Clean page count: writer prompt constraint + single pre-delivery enforcement

Writer prompt (soft constraint):
- Added 90% fill rule: last page must be ≥90% filled
- Single-column: 10% whitespace at bottom of last page max
- Double-column: right column on last body page ≥90% filled
- Added expansion strategies (deepen analysis, more related work, etc.)

Hard enforcement (single checkpoint):
- Only at pre-delivery (before sending PDF to Telegram)
- Removed dev-phase and post-validate enforce calls
- _enforce_page_count now detects column layout from venue geometry:
  double-column → min = N - 0.05, single-column → min = N - 0.1
- Programmatic \clearpage injection before \bibliography

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: JihaoXin

ark/execution.py

@@ -628,11 +628,24 @@ def _enforce_page_count(self, context: str = "post-writing") -> bool:
         # First: ensure \clearpage before \bibliography (programmatic, no agent needed)
         self._ensure_clearpage_before_bibliography()
 
-        min_pages = venue_pages - 1 + 0.9  # e.g., 6 pages → 5.9 minimum
-        max_pages = venue_pages + 0.1      # e.g., 6 pages → 6.1 maximum
+        # 90% fill rule:
+        # Single-column: last page 90% filled → min = N - 0.1 (e.g., 6 → 5.9)
+        # Double-column: right column on last page 90% filled → min = N - 0.05 (stricter,
+        #   because half a page = one column, so 10% of a column ≈ 5% of a page)
+        from ark.latex_geometry import get_geometry
+        venue_format = self.config.get("venue_format", "")
+        geo = get_geometry(venue_format) if venue_format else {}
+        columns = geo.get("columns", 1)
+
+        if columns >= 2:
+            min_pages = venue_pages - 0.05  # double-column: right column 90% filled
+        else:
+            min_pages = venue_pages - 0.1   # single-column: last page 90% filled
+        max_pages = venue_pages + 0.1
         latex_dir = self.config.get("latex_dir", "paper")
 
-        self.log(f"[{context}] Page check: {page_count:.1f} body pages (target: {min_pages:.1f}–{max_pages:.1f})", "INFO")
+        self.log(f"[{context}] Page check: {page_count:.1f} body pages "
+                 f"(target: {min_pages:.2f}–{max_pages:.1f}, {columns}-col)", "INFO")
 
         # Case 1: Over limit → compress
         if page_count > max_pages:

ark/pipeline.py

@@ -406,9 +406,6 @@ def run_paper_iteration(self) -> bool:
             self.log_step_header(step_num, total_steps, "Validate", "end")
             self.save_step_checkpoint(step_num, "Validate")
 
-        # Final page count check after figure phase (figures may change layout)
-        self._enforce_page_count(context="post-validate-final")
-
         self.save_paper_state(paper_state)
         self._last_score = score
 
@@ -432,6 +429,9 @@ def run_paper_iteration(self) -> bool:
         self.log_step("Recompiling after improvements...", "progress")
         self.compile_latex()
 
+        # Hard page count enforcement — the ONLY place we enforce before delivery
+        self._enforce_page_count(context="pre-delivery")
+
         # Send iteration summary + PDF to Telegram
         self.send_iteration_summary(score, current_score, review_output)
 
@@ -1186,8 +1186,6 @@ def _run_dev_phase(self):
         self.log_step("Compiling initial draft...", "progress")
         if self.compile_latex():
             self.log_step("Initial draft compiled successfully", "success")
-            # Page count check after initial writing
-            self._enforce_page_count(context="dev-phase-initial-draft")
             # Send initial draft PDF via Telegram
             if self.telegram.is_configured:
                 pdf_path = self.latex_dir / "main.pdf"

ark/templates/agents/writer.prompt

@@ -48,17 +48,30 @@ When handling figure-related tasks, **you must first read** `{FIGURES_DIR}/figur
 
 ## Hard Page Limit — {VENUE_PAGES} pages (MANDATORY)
 
-The paper body (excluding references and appendix) **must not exceed {VENUE_PAGES} pages**. Exceeding this limit means automatic desk rejection.
+The paper body (excluding references and appendix) has a strict page target:
+- **Maximum**: {VENUE_PAGES} pages. Exceeding this means automatic desk rejection.
+- **Minimum**: The last page of body text must be at least 90% filled. A paper that is too short looks incomplete and will be scored lower by reviewers.
+  - For single-column templates: the last page should have no more than 10% whitespace at the bottom.
+  - For double-column templates: the right column on the last body page should be at least 90% filled.
 
-**Before making ANY change**, count the current page usage. Then follow these rules strictly:
+**Before making ANY change**, check current page count. Then:
 
-- **If already over {VENUE_PAGES} pages**: Your primary job is COMPRESSION. Do NOT add any new content until the paper is under the limit. Move non-essential sections to `\appendix`. Merge overlapping sections. Cut redundant prose.
-- **If at or near the limit**: For every paragraph you add, you MUST remove an equal or larger amount of text. Net content must NOT increase.
-- **If well under the limit**: You may add content, but always check page count after changes.
+- **Over {VENUE_PAGES} pages**: COMPRESS first. Do NOT add content until under the limit.
+- **At or near the limit**: For every paragraph added, remove equal or more text.
+- **Well under the limit (last page < 90% filled)**: ADD substantive content — deeper analysis, more related work comparisons, expanded methodology details. Do NOT pad with filler.
+
+**Always ensure `\clearpage` appears before `\bibliography`** so references start on a new page.
 
 **Compression strategies** (in order of priority):
 1. Move detailed ablations, sensitivity analyses, and per-category breakdowns to `\appendix`
 2. Merge Discussion and Conclusion into one section
 3. Replace verbose multi-paragraph explanations with concise text
 4. Compress tables — remove redundant rows/columns, use `\small` or `\footnotesize`
 5. Remove any content that repeats information from another section
+
+**Expansion strategies** (when too short):
+1. Deepen analysis/discussion — explain WHY, not just WHAT
+2. Add more related work with specific comparisons to your approach
+3. Expand experimental setup (hyperparameters, hardware, dataset splits)
+4. Add a Limitations paragraph
+5. Expand figure captions with interpretive context