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+# Implement plan 19: scoped literal rich-text whitespace
+
+Read approved plan 19 from local planning checkout only when HEAD equals
+`a2557b2ad40e06e1e63eb655f286e6a78fe6bf0d`; otherwise use
+`git show a2557b2ad40e06e1e63eb655f286e6a78fe6bf0d:plans/19-literal-rich-text-whitespace.md`. Read current `AGENTS.md`,
+RTK, issue/domain guidance, ADRs, applicable TDD skills, and completed Plan 16 implementation/review reports. This unit must
+start from or rebase onto reviewed Plan 16 head because both own rich editor/HTML seams; never implement concurrently. Run
+root Intent inventory and load matching local skill before edits. Do not spawn subagents, touch ledger, mutate issues, merge,
+push, or create PR.
+
+Require clean dependent worktree, revalidate issue 3397/open PRs/current main and Plan 16 head, rename branch
+`codex/issue-3397-literal-whitespace`, and record exact stacked base. Preserve paragraph indentation, Unicode-space fixes, and
+table-cell support. Approved persisted marker is `data-resume-whitespace="preserve"`; unmarked legacy HTML must remain
+unchanged. No global whitespace mode, NBSP substitution, code-block feature, or tab-key redesign.
+
+Strict TDD, atomic web/PDF/DOCX contract:
+
+- Record current GREEN characterization. Add failing marked paragraph/heading tests while existing unmarked ASCII collapse,
+  pretty-printed import, Unicode spaces, indentation, lists, quotes, Enter/Shift+Enter, and table regressions remain green.
+- Newly authored blocks and blocks receiving text-input/paste mark preservation; mount, prop update, and unmarked legacy import
+  do not mark or emit saves. Exact leading/interior/trailing spaces and tab codepoints survive save/remount, undo/redo,
+  paragraph↔heading, list transitions without data loss, marks, line breaks, RTL, and supported Plan 16 table cells.
+- Scope editor display behavior to marked nodes. Preserve unsupported-content channel from Plan 16.
+- PDF preserves only marked node-local whitespace. One tab adds exactly four ordinary-space advances; two add eight,
+  independent of current x. Spaces remain breakable; narrow content never disappears. Do not disable dependency collapse
+  globally; patch CJS/ESM and frozen install only if no smaller neutral adapter exists.
+- DOCX emits preserved-space representation and the same logical four-space tab contract; verify XML plus rendered geometry
+  when claiming visual width.
+- Add synthetic authenticated E2E: type/paste, save/reload, JSON/PDF/DOCX export, exact codepoints and output geometry. No
+  private content.
+
+Run focused web/PDF/DOCX tests including Plan 16 table regressions, affected typechecks, boundaries, full build, E2E against
+dedicated DB, narrow non-writing Biome, and diff/scope gates. Disclose/inspect any write-capable `pnpm check`. Commit locally;
+no push/PR before independent review.
+
+Write `.orchestration/plan-19-implementation.md`: exact dependency/base, live/drift state, facts vs uncertainty, RED/GREEN,
+commit/files, tests/results, skipped visual/E2E gates, risks, issue coverage, PR `not created`. Final response at most ten lines.