diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 00000000..0013601c
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,48 @@
+# .gitattributes
+# Controls git archive exports and helps categorize repo contents.
+# export-ignore: excluded from `git archive` tarballs and sparse-export contexts.
+#
+# For agents blocked by repo size on clone, see CONTRIBUTING.md §"Large-Repo Clone Strategy".
+
+# ── Documentation & reports (not needed for runtime or tests) ──────────────────
+docs/               export-ignore
+reports/            export-ignore
+audits/             export-ignore
+reviews/            export-ignore
+paper/              export-ignore
+scaffold/           export-ignore
+playground/         export-ignore
+examples/           export-ignore
+intelligence/       export-ignore
+
+# Root-level narrative docs (keep CLAUDE.md, README.md, CONTRIBUTING.md)
+FINDINGS-*.md       export-ignore
+FIRST_LIGHT_REPORT*.md  export-ignore
+INVESTIGATION_*.md  export-ignore
+LEGACY_MATRIX_AUDIT.md  export-ignore
+SOUL.md             export-ignore
+POLICY.md           export-ignore
+BROWSER_CONTRACT.md export-ignore
+EVENNIA_NEXUS_EVENT_PROTOCOL.md  export-ignore
+GAMEPORTAL_PROTOCOL.md  export-ignore
+DEVELOPMENT.md      export-ignore
+
+# ── Operation-specific directories ────────────────────────────────────────────
+operation-get-a-job/  export-ignore
+operations/           export-ignore
+org/                  export-ignore
+concept-packs/        export-ignore
+evolution/            export-ignore
+
+# ── Assets (binary/media files not needed for CI) ─────────────────────────────
+assets/             export-ignore
+icons/              export-ignore
+
+# ── Linguist overrides (GitHub/Gitea language stats) ──────────────────────────
+docs/               linguist-documentation
+scaffold/           linguist-documentation
+paper/              linguist-documentation
+reports/            linguist-documentation
+audits/             linguist-documentation
+
+*.md                linguist-documentation
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 70ccff2c..e23dab4d 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -136,6 +136,44 @@ Hotfixes require:
 
 ---
 
+## Large-Repo Clone Strategy
+
+Some repos in this org (hermes-agent, the-nexus as it grows) can exceed 1000 tracked files, which causes `git clone --depth 1` to time out and also hits the Gitea tree-API cap of 1000 entries.
+
+### Recommended clone patterns for agents
+
+**Blobless partial clone** — fastest overall; metadata arrives immediately, blobs are fetched on demand:
+```sh
+git clone --filter=blob:none --depth 1 <repo-url>
+```
+
+**Treeless partial clone** — skips tree objects for past commits; best when you need full working tree but not history:
+```sh
+git clone --filter=tree:0 <repo-url>
+```
+
+**Sparse checkout** — only materialise the subdirectories you actually need:
+```sh
+git clone --filter=blob:none --no-checkout <repo-url> myrepo
+cd myrepo
+git sparse-checkout init --cone
+git sparse-checkout set nexus tests          # only check out these dirs
+git checkout main
+```
+
+### Gitea tree API workaround
+
+When the tree endpoint returns exactly 1000 entries and you suspect truncation, pass `recursive=1` and page through with the `page` parameter:
+```
+GET /api/v1/repos/{owner}/{repo}/git/trees/{sha}?recursive=1&page=2
+```
+
+### Why `.gitattributes` export-ignore exists
+
+Directories marked `export-ignore` in `.gitattributes` are excluded from `git archive` tarballs and future sparse-export tooling. This reduces the surface area for export-based agent workflows. It does **not** affect `git clone` directly — use the partial-clone flags above for that.
+
+---
+
 ## Stale PR Policy
 
 A cron job runs every 6 hours and auto-closes PRs that are: