diff --git a/README.md b/README.md
index 50381b4..f993ec7 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,14 @@ The model decides <em>when</em> and <em>what</em> to compress — not a hard lim
 
 ---
 
+## Community
+
+Discussion, help, and updates on QQ — one group covers all three projects (`billion-context`, `billion-context-pi`, `opencode-acp`):
+
+**QQ Group: 1056132097**
+
+---
+
 ## Why ACP
 
 ACP hands all context-management authority to the model itself — not relying on
diff --git a/README.zh-CN.md b/README.zh-CN.md
index 97f16cb..b62f795 100644
--- a/README.zh-CN.md
+++ b/README.zh-CN.md
@@ -22,6 +22,14 @@
 
 ---
 
+## 社区
+
+交流、求助与更新都在 QQ——同一个群覆盖三个项目(`billion-context`、`billion-context-pi`、`opencode-acp`):
+
+**QQ 群:1056132097**
+
+---
+
 ## 为什么选择 ACP
 
 ACP 将上下文管理的所有权限全部交给模型自己，而不依靠外部模型或各种复杂的机制去做上下文管理。它是迄今为止，市面上对上下文管理最好的实现。
diff --git a/devlog/2026-09-11_readme-qq-group/REQ.md b/devlog/2026-09-11_readme-qq-group/REQ.md
new file mode 100644
index 0000000..b263d0b
--- /dev/null
+++ b/devlog/2026-09-11_readme-qq-group/REQ.md
@@ -0,0 +1,30 @@
+# REQ - Add QQ community group to README (EN + ZH)
+
+- Task ID: `2026-09-11_readme-qq-group`
+- Home Repo: `opencode-acp`
+- Created: 2026-09-11
+- Status: Done
+- Priority: P2
+- Owner: ranxianglei
+- References: https://github.com/ranxianglei/billion-context/issues/698
+
+## 1. Background & Problem Statement
+
+- **Context**: The three sibling projects (`billion-context`, `billion-context-pi`, `opencode-acp`) share a single QQ community group (`1056132097`) for discussion, support, and updates. This is not surfaced in any README.
+- **Current behavior (symptom)**: Neither `README.md` nor `README.zh-CN.md` has a community/QQ section.
+- **Expected behavior**: A Community section in both language READMEs lists the shared QQ group and notes it covers all three projects.
+- **Impact**: Discoverability of the community channel only; no runtime/functional impact.
+
+## 3. Constraints & Non-Goals
+
+- **Constraints**:
+  - Docs-only; must not change `version` or any code/config.
+- **Non-Goals** (explicitly out of scope):
+  - No version bump, no CHANGELOG entry (no version change), no code changes.
+
+## 4. Acceptance Criteria (must be testable)
+
+- **Correctness**:
+  - [x] `README.md` has a `## Community` section listing **QQ Group: 1056132097**, placed near the top (before the first content section).
+  - [x] `README.zh-CN.md` has a `## 社区` section listing **QQ 群:1056132097**, placed near the top (before the first content section).
+- **Regression**: N/A — documentation only; no test-suite changes.
diff --git a/devlog/2026-09-11_readme-qq-group/WORKLOG.md b/devlog/2026-09-11_readme-qq-group/WORKLOG.md
new file mode 100644
index 0000000..3f09829
--- /dev/null
+++ b/devlog/2026-09-11_readme-qq-group/WORKLOG.md
@@ -0,0 +1,33 @@
+# WORKLOG - Add QQ community group to README (EN + ZH)
+
+- Task ID: `2026-09-11_readme-qq-group`
+- Home Repo: `opencode-acp`
+- Status: Done
+- Updated: 2026-09-11 17:05
+
+## 1. Summary
+
+- **What was done**: Added a "Community"/"社区" section to both `README.md` and `README.zh-CN.md`, listing the shared QQ group (`1056132097`) that covers `billion-context`, `billion-context-pi`, and `opencode-acp`.
+- **Why**: Users asked to surface the shared QQ community group across all three project READMEs, in both English and Chinese.
+- **Behavior / compatibility changes**: No — documentation only.
+- **Risk level**: Low
+
+## 2. Change Log
+
+### Key Files
+
+- `README.md` — added `## Community` section near the top (before the first content section).
+- `README.zh-CN.md` — added `## 社区` section near the top (before the first content section).
+
+## 4. Testing & Verification
+
+### Results
+
+- **PASS/FAIL**: PASS (docs-only; no build/test needed)
+- Verified diff touches only the two README files (+6 lines each); `package.json` version untouched.
+
+## 5. Risk Assessment & Rollback
+
+- **Risk points**: None functional.
+- **Rollback method**: Revert the single commit.
+- **Compatibility notes** (data format, config schema): No.