From ef4647f1d324cff43bb444ef4df6c253faed0d52 Mon Sep 17 00:00:00 2001
From: t <t@tjp.lol>
Date: Fri, 12 Jun 2026 14:49:51 -0600
Subject: improve errors: retries, surfacing provider errors to the user

---
 libpanto/src/provider.zig | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

(limited to 'libpanto/src/provider.zig')

diff --git a/libpanto/src/provider.zig b/libpanto/src/provider.zig
index 8ea74f3..e83012d 100644
--- a/libpanto/src/provider.zig
+++ b/libpanto/src/provider.zig
@@ -102,6 +102,7 @@ pub fn isRetryableProviderError(err: anyerror) bool {
         error.ProviderServerError,
         error.ProviderTransport,
         error.ProviderStreamMalformed,
+        error.ProviderOverloaded,
         => true,
         else => false,
     };
@@ -217,6 +218,12 @@ pub const ProviderStream = struct {
         produce: *const fn (*anyopaque, *EventQueue) anyerror!ProduceStatus,
         /// Free the response and any owned state.
         deinit: *const fn (*anyopaque) void,
+        /// Optional: after a failed `produce`, return the provider's
+        /// diagnostic message for the failure (e.g. an Anthropic
+        /// `overloaded_error` message), borrowed for the lifetime of the
+        /// response. Null when the provider has nothing to add beyond the
+        /// classified error name.
+        last_error: ?*const fn (*anyopaque) ?[]const u8 = null,
     };
 
     /// Pump the response, appending decoded events to `out`. Errors are
@@ -228,6 +235,13 @@ pub const ProviderStream = struct {
     pub fn deinit(self: ProviderStream) void {
         self.vtable.deinit(self.ptr);
     }
+
+    /// The provider's diagnostic message for the most recent `produce`
+    /// failure, if any. Borrowed for the lifetime of the response.
+    pub fn lastError(self: ProviderStream) ?[]const u8 {
+        const f = self.vtable.last_error orelse return null;
+        return f(self.ptr);
+    }
 };
 
 /// Open one streaming provider turn against the active config snapshot,
-- 
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