content: ordered block document + edit ops + 40 tests

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

plans/content-on-sx.md

@@ -19,7 +19,7 @@ injected adapter, not core.
 
 ## Status (rolling)
 
-`bash lib/content/conformance.sh` → **38/38** (Phase 1: typed blocks)
+`bash lib/content/conformance.sh` → **78/78** (Phase 1: blocks + doc)
 
 ## Ground rules
 
@@ -58,7 +58,7 @@ lib/content/api.sx ── (content/edit) (content/render) (content/history) ─
 
 ## Phase 1 — Block document model
 - [x] `block.sx` — typed block objects
-- [ ] `doc.sx` — ordered tree, apply edit op, structural moves
+- [x] `doc.sx` — ordered tree, apply edit op, structural moves
 - [ ] `render.sx` — block tree → HTML/SX
 - [ ] `api.sx` + tests + scoreboard + conformance.sh
 
@@ -77,6 +77,12 @@ lib/content/api.sx ── (content/edit) (content/render) (content/history) ─
 
 ## Progress log
 
+- 2026-06-06 — Phase 1 `doc.sx`: ordered block document (`CtDoc`) as a
+  Smalltalk object holding an ordered block sequence. Edit ops are data dicts
+  (`insert`/`update`/`move`/`delete`) with `op-*` constructors; `doc-apply` /
+  `doc-apply-all` interpret an op stream, each returning a NEW document (input
+  never mutated → replay-safe). Structural moves, insert-after/at, find/index,
+  immutability all tested. 40 tests; suite 78/78.
 - 2026-06-06 — Phase 1 `block.sx`: typed block objects as Smalltalk instances
   (`CtBlock` hierarchy: text/heading/code/quote/image/embed/divider/list).
   Type tag + accessors are message sends (polymorphic dispatch); fields are