fix: add provider retry policy

docs/concepts/retry.md

@@ -0,0 +1,58 @@
+---
+summary: "Retry policy for outbound provider calls"
+read_when:
+  - Updating provider retry behavior or defaults
+  - Debugging provider send errors or rate limits
+---
+# Retry policy
+
+## Goals
+- Retry per HTTP request, not per multi-step flow.
+- Preserve ordering by retrying only the current step.
+- Avoid duplicating non-idempotent operations.
+
+## Defaults
+- Attempts: 3
+- Max delay cap: 30000 ms
+- Jitter: 0.1 (10 percent)
+- Provider defaults:
+  - Telegram min delay: 400 ms
+  - Discord min delay: 500 ms
+
+## Behavior
+### Discord
+- Retries only on rate-limit errors (HTTP 429).
+- Uses Discord `retry_after` when available, otherwise exponential backoff.
+
+### Telegram
+- Retries on transient errors (429, timeout, connect/reset/closed, temporarily unavailable).
+- Uses `retry_after` when available, otherwise exponential backoff.
+- Markdown parse errors are not retried; they fall back to plain text.
+
+## Configuration
+Set retry policy per provider in `~/.clawdbot/clawdbot.json`:
+
+```json5
+{
+  telegram: {
+    retry: {
+      attempts: 3,
+      minDelayMs: 400,
+      maxDelayMs: 30000,
+      jitter: 0.1
+    }
+  },
+  discord: {
+    retry: {
+      attempts: 3,
+      minDelayMs: 500,
+      maxDelayMs: 30000,
+      jitter: 0.1
+    }
+  }
+}
+```
+
+## Notes
+- Retries apply per request (message send, media upload, reaction, poll, sticker).
+- Composite flows do not retry completed steps.