diff --git a/src/backend/mir_interpreter/handlers/calls/global.rs b/src/backend/mir_interpreter/handlers/calls/global.rs
index c9a1319e..052a4fcf 100644
--- a/src/backend/mir_interpreter/handlers/calls/global.rs
+++ b/src/backend/mir_interpreter/handlers/calls/global.rs
@@ -177,9 +177,32 @@ impl MirInterpreter {
                 Ok(VMValue::Void)
             }
             _ => {
+                // ⚠️ Phase 0.2: User-friendly "Did you mean?" suggestions
+                let prefix = if let Some(idx) = canonical.find('.') {
+                    &canonical[..idx]
+                } else {
+                    &canonical
+                };
+
+                let similar: Vec<_> = self.functions.keys()
+                    .filter(|k| k.starts_with(prefix))
+                    .take(5)
+                    .collect();
+
+                let mut err_msg = format!("Function not found: {}", func_name);
+
+                if !similar.is_empty() {
+                    err_msg.push_str("\n\n💡 Did you mean:");
+                    for s in similar {
+                        err_msg.push_str(&format!("\n   - {}", s));
+                    }
+                }
+
+                err_msg.push_str("\n\n🔍 Debug: NYASH_DEBUG_FUNCTION_LOOKUP=1 for full lookup trace");
+
                 // NamingBox SSOT: ここで canonical に失敗したら素直に Unknown とする。
                 // レガシーフォールバック（functions.get(func_name) 再探索）は Phase 25.x で廃止済み。
-                Err(self.err_with_context("global function", &format!("Unknown: {}", func_name)))
+                Err(self.err_with_context("global function", &err_msg))
             }
         }
     }
diff --git a/src/runner/modes/common_util/resolve/strip.rs b/src/runner/modes/common_util/resolve/strip.rs
index fd82fabb..b53301e6 100644
--- a/src/runner/modes/common_util/resolve/strip.rs
+++ b/src/runner/modes/common_util/resolve/strip.rs
@@ -352,12 +352,40 @@ pub fn collect_using_and_strip(
                         }
                     }
                 } else {
-                    return Err(format!(
-                        "{}:{}: using: '{}' not found in nyash.toml [using]/[modules]. Define a package or alias and use its name (prod profile)\n  suggestions: add an alias in nyash.toml and use 'using \"alias.name\" as Name'  |  dev/test: NYASH_PREINCLUDE=1",
-                        filename,
-                        line_no,
-                        target_unquoted
-                    ));
+                    // ⚠️ Phase 0.3: User-friendly "Did you mean?" suggestions
+                    let similar: Vec<_> = using_ctx.aliases.keys()
+                        .filter(|k| {
+                            k.to_lowercase().contains(&target_unquoted.to_lowercase()) ||
+                            target_unquoted.to_lowercase().contains(&k.to_lowercase())
+                        })
+                        .take(3)
+                        .collect();
+
+                    let mut err_msg = format!(
+                        "{}:{}: using: '{}' not found in nyash.toml [using]/[modules]",
+                        filename, line_no, target_unquoted
+                    );
+
+                    if !similar.is_empty() {
+                        err_msg.push_str("\n\n💡 Did you mean:");
+                        for s in similar {
+                            err_msg.push_str(&format!("\n   - {}", s));
+                        }
+                    }
+
+                    if using_ctx.aliases.is_empty() {
+                        err_msg.push_str("\n\n⚠️  No aliases loaded (check TOML parse errors above)");
+                    } else {
+                        err_msg.push_str(&format!("\n\nAvailable modules: {} aliases", using_ctx.aliases.len()));
+                    }
+
+                    err_msg.push_str("\n\n📝 Suggestions:");
+                    err_msg.push_str("\n   - Add an alias in nyash.toml: [using.aliases] YourModule = \"path/to/module\"");
+                    err_msg.push_str("\n   - Use the alias: using YourModule as YourModule");
+                    err_msg.push_str("\n   - Dev/test mode: NYASH_PREINCLUDE=1");
+                    err_msg.push_str("\n\n🔍 Debug: NYASH_DEBUG_USING=1 for detailed logs");
+
+                    return Err(err_msg);
                 }
             } else {
                 // dev/ci: allow broader resolution via resolver
diff --git a/src/runner/pipeline.rs b/src/runner/pipeline.rs
index 04e0a751..b13e510c 100644
--- a/src/runner/pipeline.rs
+++ b/src/runner/pipeline.rs
@@ -54,6 +54,16 @@ impl NyashRunner {
             }
         }
 
+        // ⚠️ Phase 0.1: Immediate error display for TOML parse failures
+        if let Err(e) = &toml_result {
+            eprintln!("⚠️  [using/workspace] Failed to load TOML modules:");
+            eprintln!("    Error: {}", e);
+            eprintln!("    → All 'using' aliases will be unavailable");
+            eprintln!("    → Fix TOML syntax errors in workspace modules");
+            eprintln!();
+            eprintln!("    💡 Debug: NYASH_DEBUG_USING=1 for detailed logs");
+        }
+
         // Env overrides: modules and using paths
         if let Ok(ms) = std::env::var("NYASH_MODULES") {
             for ent in ms.split(',') {