diff --git a/functions/_synu_agents/claude.fish b/functions/_synu_agents/claude.fish
index 8dca740f58a70eff9c9fc1278287d43c48b1059d..370449b4f139f692d5e8925b846b1524b1ee1e38 100644
--- a/functions/_synu_agents/claude.fish
+++ b/functions/_synu_agents/claude.fish
@@ -5,11 +5,25 @@
 # Claude Code agent definition for synu
 # Provides model configuration for routing through Synthetic API
 
-# Default models
-set -g _synu_claude_default_opus "hf:moonshotai/Kimi-K2-Thinking"
-set -g _synu_claude_default_sonnet "hf:MiniMaxAI/MiniMax-M2"
-set -g _synu_claude_default_haiku "hf:deepseek-ai/DeepSeek-V3.1-Terminus"
-set -g _synu_claude_default_subagent "hf:MiniMaxAI/MiniMax-M2"
+# Source cache functions
+source (status dirname)/../_synu_cache.fish
+
+# Fallback defaults (used when no cache entry exists)
+set -g _synu_claude_fallback_opus "hf:moonshotai/Kimi-K2-Thinking"
+set -g _synu_claude_fallback_sonnet "hf:MiniMaxAI/MiniMax-M2"
+set -g _synu_claude_fallback_haiku "hf:deepseek-ai/DeepSeek-V3.1-Terminus"
+set -g _synu_claude_fallback_agent "hf:MiniMaxAI/MiniMax-M2"
+
+function _synu_claude_default --description "Get default model: _synu_claude_default slot"
+    set -l slot $argv[1]
+    set -l cached (_synu_cache_get claude $slot)
+    if test $status -eq 0
+        echo $cached
+    else
+        set -l var_name _synu_claude_fallback_$slot
+        echo $$var_name
+    end
+end
 
 function _synu_agent_claude_flags --description "Return argparse-compatible flag specification"
     echo "L/large="
@@ -25,11 +39,11 @@ function _synu_agent_claude_configure --description "Configure Claude Code envir
     argparse 'L/large=' 'l/light=' 'o/opus=' 's/sonnet=' 'H/haiku=' 'a/agent=' -- $argv
     or return 1
 
-    # Start with defaults
-    set -l opus_model $_synu_claude_default_opus
-    set -l sonnet_model $_synu_claude_default_sonnet
-    set -l haiku_model $_synu_claude_default_haiku
-    set -l subagent_model $_synu_claude_default_subagent
+    # Start with defaults (from cache or fallback)
+    set -l opus_model (_synu_claude_default opus)
+    set -l sonnet_model (_synu_claude_default sonnet)
+    set -l haiku_model (_synu_claude_default haiku)
+    set -l subagent_model (_synu_claude_default agent)
 
     # Apply group overrides
     if set -q _flag_large
@@ -173,6 +187,31 @@ function _synu_agent_claude_interactive --description "Interactive model selecti
         end
     end
 
+    # Offer to save as defaults
+    if test (count $flags) -gt 0
+        if gum confirm "Save as default for 'claude'?"
+            for flag in $flags
+                # Parse --key=value format
+                set -l parts (string match -r '^--([^=]+)=(.+)$' $flag)
+                if test -n "$parts[2]"
+                    set -l key $parts[2]
+                    set -l value $parts[3]
+                    # Expand group flags to individual slots
+                    switch $key
+                        case large
+                            _synu_cache_set claude opus $value
+                            _synu_cache_set claude sonnet $value
+                            _synu_cache_set claude agent $value
+                        case light
+                            _synu_cache_set claude haiku $value
+                        case '*'
+                            _synu_cache_set claude $key $value
+                    end
+                end
+            end
+        end
+    end
+
     # Output flags for caller to use
     echo $flags
 end
diff --git a/functions/_synu_cache.fish b/functions/_synu_cache.fish
new file mode 100644
index 0000000000000000000000000000000000000000..3050ae8c8f60dedebba1215100cdc2e054b1cf80
--- /dev/null
+++ b/functions/_synu_cache.fish
@@ -0,0 +1,54 @@
+# SPDX-FileCopyrightText: Amolith <amolith@secluded.site>
+#
+# SPDX-License-Identifier: Unlicense
+
+# Cache management for synu model preferences
+# File format: agent.slot = model_id (one per line, # comments allowed)
+
+set -g _synu_cache_file (set -q XDG_CONFIG_HOME; and echo "$XDG_CONFIG_HOME"; or echo "$HOME/.config")"/synu/models.conf"
+
+function _synu_cache_get --description "Get a cached value: _synu_cache_get agent slot"
+    set -l agent $argv[1]
+    set -l slot $argv[2]
+    set -l key "$agent.$slot"
+
+    if not test -f "$_synu_cache_file"
+        return 1
+    end
+
+    # Match "key = value" or "key=value", ignoring comments and whitespace
+    set -l match (string match -r "^$key\\s*=\\s*(.+)" < "$_synu_cache_file")
+    if test -n "$match[2]"
+        string trim "$match[2]"
+        return 0
+    end
+    return 1
+end
+
+function _synu_cache_set --description "Set a cached value: _synu_cache_set agent slot value"
+    set -l agent $argv[1]
+    set -l slot $argv[2]
+    set -l value $argv[3]
+    set -l key "$agent.$slot"
+
+    # Ensure directory exists
+    mkdir -p (dirname "$_synu_cache_file")
+
+    if not test -f "$_synu_cache_file"
+        # Create new file with header
+        echo "# synu model preferences" > "$_synu_cache_file"
+        echo "# Format: agent.slot = model_id" >> "$_synu_cache_file"
+        echo "" >> "$_synu_cache_file"
+    end
+
+    # Check if key already exists
+    if string match -rq "^$key\\s*=" < "$_synu_cache_file"
+        # Replace existing line
+        set -l tmp (mktemp)
+        string replace -r "^$key\\s*=.*" "$key = $value" < "$_synu_cache_file" > "$tmp"
+        mv "$tmp" "$_synu_cache_file"
+    else
+        # Append new line
+        echo "$key = $value" >> "$_synu_cache_file"
+    end
+end