Root cause: LLM receiving full 34k-char JRXML would regenerate from scratch
instead of modifying coordinates in-place, shrinking output to ~3k chars.
Solution (programmatic node control, not prompt engineering):
- New agent/jrxml_windower.py: decompose JRXML into header (never sent to
LLM) + individual bands. Split bands >4000 chars at element boundaries.
Reassemble with element count validation (>10% change = rollback).
- Rewrite refine_layout: per-band windowed LLM processing (~2-4k chars
each). LLM cannot "reimagine" the entire report.
- Rewrite map_fields: 100% programmatic regex $F{field_N} -> real name
replacement. Zero LLM calls, zero content loss.
- _sanitize_field_name: non-ASCII chars escaped to _uXXXX_ format for
valid JRXML identifiers.
- Tests: 48 new unit tests (windower 28 + map_fields 20). All passing.
Full suite 385 tests, zero regressions.
- Replace truncated 12-char UUID with full 32-char UUID (128-bit entropy)
- Add validate_session_id() regex check to prevent path traversal
- Add _check_session_id() guard on all 6 API endpoints
- Change _step_counter from module global to contextvars.ContextVar
- Filter None values from node_state before merging into agent_state
- Log save_session failures instead of silently swallowing them
- Add finishStreaming() in catch/finally blocks to prevent UI lockup
- Fix broken multiline docstring in chat() endpoint
Root cause: layout_schema.regions is a list of region dicts, not a dict.
_log_ocr_layers() was calling .keys() on it, causing agent_error.
Also fixed: ProcessSection now stays visible after streaming ends (error or
completion), so generated content is not lost. Header shows ✓/✕/pulse indicators.
Error handler now refreshes session state for partial JRXML download.
Sidebar now has 快捷操作 section matching Streamlit app functionality:
- 预览 — sends "预览报表" to preview current JRXML
- 撤销 — sends "撤销上一步修改" to revert last change
- 重置 — sends "重新来，清空当前报表" to reset session
Session store now tracks history_states for undo availability check.
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