diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
index d9ebc1d..e00be94 100644
--- a/DEVELOPMENT.md
+++ b/DEVELOPMENT.md
@@ -62,6 +62,14 @@ server response bodies.
 stores it. Validation always uses the default endpoint, even if a user
 overrides `baseUrl` in `models.json`.
 
+## Compatibility
+
+Supported: pi 1.3 and newer (`peerDependencies`). Development pins pi 1.5.
+On 1.0–1.2 the tests pass and a live session worked, but `pnpm run check`
+fails: pi's `Provider` typing rejects this provider, and 1.0–1.1 also lack
+`RefreshModelsContext.baseUrl`, so `baseUrl` overrides are ignored there. To check another version, pin both
+`@earendil-works/*` dev dependencies to it and run `pnpm run ci`.
+
 ## Known server-side issues
 
 As of November 2026, `gpt-5-nano` and `gpt-4.1-nano` return HTTP 500
diff --git a/README.md b/README.md
index 775a040..cf2771e 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ streaming responses, and image input all work.
 
 ## What you need
 
-- **pi 1.5 or newer** ([installation guide](https://pi.dev))
+- **pi 1.3 or newer** ([installation guide](https://pi.dev))
 - **A uniGPT API key.** If you don't have one, ask the uniGPT team at the
   [IDea_Lab](https://idea-lab.uni-graz.at/en/digital-innovation-lab/unigpt-and-studigpt).
 
diff --git a/package.json b/package.json
index 37a522f..a4beb2f 100644
--- a/package.json
+++ b/package.json
@@ -41,8 +41,8 @@
     "ci": "pnpm run check && pnpm test"
   },
   "peerDependencies": {
-    "@earendil-works/pi-ai": ">=1.5.0 <2",
-    "@earendil-works/pi-coding-agent": ">=1.5.0 <2"
+    "@earendil-works/pi-ai": ">=1.3.0 <2",
+    "@earendil-works/pi-coding-agent": ">=1.3.0 <2"
   },
   "devDependencies": {
     "@earendil-works/pi-ai": "1.5.0",