/git/tests/object.sx
new file mode 100644
index 00000000..1ba9bc9d
--- /dev/null
+++ b/lib/git/tests/object.sx
@@ -0,0 +1,241 @@
+; Phase 1 — object: blob/tree/commit/tag as content-addressed typed objects.
+; Fixture repo: blobs a/b/c, nested tree (a.txt b.txt sub/c.txt), two commits
+; (c2 modifies a.txt, parent c1), tag v1 -> c1. Reused as the assertion target.
+
+(define git-fix-db (persist/mem-backend))
+(define git-fix (git/repo git-fix-db))
+
+(define git-fix-blob-a (git/write-blob git-fix "hello\n"))
+(define git-fix-blob-b (git/write-blob git-fix "world\n"))
+(define git-fix-blob-c (git/write-blob git-fix "sub\n"))
+(define git-fix-blob-a2 (git/write-blob git-fix "hello2\n"))
+
+(define
+  git-fixt-entries3
+  (fn
+    (acid bcid subcid)
+    (assoc
+      (assoc
+        (assoc {} "a.txt" (git/tree-entry "blob" acid))
+        "b.txt"
+        (git/tree-entry "blob" bcid))
+      "sub"
+      (git/tree-entry "tree" subcid))))
+
+(define
+  git-fix-subtree-cid
+  (git/write
+    git-fix
+    (git/tree
+      (assoc {} "c.txt" (git/tree-entry "blob" git-fix-blob-c)))))
+
+(define
+  git-fix-tree1-cid
+  (git/write
+    git-fix
+    (git/tree
+      (git-fixt-entries3 git-fix-blob-a git-fix-blob-b git-fix-subtree-cid))))
+
+(define
+  git-fix-tree2-cid
+  (git/write
+    git-fix
+    (git/tree
+      (git-fixt-entries3 git-fix-blob-a2 git-fix-blob-b git-fix-subtree-cid))))
+
+(define
+  git-fix-commit1-cid
+  (git/write git-fix (git/commit git-fix-tree1-cid (list) {:message "c1" :time 1 :author "ada"})))
+
+(define
+  git-fix-commit2-cid
+  (git/write
+    git-fix
+    (git/commit git-fix-tree2-cid (list git-fix-commit1-cid) {:message "c2" :time 2 :author "ada"})))
+
+(define
+  git-fix-tag-cid
+  (git/write git-fix (git/tag git-fix-commit1-cid "v1" {:message "first" :tagger "ada"})))
+
+; ---- constructors + types ----
+(git-test "blob is typed" (git/object-type (git/blob "x")) "blob")
+(git-test "blob? true on blob" (git/blob? (git/blob "x")) true)
+(git-test
+  "blob? false on commit"
+  (git/blob? (git/commit "t" (list) {}))
+  false)
+(git-test "tree? true on tree" (git/tree? (git/tree {})) true)
+(git-test
+  "commit? true on commit"
+  (git/commit? (git/commit "t" (list) {}))
+  true)
+(git-test "tag? true on tag" (git/tag? (git/tag "c" "v" {})) true)
+(git-test "blob-data reads back" (git/blob-data (git/blob "hi")) "hi")
+
+; ---- cid: deterministic structural identity ----
+(git-test
+  "cid deterministic"
+  (equal? (git/cid (git/blob "same")) (git/cid (git/blob "same")))
+  true)
+(git-test
+  "cid differs by content"
+  (equal? (git/cid (git/blob "a")) (git/cid (git/blob "b")))
+  false)
+(git-test
+  "cid ignores dict insertion order"
+  (equal?
+    (git/cid (assoc (assoc {} :type "blob") :data "x"))
+    (git/cid (assoc (assoc {} :data "x") :type "blob")))
+  true)
+(git-test
+  "cid carries the native scheme prefix"
+  (starts-with? (git/cid (git/blob "x")) "sx1:")
+  true)
+
+; ---- write / read / has ----
+(git-test
+  "write returns the object cid"
+  (equal? git-fix-blob-a (git/cid (git/blob "hello\n")))
+  true)
+(git-test
+  "read round-trips blob data"
+  (git/blob-data (git/read git-fix git-fix-blob-a))
+  "hello\n")
+(git-test
+  "read round-trips structurally"
+  (equal? (git/read git-fix git-fix-blob-a) (git/blob "hello\n"))
+  true)
+(git-test "has? true after write" (git/has? git-fix git-fix-blob-a) true)
+(git-test "has? false for unknown cid" (git/has? git-fix "sx1:nope") false)
+(git-test "read unknown cid gives nil" (git/read git-fix "sx1:nope") nil)
+(git-test
+  "rewrite is idempotent, same cid"
+  (equal? (git/write git-fix (git/blob "hello\n")) git-fix-blob-a)
+  true)
+
+; ---- structural identity across separately built objects ----
+(git-test
+  "separately built identical tree shares the cid"
+  (equal?
+    (git/write
+      git-fix
+      (git/tree
+        (git-fixt-entries3 git-fix-blob-a git-fix-blob-b git-fix-subtree-cid)))
+    git-fix-tree1-cid)
+  true)
+(git-test
+  "changed entry changes the tree cid"
+  (equal? git-fix-tree1-cid git-fix-tree2-cid)
+  false)
+
+; ---- tree accessors ----
+(git-test
+  "tree entry lookup by name"
+  (git/entry-cid
+    (git/tree-entry-for (git/read git-fix git-fix-tree1-cid) "a.txt"))
+  git-fix-blob-a)
+(git-test
+  "tree entry kind"
+  (git/entry-kind
+    (git/tree-entry-for (git/read git-fix git-fix-tree1-cid) "sub"))
+  "tree")
+(git-test
+  "tree-names sorted"
+  (=
+    (git/tree-names (git/read git-fix git-fix-tree1-cid))
+    (list "a.txt" "b.txt" "sub"))
+  true)
+
+; ---- commit accessors ----
+(git-test
+  "commit tree cid"
+  (git/commit-tree (git/read git-fix git-fix-commit1-cid))
+  git-fix-tree1-cid)
+(git-test
+  "root commit has no parents"
+  (git/commit-parents (git/read git-fix git-fix-commit1-cid))
+  (list))
+(git-test
+  "child commit records its parent"
+  (git/commit-parents (git/read git-fix git-fix-commit2-cid))
+  (list git-fix-commit1-cid))
+(git-test
+  "commit author round-trips"
+  (git/commit-author (git/read git-fix git-fix-commit1-cid))
+  "ada")
+(git-test
+  "commit message round-trips"
+  (git/commit-message (git/read git-fix git-fix-commit2-cid))
+  "c2")
+(git-test
+  "commit cids differ across history"
+  (equal? git-fix-commit1-cid git-fix-commit2-cid)
+  false)
+
+; ---- typed extensibility (the reason for native CID) ----
+(git-test
+  "extra commit field round-trips"
+  (get
+    (git/read
+      git-fix
+      (git/write git-fix (git/commit "t" (list) {:message "m" :co-authored-by "claude"})))
+    :co-authored-by)
+  "claude")
+(git-test
+  "extra field changes the cid"
+  (equal?
+    (git/cid (git/commit "t" (list) {:m 1}))
+    (git/cid (git/commit "t" (list) {})))
+  false)
+(git-test
+  "protected keys win over meta"
+  (git/commit-tree (git/commit "t" (list) {:tree "evil"}))
+  "t")
+
+; ---- tag ----
+(git-test
+  "tag target"
+  (git/tag-target (git/read git-fix git-fix-tag-cid))
+  git-fix-commit1-cid)
+(git-test "tag name" (git/tag-name (git/read git-fix git-fix-tag-cid)) "v1")
+(git-test
+  "tag? on read-back"
+  (git/tag? (git/read git-fix git-fix-tag-cid))
+  true)
+
+; ---- full walk: commit -> tree -> subtree -> blob ----
+(git-test
+  "walk commit to nested blob"
+  (git/blob-data
+    (git/read
+      git-fix
+      (git/entry-cid
+        (git/tree-entry-for
+          (git/read
+            git-fix
+            (git/entry-cid
+              (git/tree-entry-for
+                (git/read
+                  git-fix
+                  (git/commit-tree (git/read git-fix git-fix-commit1-cid)))
+                "sub")))
+          "c.txt"))))
+  "sub\n")
+
+; ---- repos are namespaced within one backend ----
+(git-test
+  "objects are invisible across repo namespaces"
+  (let
+    ((db (persist/mem-backend)))
+    (let
+      ((ra (git/repo-named db "a")) (rb (git/repo-named db "b")))
+      (let ((cid (git/write-blob ra "x"))) (git/has? rb cid))))
+  false)
+(git-test
+  "same content, same cid in any repo"
+  (let
+    ((db (persist/mem-backend)))
+    (equal?
+      (git/write-blob (git/repo-named db "a") "x")
+      (git/write-blob (git/repo-named db "b") "x")))
+  true)