diff --git a/docs/backend/bill-diff-staging-coverage.md b/docs/backend/bill-diff-staging-coverage.md
new file mode 100644
index 00000000..4158e097
--- /dev/null
+++ b/docs/backend/bill-diff-staging-coverage.md
@@ -0,0 +1,212 @@
+# Bill Version Diff — Staging Coverage Run History (EPAC-2290)
+
+This file records deterministic evidence for the staging `GET /api/v1/bills/{id}/diff`
+endpoint: the exact commands run, the bill and version ids used, timestamps, and
+summarized outputs. It exists so [EPAC-2018](https://linear.app/riddimsoftware/issue/EPAC-2018/human-handoff-bills-votes-and-committees-depth)
+and future agents can reproduce the bill-versions spot-check without re-deriving it.
+
+> **Outcome of the 2026-06-14 run: the diff endpoint is reachable and returns the
+> documented "unavailable" response (HTTP 204) for every bill, because the bills
+> indexer currently produces diff *headers* but zero clause-level rows. The
+> 200 + non-empty `clauses` path cannot be exercised yet. Root cause and the
+> follow-up are in [Blocker](#blocker-200--clauses-is-not-yet-reachable) below.**
+
+## Environment
+
+| Field | Value |
+| --- | --- |
+| Staging API base URL | `https://staging-api.epac.riddimsoftware.com` |
+| AWS account | `227530433709` |
+| Bills artifact (S3) | `s3://epac-artifacts-227530433709/bills/v1/index.sqlite` (`BILLS_INDEX_PREFIX=bills/v1`) |
+| Live API Lambda | `epac-bills-staging` (downloads the S3 index at cold start, caches it in memory) |
+| Indexer | `backend/bills-indexer` (run via the `Data Ingestion` workflow, `run_bills_indexer` toggle) |
+
+## Primary smoke target
+
+Per EPAC-2290, the primary current-Parliament example is **C-11**, staging bill id
+`13608745`, "An Act to amend the National Defence Act and other Acts", parliament 45,
+session 1. It has three published versions:
+
+| Version id | Stage |
+| --- | --- |
+| `c-11-13615955-first-reading` | First Reading |
+| `c-11-13896514-as-amended-by-committee` | As amended by committee |
+| `c-11-14114368-as-passed-by-the-house-of-commons` | As passed by the House of Commons |
+
+> The bill depth endpoint resolves by **numeric id** (`/api/v1/bills/13608745`), not by
+> number (`/api/v1/bills/C-11` returns 404). The diff endpoint and the smoke fixtures
+> therefore use `13608745`. If parliamentary coverage shifts and C-11 is no longer a
+> valid multi-version example, rediscover a replacement from `GET /api/v1/bills` and
+> update this file plus the `bills:diff-*` fixtures in
+> `scripts/ci/backend_staging_smoke.py`.
+
+## Run, 2026-06-14
+
+### Step 1 — Re-run the bills indexer into staging
+
+```bash
+gh workflow run data-ingestion.yml --ref main -f environment=staging -f run_bills_indexer=true
+```
+
+Run: <https://github.com/RiddimSoftware/epac/actions/runs/27507169123>
+(dispatched `2026-06-14T17:52:40Z`, completed `success` `~17:54:42Z`).
+
+The indexer's `artifact_uploaded` log line (stderr, structured JSON):
+
+```json
+{"event":"artifact_uploaded","pipeline":"bills-indexer",
+ "sqlite_key":"bills/v1/index.sqlite",
+ "sqlite_sha256":"1b24feda8e1c967a635469c26648694ed74c5910290e9d5007b1e759ab06366a",
+ "sqlite_size_bytes":2523136,
+ "table_counts":{"bills":176,"bill_versions":251,"bill_diffs":77,
+                 "bill_clause_diffs":0,"bill_committee_stages":106,"pbo_costings":21},
+ "timestamp":"2026-06-14T17:54:42Z"}
+```
+
+`bill_diffs` = **77** (one header per adjacent version pair) but `bill_clause_diffs` = **0**.
+
+### Step 2 — Inspect the produced artifact
+
+```bash
+AWS_PROFILE=riddim-agent aws s3 cp \
+  s3://epac-artifacts-227530433709/bills/v1/index.sqlite /tmp/staging-bills.db --region us-east-1
+
+sqlite3 /tmp/staging-bills.db \
+  "SELECT 'bill_diffs',COUNT(*) FROM bill_diffs
+   UNION ALL SELECT 'bill_clause_diffs',COUNT(*) FROM bill_clause_diffs;"
+# bill_diffs|77
+# bill_clause_diffs|0
+```
+
+Version text is fetched only for the first and final stages, never the intermediate
+ones — so no two **adjacent** versions both carry text:
+
+```bash
+sqlite3 -header /tmp/staging-bills.db \
+  "SELECT stage_slug, COUNT(*) total,
+          SUM(CASE WHEN text_hash IS NOT NULL AND text_hash<>'' THEN 1 ELSE 0 END) with_text
+   FROM bill_versions GROUP BY stage_slug ORDER BY total DESC;"
+```
+
+| stage_slug | total | with_text |
+| --- | ---: | ---: |
+| first-reading | 167 | 167 |
+| as-passed-by-the-house-of-commons | 26 | 0 |
+| as-passed-by-the-senate | 24 | 0 |
+| as-amended-by-committee | 19 | 0 |
+| royal-assent | 15 | 15 |
+
+```bash
+# Adjacent (i, i+1 by sort_order) version pairs where BOTH sides have text.
+# buildDiffs() only diffs adjacent pairs, so this is the count of pairs that can
+# ever produce clauses.
+sqlite3 /tmp/staging-bills.db "
+WITH v AS (
+  SELECT bill_id,
+         CASE WHEN text_hash IS NOT NULL AND text_hash<>'' THEN 1 ELSE 0 END ht,
+         LEAD(CASE WHEN text_hash IS NOT NULL AND text_hash<>'' THEN 1 ELSE 0 END)
+           OVER (PARTITION BY bill_id ORDER BY sort_order) next_ht
+  FROM bill_versions)
+SELECT COUNT(*) FROM v WHERE ht=1 AND next_ht=1;"
+# 0
+```
+
+For C-11 specifically, only the first-reading version has text:
+
+```bash
+sqlite3 -header /tmp/staging-bills.db \
+  "SELECT id, CASE WHEN text_hash IS NOT NULL AND text_hash<>'' THEN 'Y' ELSE 'N' END has_text
+   FROM bill_versions WHERE bill_id='13608745' ORDER BY sort_order;"
+# c-11-13615955-first-reading|Y
+# c-11-13896514-as-amended-by-committee|N
+# c-11-14114368-as-passed-by-the-house-of-commons|N
+```
+
+### Step 3 — Live endpoint verification (after a Lambda cold start)
+
+The live Lambda caches the index in memory, so it was cold-started to pick up the
+freshly-ingested DB before verifying:
+
+```bash
+AWS_PROFILE=riddim-agent aws lambda update-function-configuration \
+  --function-name epac-bills-staging --region us-east-1 \
+  --description "EPAC-2290: cold-start to load freshly ingested bills.db (2026-06-14)"
+# wait for LastUpdateStatus=Successful
+```
+
+```bash
+base=https://staging-api.epac.riddimsoftware.com
+
+# Multi-version bill, real version ids -> 204 (no clauses available)
+curl -s -o /dev/null -w '%{http_code}\n' \
+  "$base/api/v1/bills/13608745/diff?from=c-11-13615955-first-reading&to=c-11-13896514-as-amended-by-committee"   # 204
+curl -s -o /dev/null -w '%{http_code}\n' \
+  "$base/api/v1/bills/13608745/diff?from=c-11-13896514-as-amended-by-committee&to=c-11-14114368-as-passed-by-the-house-of-commons"   # 204
+
+# One-version bill C-201 (13538627) -> 204 (documented unavailable behavior)
+curl -s -o /dev/null -w '%{http_code}\n' \
+  "$base/api/v1/bills/13538627/diff?from=c-201-13542332-first-reading&to=c-201-13542332-first-reading"   # 204
+
+# Zero-version bill C-1 (13539341), unknown version ids -> 204
+curl -s -o /dev/null -w '%{http_code}\n' \
+  "$base/api/v1/bills/13539341/diff?from=x&to=y"   # 204
+```
+
+### Step 4 — Existing staging smoke checks still pass
+
+```bash
+python3 scripts/ci/backend_staging_smoke.py --environment staging \
+  --base-url https://staging-api.epac.riddimsoftware.com
+# exit 0, 0 FAIL
+```
+
+| Check | Result |
+| --- | --- |
+| `bills:list` | PASS (HTTP 200) |
+| `bills:diff-route` | PASS (HTTP 400 for missing from/to) |
+| `members:list` | PASS (HTTP 200) |
+| `hansard-search` | PASS (HTTP 200) |
+| `cabinet-lobbying-overview` | PASS (HTTP 200) |
+| `lobbyist-organizations:directory` | PASS (HTTP 200) |
+
+## Acceptance-criteria status
+
+| Criterion | Status | Evidence |
+| --- | --- | --- |
+| Staging includes diff data for a multi-version current-Parliament bill | **Blocked** | Indexer produced 77 `bill_diffs` but 0 `bill_clause_diffs` (Step 1–2) |
+| Use C-11 (`13608745`) as the primary smoke target, or document a replacement | Met | C-11 still has three versions; designated in fixtures and here |
+| Multi-version bill `…/diff` returns 200 + non-empty `clauses` | **Blocked** | Returns 204 for every pair (Step 3) — no clause data exists to serve |
+| One-version / unsupported bill returns documented empty/unavailable (204) | Met | C-201 and C-1 return 204 (Step 3) |
+| Record exact commands, ids, version ids, timestamps, outputs | Met | This file |
+| Existing staging smoke checks continue to pass | Met | Contract smoke exit 0, 0 FAIL (Step 4) |
+
+## Blocker: 200 + clauses is not yet reachable
+
+The route, the OpenAPI contract, and the 204 "unavailable" path all work. What is
+missing is clause-level data, and that is produced upstream by the bills indexer
+(`backend/bills-indexer`), which EPAC-2290 explicitly depends on and does **not** own
+("Implementing the indexer diff algorithm" is out of scope).
+
+Two facts pin the cause to the indexer, not to source-data availability:
+
+1. The clause parser is fine. Running `parseBillXML` against the real C-11
+   first-reading XML yields **78 sections** with correct labels. The problem is that
+   **intermediate-stage version text is never ingested**: `fetchDocumentLinks` does not
+   discover an XML link from the `as-amended-by-committee` / `as-passed-*`
+   DocumentViewer pages, so those versions get no text (the stage table above: 0/19,
+   0/26, 0/24).
+2. The source XML exists. parl.ca serves the intermediate documents directly —
+   `https://www.parl.ca/Content/Bills/451/Government/C-11/C-11_2/C-11_E.xml` and
+   `…/C-11_3/C-11_E.xml` both return HTTP 200 — so this is a discovery gap in the
+   indexer, not a publication gap upstream.
+
+Because `buildDiffs` compares only strictly-adjacent versions and a text-less
+intermediate stage always sits between the two text-bearing stages, the number of
+adjacent pairs that both carry text is 0 across the whole dataset, so every diff has
+zero clauses and the endpoint returns 204.
+
+**To unblock**, the indexer needs to either (a) discover and ingest version text for
+the intermediate reading stages, or (b) diff the nearest text-bearing versions instead
+of strictly-adjacent ones. Both live in `backend/bills-indexer`. Tracked in the
+follow-up bug linked from the EPAC-2290 Linear issue. Once it lands, re-run Steps 1–4;
+the `bills:diff-full` smoke check (`--mode full`) is the gate that flips to green.
diff --git a/docs/backend/staging-smoke-tests.md b/docs/backend/staging-smoke-tests.md
index fb3be364..ae97bfb4 100644
--- a/docs/backend/staging-smoke-tests.md
+++ b/docs/backend/staging-smoke-tests.md
@@ -27,6 +27,7 @@ non-empty; fixture-dependent endpoints still accept empty result sets.
 | --- | --- | --- |
 | `GET /health` | Accepts `ok` or `degraded` `HealthResponse` JSON and fails DB/Lambda error bodies. | Seed/schedule pipeline health rows before requiring `ok`. |
 | `GET /api/v1/bills` | Verifies the bills envelope and requires a non-empty `bills` list from the published artifact. | No fixture required; the canonical bills artifact should not be empty after ingestion. |
+| `GET /api/v1/bills/{id}/diff` | Route check (`bills:diff-route`) asserts the service-owned HTTP 400 when `from`/`to` are missing — no diff data needed. Full mode (`--mode full`, `bills:diff-full`) asserts the seeded multi-version bill C-11 (`13608745`) returns 200 with a non-empty `clauses` array. | Full mode needs clause-level diff data from the bills indexer; see `docs/backend/bill-diff-staging-coverage.md`. As of 2026-06-14 the indexer emits diff headers but no `bill_clause_diffs`, so full mode stays red until that producer gap is fixed. |
 | `GET /api/v1/members` | Verifies the members envelope and requires a non-empty `members` list from the published artifact. | No fixture required; the canonical members artifact should not be empty after ingestion. |
 | `GET /api/v1/members/0/speeches` | Verifies pagination, stats, and speech-list contract with an empty-safe member id. | Seed a known MP and speech before asserting content. |
 | `GET /api/v1/members/0/votes` | Verifies pagination and vote-list contract with an empty-safe member id. | Seed member vote artifacts before asserting content. |
diff --git a/scripts/ci/backend_staging_smoke.py b/scripts/ci/backend_staging_smoke.py
index 96644633..048104e0 100755
--- a/scripts/ci/backend_staging_smoke.py
+++ b/scripts/ci/backend_staging_smoke.py
@@ -334,9 +334,14 @@ def validate_hansard_search_manifest(status: int, payload: Any) -> None:
         fixture_note="No fixture required; the current Parliament bills dataset should not be empty after ingestion.",
     ),
     SmokeCheck(
+        # Diff smoke target: C-11, staging bill id 13608745 (current Parliament,
+        # multiple versions). The depth/diff routes resolve by numeric id, not by
+        # bill number. If coverage shifts and C-11 is no longer a valid multi-version
+        # example, rediscover a replacement from GET /api/v1/bills and update both
+        # diff checks plus docs/backend/bill-diff-staging-coverage.md.
         name="bills:diff-route",
         method="GET",
-        path="/api/v1/bills/C-8/diff",
+        path="/api/v1/bills/13608745/diff",
         query={},
         expected_statuses={400, 404},
         validator=validate_bill_diff_route,
@@ -347,13 +352,20 @@ def validate_hansard_search_manifest(status: int, payload: Any) -> None:
     SmokeCheck(
         name="bills:diff-full",
         method="GET",
-        path="/api/v1/bills/C-8/diff",
-        query={"from": "C-8-v1", "to": "C-8-v3"},
+        path="/api/v1/bills/13608745/diff",
+        query={
+            "from": "c-11-13615955-first-reading",
+            "to": "c-11-13896514-as-amended-by-committee",
+        },
         expected_statuses={200, 404},
         validator=validate_bill_diff_payload,
         service="bills",
         deterministic_note="Full-mode check asserts a seeded current-Parliament multi-version bill returns a concrete diff payload.",
-        fixture_note="Requires C-8 diff data to be backfilled in the selected environment; skipped unless --mode full is used.",
+        fixture_note="Requires C-11 (13608745) clause-level diff data in the selected "
+        "environment. As of 2026-06-14 the bills indexer emits diff headers but no "
+        "bill_clause_diffs, so this returns 204 and full mode stays red until that "
+        "producer gap is fixed; see docs/backend/bill-diff-staging-coverage.md. "
+        "Skipped unless --mode full is used.",
         full_only=True,
     ),
     SmokeCheck(