feat: add session resumption support for Copilot CLI and update related configurations

Author: DevelopmentCats

registry/coder-labs/modules/copilot-cli/README.md

@@ -34,9 +34,9 @@ module "copilot_cli" {
 
 ## Examples
 
-### Usage with Tasks (Recommended for Development)
+### Usage with Tasks
 
-For development environments where you want Copilot CLI to have full access to tools without prompting:
+For development environments where you want Copilot CLI to have full access to tools and automatically resume sessions:
 
 ```tf
 data "coder_parameter" "ai_prompt" {
@@ -56,6 +56,7 @@ module "copilot_cli" {
   ai_prompt       = data.coder_parameter.ai_prompt.value
   copilot_model   = "claude-sonnet-4.5"
   allow_all_tools = true
+  resume_session  = true
 
   system_prompt = <<-EOT
     You are a helpful AI coding assistant working in a development environment.
@@ -205,6 +206,26 @@ This module works with multiple GitHub authentication methods in priority order:
 
 > **Note**: OAuth tokens work best with Copilot CLI. Personal Access Tokens may have limited functionality.
 
+## Session Resumption
+
+By default (`resume_session = true`), this module automatically resumes the latest Copilot CLI session when the workspace is restarted. This provides a seamless experience where:
+
+- **Previous conversations continue** - No need to re-establish context
+- **No duplicate prompts** - Initial prompts are only sent on first workspace creation
+- **Workspace restart handling** - Automatically detects and resumes existing sessions
+
+```tf
+module "copilot_cli" {
+  source   = "registry.coder.com/coder-labs/copilot-cli/coder"
+  version  = "1.0.0"
+  agent_id = coder_agent.example.id
+  workdir  = "/home/coder/project"
+
+  resume_session = true # Default: automatically resume sessions
+  # resume_session = false  # Always start fresh sessions
+}
+```
+
 ## Task Reporting
 
 When `report_tasks = true` (default), this module automatically configures and starts the **Coder MCP server** for task reporting integration:

registry/coder-labs/modules/copilot-cli/main.test.ts

@@ -309,4 +309,20 @@ describe("copilot-cli module", async () => {
     expect(githubTokenEnv.name).toBe("GITHUB_TOKEN");
     expect(githubTokenEnv.value).toBe("test_github_token_123");
   });
+
+  it("supports resume session configuration", async () => {
+    const resumeSessionVars = {
+      ...requiredVars,
+      resume_session: false,
+    };
+
+    const state = await runTerraformApply(moduleDir, resumeSessionVars);
+
+    const statusSlugEnv = findResourceInstance(
+      state,
+      "coder_env",
+      "mcp_app_status_slug",
+    );
+    expect(statusSlugEnv).toBeDefined();
+  });
 });

registry/coder-labs/modules/copilot-cli/main.tf

@@ -149,6 +149,12 @@ variable "cli_app_display_name" {
   default     = "Copilot CLI"
 }
 
+variable "resume_session" {
+  type        = bool
+  description = "Whether to automatically resume the latest Copilot CLI session on workspace restart."
+  default     = true
+}
+
 variable "pre_install_script" {
   type        = string
   description = "Custom script to run before configuring Copilot CLI."
@@ -237,6 +243,7 @@ module "agentapi" {
     ARG_DENY_TOOLS='${join(",", var.deny_tools)}' \
     ARG_TRUSTED_DIRECTORIES='${join(",", var.trusted_directories)}' \
     ARG_EXTERNAL_AUTH_ID='${var.external_auth_id}' \
+    ARG_RESUME_SESSION='${var.resume_session}' \
     /tmp/start.sh
   EOT
 

registry/coder-labs/modules/copilot-cli/scripts/install.sh

@@ -137,13 +137,11 @@ setup_coder_mcp_server() {
 #!/usr/bin/env bash
 set -e
 
-# --- Set environment variables ---
 export CODER_MCP_APP_STATUS_SLUG="${ARG_MCP_APP_STATUS_SLUG}"
 export CODER_MCP_AI_AGENTAPI_URL="http://localhost:3284"
 export CODER_AGENT_URL="${CODER_AGENT_URL}"
 export CODER_AGENT_TOKEN="${CODER_AGENT_TOKEN}"
 
-# --- Launch the MCP server ---
 exec coder exp mcp server
 EOF
   )
@@ -197,6 +195,16 @@ add_custom_mcp_servers() {
   fi
 }
 
+configure_copilot_model() {
+  if [ -n "$ARG_COPILOT_MODEL" ] && [ "$ARG_COPILOT_MODEL" != "claude-sonnet-4" ]; then
+    echo "Setting Copilot CLI model to: $ARG_COPILOT_MODEL"
+    copilot config model "$ARG_COPILOT_MODEL" || {
+      echo "WARNING: Failed to set model via copilot config, will use environment variable fallback"
+      export COPILOT_MODEL="$ARG_COPILOT_MODEL"
+    }
+  fi
+}
+
 configure_coder_integration() {
   if [ "$ARG_REPORT_TASKS" = "true" ] && [ -n "$ARG_MCP_APP_STATUS_SLUG" ]; then
     echo "Configuring Copilot CLI task reporting..."
@@ -214,6 +222,7 @@ validate_prerequisites
 install_copilot_cli
 check_github_authentication
 setup_copilot_configurations
+configure_copilot_model
 configure_coder_integration
 
 echo "Copilot CLI module setup completed."

registry/coder-labs/modules/copilot-cli/scripts/start.sh

@@ -17,6 +17,7 @@ ARG_ALLOW_TOOLS=${ARG_ALLOW_TOOLS:-}
 ARG_DENY_TOOLS=${ARG_DENY_TOOLS:-}
 ARG_TRUSTED_DIRECTORIES=${ARG_TRUSTED_DIRECTORIES:-}
 ARG_EXTERNAL_AUTH_ID=${ARG_EXTERNAL_AUTH_ID:-github}
+ARG_RESUME_SESSION=${ARG_RESUME_SESSION:-true}
 
 validate_copilot_installation() {
   if ! command_exists copilot; then
@@ -62,23 +63,17 @@ Task: $ARG_AI_PROMPT"
   fi
 }
 
-configure_copilot_model() {
-  if [ -n "$ARG_COPILOT_MODEL" ]; then
-    case "$ARG_COPILOT_MODEL" in
-      "gpt-5")
-        export COPILOT_MODEL="gpt-5"
-        ;;
-      "claude-sonnet-4")
-        export COPILOT_MODEL="claude-sonnet-4"
-        ;;
-      "claude-sonnet-4.5")
-        export COPILOT_MODEL="claude-sonnet-4.5"
-        ;;
-      *)
-        echo "WARNING: Unknown model '$ARG_COPILOT_MODEL'. Using default."
-        ;;
-    esac
+check_existing_session() {
+  if [ "$ARG_RESUME_SESSION" = "true" ]; then
+    if copilot --help > /dev/null 2>&1; then
+      local session_dir="$HOME/.copilot/sessions"
+      if [ -d "$session_dir" ] && [ "$(ls -A "$session_dir" 2> /dev/null)" ]; then
+        echo "Found existing Copilot CLI sessions. Resume mode enabled."
+        return 0
+      fi
+    fi
   fi
+  return 1
 }
 
 setup_github_authentication() {
@@ -117,20 +112,22 @@ start_agentapi() {
   echo "Starting in directory: $ARG_WORKDIR"
   cd "$ARG_WORKDIR"
 
-  build_copilot_args
-
-  if [ ${#COPILOT_ARGS[@]} -gt 0 ]; then
-    echo "Copilot arguments: ${COPILOT_ARGS[*]}"
-    agentapi server --type claude --term-width 120 --term-height 40 -- copilot "${COPILOT_ARGS[@]}"
+  if check_existing_session; then
+    echo "Resuming latest Copilot CLI session..."
+    agentapi server --type claude --term-width 120 --term-height 40 -- copilot --resume
   else
-    agentapi server --type claude --term-width 120 --term-height 40 -- copilot
+    echo "Starting new Copilot CLI session..."
+    build_copilot_args
+
+    if [ ${#COPILOT_ARGS[@]} -gt 0 ]; then
+      echo "Copilot arguments: ${COPILOT_ARGS[*]}"
+      agentapi server --type claude --term-width 120 --term-height 40 -- copilot "${COPILOT_ARGS[@]}"
+    else
+      agentapi server --type claude --term-width 120 --term-height 40 -- copilot
+    fi
   fi
 }
 
-configure_copilot_model
-
-echo "COPILOT_MODEL=${ARG_COPILOT_MODEL:-${COPILOT_MODEL:-not set}}"
-
 setup_github_authentication
 validate_copilot_installation
 start_agentapi