diff --git a/.github/workflows/rust-ci.yml b/.github/workflows/rust-ci.yml
index b33d5eb..94879a9 100644
--- a/.github/workflows/rust-ci.yml
+++ b/.github/workflows/rust-ci.yml
@@ -68,4 +68,6 @@ jobs:
         uses: Swatinem/rust-cache@779680da715d629ac1d338a641029a2f4372abb5 # v2
 
       - name: Check build
-        run: cargo check --all-features
+        # NB: the `gui` feature pulls eframe/egui which raise MSRV above 1.85.
+        # Verify the default + non-GUI optional features compile on MSRV.
+        run: cargo check --features signing,http
diff --git a/Cargo.toml b/Cargo.toml
index c941029..bc88b75 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,7 +24,7 @@ chrono = "0.4"
 filetime = "0.2"
 encoding_rs = "0.8"
 crossterm = "0.29"
-eframe = "0.34"
+eframe = { version = "0.34", optional = true }
 rayon = "1.12"
 blake3 = { version = "1.8", features = ["mmap"] }
 sha2 = "0.11"
@@ -39,6 +39,9 @@ ureq = { version = "3.3", optional = true }
 default = []
 signing = ["ed25519-dalek"]
 http = ["ureq"]
+# Native GUI viewer (eframe/egui). Opt-in because eframe raises MSRV above the
+# 1.85.0 baseline; default builds remain pure-CLI and MSRV-clean.
+gui = ["eframe"]
 
 [dev-dependencies]
 tempfile = "3.27"
diff --git a/src/main.rs b/src/main.rs
index 90a2210..b4009e8 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -468,7 +468,8 @@ enum Commands {
         headless: bool,
     },
 
-    /// GUI review of a saved report
+    /// GUI review of a saved report (requires `--features gui` at build time)
+    #[cfg(feature = "gui")]
     Gui {
         /// Assault report JSON file
         #[arg(value_name = "REPORT")]
@@ -1700,6 +1701,7 @@ fn run_main() -> Result<()> {
             }
         }
 
+        #[cfg(feature = "gui")]
         Commands::Gui { report, headless } => {
             let content = read_report_bounded(&report)?;
             let assault_report: AssaultReport = serde_json::from_str(&content)?;
diff --git a/src/report/mod.rs b/src/report/mod.rs
index 74f3c1b..d933d4a 100644
--- a/src/report/mod.rs
+++ b/src/report/mod.rs
@@ -5,6 +5,7 @@
 pub mod diff;
 pub mod formatter;
 pub mod generator;
+#[cfg(feature = "gui")]
 pub mod gui;
 pub mod migration;
 pub mod output;
@@ -19,6 +20,7 @@ use std::path::Path;
 pub use diff::{format_diff, load_report};
 pub use formatter::{ReportFormatter, ReportView};
 pub use generator::ReportGenerator;
+#[cfg(feature = "gui")]
 pub use gui::ReportGui;
 pub use output::ReportOutputFormat;
 pub use tui::ReportTui;