diff --git a/crates/g3-cli/src/agent_mode.rs b/crates/g3-cli/src/agent_mode.rs
index e03ec04..8160ede 100644
--- a/crates/g3-cli/src/agent_mode.rs
+++ b/crates/g3-cli/src/agent_mode.rs
@@ -1,7 +1,6 @@
 //! Agent mode for G3 CLI - runs specialized agents with custom prompts.
 
 use anyhow::Result;
-use std::path::PathBuf;
 use tracing::debug;
 
 use g3_core::ui_writer::UiWriter;
@@ -15,21 +14,17 @@ use crate::embedded_agents::load_agent_prompt;
 use crate::ui_writer_impl::ConsoleUiWriter;
 use crate::interactive::run_interactive;
 use crate::template::process_template;
+use crate::project::{Project, load_and_validate_project};
+use crate::cli_args::CommonFlags;
 
 /// Run agent mode - loads a specialized agent prompt and executes a single task.
+/// 
+/// Uses `CommonFlags` for flags that apply across all modes, ensuring consistency.
 pub async fn run_agent_mode(
     agent_name: &str,
-    workspace: Option<PathBuf>,
-    config_path: Option<&str>,
-    _quiet: bool,
-    new_session: bool,
     task: Option<String>,
-    chrome_headless: bool,
-    safari: bool,
     chat: bool,
-    include_prompt_path: Option<PathBuf>,
-    no_auto_memory: bool,
-    acd_enabled: bool,
+    flags: CommonFlags,
 ) -> Result<()> {
     use g3_core::find_incomplete_agent_session;
     use g3_core::get_agent_system_prompt;
@@ -40,7 +35,7 @@ pub async fn run_agent_mode(
     let output = SimpleOutput::new();
 
     // Determine workspace directory (current dir if not specified)
-    let workspace_dir = workspace.unwrap_or_else(|| std::env::current_dir().unwrap_or_default());
+    let workspace_dir = flags.workspace.clone().unwrap_or_else(|| std::env::current_dir().unwrap_or_default());
 
     // Change to the workspace directory first so session scanning works correctly
     std::env::set_current_dir(&workspace_dir)?;
@@ -49,7 +44,7 @@ pub async fn run_agent_mode(
     // Skip session resume entirely when in chat mode (--agent --chat)
     let resuming_session = if chat {
         None // Chat mode always starts fresh
-    } else if new_session {
+    } else if flags.new_session {
         if !chat {
             output.print("\n🆕 Starting new session (--new-session flag set)");
             output.print("");
@@ -97,16 +92,16 @@ pub async fn run_agent_mode(
     print_workspace_path(&workspace_dir);
 
     // Load config
-    let mut config = g3_config::Config::load(config_path)?;
+    let mut config = g3_config::Config::load(flags.config.as_deref())?;
 
     // Apply chrome-headless flag override
-    if chrome_headless {
+    if flags.chrome_headless {
         config.webdriver.enabled = true;
         config.webdriver.browser = g3_config::WebDriverBrowser::ChromeHeadless;
     }
 
     // Apply safari flag override
-    if safari {
+    if flags.safari {
         config.webdriver.enabled = true;
         config.webdriver.browser = g3_config::WebDriverBrowser::Safari;
     }
@@ -120,10 +115,10 @@ pub async fn run_agent_mode(
     let memory_content_opt = read_workspace_memory(&workspace_dir);
 
     // Read include prompt early so we can show it in the status line
-    let include_prompt = read_include_prompt(include_prompt_path.as_deref());
+    let include_prompt = read_include_prompt(flags.include_prompt.as_deref());
 
     // Build and print status line showing what was loaded
-    let include_filename = include_prompt_path.as_ref()
+    let include_filename = flags.include_prompt.as_ref()
         .filter(|_| include_prompt.is_some())
         .and_then(|p| p.file_name())
         .map(|s| s.to_string_lossy().to_string());
@@ -181,10 +176,10 @@ pub async fn run_agent_mode(
 
     // Auto-memory is enabled by default in agent mode (unless --no-auto-memory is set)
     // This prompts the LLM to save discoveries to workspace memory after each turn
-    agent.set_auto_memory(!no_auto_memory);
+    agent.set_auto_memory(!flags.no_auto_memory);
     
     // Enable ACD (Aggressive Context Dehydration) if requested
-    if acd_enabled {
+    if flags.acd {
         agent.set_acd_enabled(true);
     }
 
@@ -244,15 +239,43 @@ pub async fn run_agent_mode(
 
     // If chat mode is enabled, run interactive loop instead of single task
     if chat {
+        // Load project if --project flag was specified
+        let initial_project: Option<Project> = if let Some(ref proj_path) = flags.project {
+            match load_and_validate_project(&proj_path.to_string_lossy(), &workspace_dir) {
+                Ok(cli_project) => {
+                    // Set project content in agent's system message
+                    if agent.set_project_content(Some(cli_project.content.clone())) {
+                        // Set project path on UI writer for path shortening
+                        let project_name = cli_project.path
+                            .file_name()
+                            .and_then(|n| n.to_str())
+                            .unwrap_or("project")
+                            .to_string();
+                        agent.ui_writer().set_project_path(cli_project.path.clone(), project_name);
+                        Some(cli_project)
+                    } else {
+                        eprintln!("Warning: Failed to set project content in agent context.");
+                        None
+                    }
+                }
+                Err(e) => {
+                    eprintln!("Error loading project: {}", e);
+                    std::process::exit(1);
+                }
+            }
+        } else {
+            None
+        };
+
         return run_interactive(
             agent,
             false, // show_prompt
             false, // show_code
             combined_content,
             &workspace_dir,
-            new_session,
+            flags.new_session,
             Some(agent_name),  // agent name for prompt (e.g., "butler>")
-            None, // initial_project (not supported in agent mode yet)
+            initial_project,
         )
         .await;
     }
diff --git a/crates/g3-cli/src/cli_args.rs b/crates/g3-cli/src/cli_args.rs
index e4f50a5..ce1df6b 100644
--- a/crates/g3-cli/src/cli_args.rs
+++ b/crates/g3-cli/src/cli_args.rs
@@ -3,6 +3,35 @@
 use clap::Parser;
 use std::path::PathBuf;
 
+/// Flags that apply across all execution modes (interactive, agent, autonomous).
+/// 
+/// When adding a new flag that should work in all modes, add it here instead of
+/// passing individual parameters to mode functions. This prevents bugs where a
+/// flag works in one mode but is forgotten in another.
+#[derive(Clone, Debug, Default)]
+pub struct CommonFlags {
+    /// Workspace directory
+    pub workspace: Option<PathBuf>,
+    /// Configuration file path
+    pub config: Option<String>,
+    /// Skip session resumption and force a new session
+    pub new_session: bool,
+    /// Suppress output/logging
+    pub quiet: bool,
+    /// Use Chrome in headless mode for WebDriver
+    pub chrome_headless: bool,
+    /// Use Safari for WebDriver
+    pub safari: bool,
+    /// Include additional prompt content from a file
+    pub include_prompt: Option<PathBuf>,
+    /// Disable automatic memory update reminder
+    pub no_auto_memory: bool,
+    /// Enable aggressive context dehydration
+    pub acd: bool,
+    /// Load a project from the given path at startup
+    pub project: Option<PathBuf>,
+}
+
 #[derive(Parser, Clone)]
 #[command(name = "g3")]
 #[command(about = "A modular, composable AI coding agent")]
@@ -127,3 +156,22 @@ pub struct Cli {
     #[arg(long, value_name = "PATH")]
     pub project: Option<PathBuf>,
 }
+
+impl Cli {
+    /// Extract common flags that apply across all execution modes.
+    /// This ensures flags like --project, --acd, --include-prompt work consistently.
+    pub fn common_flags(&self) -> CommonFlags {
+        CommonFlags {
+            workspace: self.workspace.clone(),
+            config: self.config.clone(),
+            new_session: self.new_session,
+            quiet: self.quiet,
+            chrome_headless: self.chrome_headless,
+            safari: self.safari,
+            include_prompt: self.include_prompt.clone(),
+            no_auto_memory: self.no_auto_memory,
+            acd: self.acd,
+            project: self.project.clone(),
+        }
+    }
+}
diff --git a/crates/g3-cli/src/lib.rs b/crates/g3-cli/src/lib.rs
index 32c68b3..4e8d30f 100644
--- a/crates/g3-cli/src/lib.rs
+++ b/crates/g3-cli/src/lib.rs
@@ -90,17 +90,9 @@ pub async fn run() -> Result<()> {
     if let Some(agent_name) = &cli.agent {
         return run_agent_mode(
             agent_name,
-            cli.workspace.clone(),
-            cli.config.as_deref(),
-            cli.quiet,
-            cli.new_session,
             cli.task.clone(),
-            cli.chrome_headless,
-            cli.safari,
             cli.chat,
-            cli.include_prompt.clone(),
-            cli.no_auto_memory,
-            cli.acd,
+            cli.common_flags(),
         )
         .await;
     }
diff --git a/crates/g3-cli/tests/cli_integration_test.rs b/crates/g3-cli/tests/cli_integration_test.rs
index b63994c..cbb94c5 100644
--- a/crates/g3-cli/tests/cli_integration_test.rs
+++ b/crates/g3-cli/tests/cli_integration_test.rs
@@ -305,3 +305,33 @@ fn test_no_auto_memory_in_help_output() {
         "Help output should mention --no-auto-memory flag"
     );
 }
+
+// =============================================================================
+// Test: Project option is accepted (including with agent mode)
+// =============================================================================
+
+#[test]
+fn test_project_option_accepted() {
+    let output = Command::new(get_g3_binary())
+        .args(["--project", "/tmp/myproject", "--help"])
+        .output()
+        .expect("Failed to execute g3 with project option");
+
+    assert!(
+        output.status.success(),
+        "--project option should be recognized"
+    );
+}
+
+#[test]
+fn test_project_option_with_agent_mode_accepted() {
+    let output = Command::new(get_g3_binary())
+        .args(["--agent", "butler", "--chat", "--project", "/tmp/myproject", "--help"])
+        .output()
+        .expect("Failed to execute g3 with agent and project options");
+
+    assert!(
+        output.status.success(),
+        "--project option should work with --agent --chat"
+    );
+}