diff --git a/.assets/timeline-gantt.png b/.assets/timeline-gantt.png
index 005c9cd..e7f9d96 100644
Binary files a/.assets/timeline-gantt.png and b/.assets/timeline-gantt.png differ
diff --git a/CALENDAR.md b/CALENDAR.md
index 9adab1c..c2d29ba 100644
--- a/CALENDAR.md
+++ b/CALENDAR.md
@@ -41,7 +41,7 @@ Full untruncated version index.
 |   stable2512-3 | 1.21.3 | 2026-03-23 | 2026-03-23 |  | [Released](https://github.com/paritytech/polkadot-sdk/releases/tag/polkadot-stable2512-3) |
 |   stable2512-4 | 1.21.4 | 2026-04-20 | 2026-04-23 |  | ~~Cancelled~~ |
 |   stable2512-5 | 1.21.5 | 2026-05-21 | 2026-05-21 |  | [Released](https://github.com/paritytech/polkadot-sdk/releases/tag/polkadot-stable2512-5) |
-|   stable2512-6 | 1.21.6 | 2026-06-15 | 2026-06-18 |  | Planned |
+|   stable2512-6 | 1.21.6 | 2026-06-17 | 2026-06-17 |  | [Released](https://github.com/paritytech/polkadot-sdk/releases/tag/polkadot-stable2512-6) |
 |   stable2512-7 | 1.21.7 | 2026-07-20 | 2026-07-23 |  | Planned |
 |   stable2512-8 | 1.21.8 | 2026-08-17 | 2026-08-20 |  | Planned |
 |   stable2512-9 | 1.21.9 | 2026-09-21 | 2026-09-24 |  | Planned |
diff --git a/README.md b/README.md
index 360bc3d..5958fcc 100644
--- a/README.md
+++ b/README.md
@@ -31,11 +31,11 @@ Planned and historic release dates:
 |   stable2603-5 | 1.22.5 | 2026-07-27 | 2026-07-30 |  | Planned |
 |   [1 more past, 7 more planned](CALENDAR.md) |  |  | | |
 | **stable2512** | 1.21.0 | 2025-11-17 | 2025-12-22 | 2027-01-01 | [Released](https://github.com/paritytech/polkadot-sdk/releases/tag/polkadot-stable2512) |
-|   stable2512-4 | 1.21.4 | 2026-04-20 | 2026-04-23 |  | ~~Cancelled~~ |
 |   stable2512-5 | 1.21.5 | 2026-05-21 | 2026-05-21 |  | [Released](https://github.com/paritytech/polkadot-sdk/releases/tag/polkadot-stable2512-5) |
-|   stable2512-6 | 1.21.6 | 2026-06-15 | 2026-06-18 |  | Planned |
+|   stable2512-6 | 1.21.6 | 2026-06-17 | 2026-06-17 |  | [Released](https://github.com/paritytech/polkadot-sdk/releases/tag/polkadot-stable2512-6) |
 |   stable2512-7 | 1.21.7 | 2026-07-20 | 2026-07-23 |  | Planned |
-|   [3 more past, 5 more planned](CALENDAR.md) |  |  | | |
+|   stable2512-8 | 1.21.8 | 2026-08-17 | 2026-08-20 |  | Planned |
+|   [4 more past, 4 more planned](CALENDAR.md) |  |  | | |
 | **stable2509** | 1.20.0 | 2025-08-18 | 2025-10-08 | 2026-10-02 | [Released](https://github.com/paritytech/polkadot-sdk/releases/tag/polkadot-stable2509) |
 |   stable2509-8 | 1.20.8 | 2026-05-15 | 2026-05-15 |  | [Released](https://github.com/paritytech/polkadot-sdk/releases/tag/polkadot-stable2509-8) |
 |   stable2509-9 | 1.20.9 | 2026-06-11 | 2026-06-11 |  | [Released](https://github.com/paritytech/polkadot-sdk/releases/tag/polkadot-stable2509-9) |
diff --git a/releases-v1.ics b/releases-v1.ics
index c8215d7..1659f99 100644
--- a/releases-v1.ics
+++ b/releases-v1.ics
@@ -1386,17 +1386,17 @@ DESCRIPTION:Release of stable2512-5 (released)\n\nFull Calendar: https://g
 END:VEVENT
 BEGIN:VEVENT
 SUMMARY:stable2512-6 Cutoff
-DTSTART;VALUE=DATE:20260615
-DTEND;VALUE=DATE:20260616
-DESCRIPTION:Cutoff for stable2512-6 (planned)\n\nFull Calendar: https://gi
- thub.com/paritytech/release-registry/blob/main/CALENDAR.md#calendar
+DTSTART;VALUE=DATE:20260617
+DTEND;VALUE=DATE:20260618
+DESCRIPTION:Cutoff for stable2512-6 (released)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry/blob/main/CALENDAR.md#calendar
 END:VEVENT
 BEGIN:VEVENT
 SUMMARY:stable2512-6 Release
-DTSTART;VALUE=DATE:20260618
-DTEND;VALUE=DATE:20260619
-DESCRIPTION:Release of stable2512-6 (planned)\n\nFull Calendar: https://gi
- thub.com/paritytech/release-registry/blob/main/CALENDAR.md#calendar
+DTSTART;VALUE=DATE:20260617
+DTEND;VALUE=DATE:20260618
+DESCRIPTION:Release of stable2512-6 (released)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry/blob/main/CALENDAR.md#calendar
 END:VEVENT
 BEGIN:VEVENT
 SUMMARY:stable2512-7 Cutoff
diff --git a/releases-v1.json b/releases-v1.json
index 34f3120..1c414f9 100644
--- a/releases-v1.json
+++ b/releases-v1.json
@@ -1225,13 +1225,12 @@
           },
           {
             "name": "stable2512-6",
-            "cutoff": {
-              "estimated": "2026-06-15"
-            },
+            "cutoff": "2026-06-17",
             "publish": {
-              "estimated": "2026-06-18"
+              "when": "2026-06-17",
+              "tag": "polkadot-stable2512-6"
             },
-            "state": "planned",
+            "state": "released",
             "semver": "1.21.6"
           },
           {