# 490d research companion: C480–C1634

Prepared September 29, 2026. **C1634 is complete. C1635 has not begun.**

This ZIP gathers the substantive files produced in this conversation, the source updates needed to understand them, and the C480 bridge connecting them to your earlier archive. Documents remain separate and searchable. It includes the latest 30-page explanation PDF, its Markdown source, the technical companion PDF, diagrams, research records, models, calculations, verification evidence and historical drafts.

## What to give the new ChatGPT window

1. Your earlier **490d_C01_C479_Complete_Window_Archive_20260925.zip** (an uploaded copy may have `(4)` or another copy suffix).
2. This **490d_Chat_Companion_C480_C1634_20260929.zip**.
3. Your original repository/source files, if supplied separately from the older archive.

The earlier full archive was identified as 344,318,259 bytes. It was not repackaged or rerun for this handoff. Its own handoff and verification records remain part of the first package. The compact C479 restart kit is a convenience subset, not a substitute for the full older research archive. The small `_490d-unified-chronology.zip` contains only four Rounded source files (51a, 51b, 52a, 52b); those four are included here and are not the older research archive.

Read **01_RESEARCH_SITE_BRIEF_AND_NEW_WINDOW_PROMPT.md** and paste its final prompt into the new window. The Site is intended as a research workspace complementary to **490d.com**, with the Strategy's larger goal of explaining how the chronological families fit together.

## How to combine the packages

Extract the older archive and this companion into **separate folders**. Keep their internal paths intact. Build one catalog over both roots; do not flatten the files into one directory or overwrite equal basenames. Match duplicates by SHA-256 and retain their provenance. If your earlier ZIP already includes later cycles, keep the overlapping copies as history and use the current-file rules below.

This companion already expands the final evidence packages into `Research_Cycles/`, so the research can be indexed immediately. A nested C1431 reader ZIP remains inside its frozen evidence package because it is part of that original manifest; its readable documents also exist outside it. Repeated source snapshots within cycles intentionally preserve exact reproducible packages. Index identical contents once for search while retaining all source locations.

## Read these first

| File or folder | Purpose |
|---|---|
| `Source_Updates/Research_Strategy_v0_2.md` | Read the full guiding Strategy; its dated next-step discussion is historical. |
| `Current_Reader/490d_Chronological_Families_Explanation_Through_C1634_Portable.md` | Current connected explanation, with a working relative image link. |
| `Current_Reader/490d_Chronological_Families_Explanation_C1431_Print.pdf` | Latest printable explanation, **30 pages, through C1634**. |
| `Current_Reader/Strategy_Review_After_C1634.md` | Current assessment and next bounded research direction. |
| `Current_Reader/READING_ORDER.md` | Scope of the technical companion, map and other references. |
| `Research_Cycles/` | Complete numbered evidence from C480 through C1634. |
| `Reader_History/` and `Historical_Extras/` | Earlier editions, checkpoints and supplemental work; not the current starting point. |
| `Audit_and_Provenance/` | Completion audit, exact source-package identities and file inventory. |

## Source and version priority

- **Current explanation:** the original filename retains C1431, but the current main Markdown/PDF is the version extended through C1634. Use `Current_Reader/`, not an older same-named copy. Original source bytes remain frozen; the separately labelled portable Markdown changes only its diagram link.
- **Latest File52c:** `Source_Updates/File_52c_Latest_Controlling_Draft.md` is the latest, most thorough draft. It supersedes the older similarly named attachment for this phase. Preserve its Draft status.
- **Accepted comparison:** `Source_Updates/LXX_Reversed_Spines_and_Accepted_SP_Solution.md` controls the comparative-spine extension together with its later recorded refinements.
- **Original canonical documents:** keep their original identities and editions. Research reports explain and test them; they do not silently rewrite them. Old source snapshots remain valid evidence of what a particular earlier calculation used.
- **Scope:** deeper mirror analysis and inverse of the inverse remain deferred. The specifically authorized 2700-year Rounded shift to AD 2166 is included. Keep civil and Rounded epoch conventions distinct.

## Completion and recovery notes

The Round investigation began at C481, following the existing C480 checkpoint. C480 is included as a contextual bridge because the older complete archive ends at C479. The companion therefore covers **1,155 numbered actions, C480–C1634**; the work from C481 onward accounts for 1,154 of them. C-series numbers identify research actions, not literal files or independent discoveries. The supplied inventory gives actual file counts.

The interrupted C1132–C1431 cycle was completed. This package uses the recovered final 300-record evidence archive and its audit, not the stale working folder that stopped at C1291. There is no need to repeat that cycle. C531's frozen package contains an old `pending.json`; its complete 50-record journal and final verification establish completion. Historical pending files and old proposed next steps do not reset the current C1634 checkpoint.

Two damaged intermediate ZIP containers (through C791 and C891) were excluded; their completed work is in the valid final C831 and C931 packages. Exact duplicate checkpoint containers, repeated extraction trees, transfer helpers and temporary page-render caches were omitted. Unique substantive historical outputs and earlier delivered payload versions were retained. No chat transcript is claimed; this is the research-file archive.

## Integrity and reuse

`MANIFEST.json` records each payload's relative path, byte count and SHA-256. Run `python3 verify_companion.py` from the extracted companion folder to verify the archive's payloads. `Audit_and_Provenance/FILE_CATALOG.json` supplies titles, roles and cycle ranges for Site ingestion; `ORIGIN_MAP.json` maps earlier local/archive member names to preserved files. Cycle-local manifests and verifiers remain intact. The handoff verifies packaging and completion coverage; it does not claim a fresh rerun of every historical mathematical or historical conclusion.

Some original scripts and reports mention paths from the earlier workspace. Treat those strings as provenance. Resolve renamed source locations through the catalog, or run the supplied portable cycle verifiers from their preserved directories. Do not edit sealed journal entries or research manifests merely to make Site links work. Put navigational fixes and derived indexes in a separate Site layer.