diff --git a/.github/workflows/corpus.yml b/.github/workflows/corpus.yml
new file mode 100644
--- /dev/null
+++ b/.github/workflows/corpus.yml
@@ -0,0 +1,25 @@
+# Runs `gridcraft-cli check` over the pinned public-workbook corpus (corpus/) and reports the counts.
+# Not a required check: it is manual and weekly, and mismatches don't fail it (see corpus/README.md).
+name: Corpus
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "17 5 * * 1"
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    timeout-minutes: 45
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo build --release -p gridcraft-cli
+      - run: corpus/run.sh
+        env:
+          GRIDCRAFT_CLI: target/release/gridcraft-cli
diff --git a/ROADMAP.md b/ROADMAP.md
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -135,6 +135,7 @@ Ranked; estimates in Opus 5.5 agent-hours. Detail and the full beta-gate list in
 
 | Date | What landed |
 |---|---|
+| 2026-10-25 | A pinned corpus of 24 public Apache-2.0 workbooks (URLs and sha256 in `corpus/manifest.tsv`, never committed) and a non-required `Corpus` CI job that runs `gridcraft-cli check` over it weekly and on demand and reports the counts |
 | 2026-10-25 | AutoSum over a selection does what Excel does: a selected row gets one total to its right (in its last cell if that is empty), not a one-cell total under each cell; a block whose last column is empty gets each row's total there, one whose last row is empty each column's, and with both the corner gets the total of the block; otherwise totals go under each column as before |
 | 2026-10-24 | Go To lists the named ranges of every sheet (`Sheet2!Name` for a name scoped to another sheet; hidden names, constants and formulas left out) and the references entered before, a double-click goes to an entry, and the Reference box takes several names or references separated by commas (`Price, Type`, `B14:C22,F19:G30`) |
 | 2026-10-24 | Status bar: a right-click opens a menu that sets which selection statistics show (Average, Count and Sum by default; Numerical Count, Minimum and Maximum are new), kept with the preferences (`view.statusBar`) |
@@ -238,6 +239,7 @@ Ranked; estimates in Opus 5.5 agent-hours. Detail and the full beta-gate list in
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-25 | minor | Progress log: pinned public corpus CI job |
 | 2026-10-25 | minor | Progress log: AutoSum over a selected row, and a selection's empty last row and column |
 | 2026-10-23 | minor | Progress log: accounting negatives in number text |
 | 2026-10-23 | minor | Progress log: INDEX with one index on a 2-D reference is #REF! |
diff --git a/docs/gaps.md b/docs/gaps.md
--- a/docs/gaps.md
+++ b/docs/gaps.md
@@ -1,6 +1,6 @@
 # Gaps
 
-> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-24 · **Change:** minor (§8: PivotTable Enable show details; earlier: PivotTable Show Details) · **Target:** Microsoft Excel (Microsoft 365)
+> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-25 · **Change:** minor (§1: pinned public corpus CI job; earlier: PivotTable Enable show details) · **Target:** Microsoft Excel (Microsoft 365)
 
 Every known shortfall against Excel, one entry each, ranked by user impact (what blocks someone
 using GridCraft for real work first). This is the work list: pick from the top, check the open
@@ -17,7 +17,7 @@ No alpha blockers: every core workflow passes the [alpha gate](roadmap.md#alpha-
 
 
 ### 1. XLSX output not proven in Excel or on real files (FF)
-- **Missing:** a run over a real-world XLSX corpus, and confirmation that Excel opens what we save
+- **Missing:** a run over a larger real-world XLSX corpus (a pinned 24-file public set runs weekly in the non-required `Corpus` CI job, `corpus/`), and confirmation that Excel opens what we save
   with no repair prompt (PivotTables, charts, CF, validation, dynamic arrays, tables).
 - **Evidence:** round-trip tests cover our own files only (`crates/xlsx/src/tests/`); PivotTable
   round-trip noted as "unverified in real Excel" since 10-07; #64 (dynamic-array flag) shows the
@@ -181,6 +181,7 @@ No alpha blockers: every core workflow passes the [alpha gate](roadmap.md#alpha-
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-25 | minor | §1: pinned 24-file public workbook corpus and a non-required `Corpus` CI job running `gridcraft-cli check` over it |
 | 2026-10-24 | minor | §8: PivotTable Enable show details: `pivot.options` `enableShowDetails` turns Show Details off for a PivotTable, read and written in XLSX as `enableDrill` |
 | 2026-10-23 | minor | §8: PivotTable Show Details: double-clicking a value cell lists its source records on a new sheet (#2364) |
 | 2026-10-20 | minor | §11: the Japanese catalog covers the dialogs, messages and menus — 943 keys (~43%), matching the pt-BR coverage; a test keeps the two catalogs in step |