diff --git a/crates/sylpheed-formats/examples/default_owners.rs b/crates/sylpheed-formats/examples/default_owners.rs
index c1f64db2..820b6882 100644
--- a/crates/sylpheed-formats/examples/default_owners.rs
+++ b/crates/sylpheed-formats/examples/default_owners.rs
@@ -25,8 +25,12 @@ fn is_value(s: &str) -> bool {
 }
 
 fn main() {
-    let root = std::env::var("SYLPHEED_DISC")
-        .unwrap_or_else(|_| "/home/fabi/RE - Project Sylpheed/sylph_extract".into());
+    // No hardcoded fallback: it made SYLPHEED_DISC look like a control while
+    // one machine's directory layout decided the outcome (#16).
+    let Ok(root) = std::env::var("SYLPHEED_DISC") else {
+        eprintln!("set SYLPHEED_DISC to the extracted disc root");
+        std::process::exit(2);
+    };
     let wanted: Vec<String> = std::env::args().skip(1).collect();
     let arc = PakArchive::open(std::path::Path::new(&root).join("dat/GP_MAIN_GAME_E.pak")).unwrap();
 
diff --git a/crates/sylpheed-formats/examples/defaulted_fields.rs b/crates/sylpheed-formats/examples/defaulted_fields.rs
index 3a554eea..379bf08d 100644
--- a/crates/sylpheed-formats/examples/defaulted_fields.rs
+++ b/crates/sylpheed-formats/examples/defaulted_fields.rs
@@ -31,9 +31,14 @@ fn is_value(s: &str) -> bool {
 }
 
 fn main() {
+    // argv[1], else SYLPHEED_DISC. No hardcoded fallback -- see #16.
     let root = std::env::args()
         .nth(1)
-        .unwrap_or_else(|| "/home/fabi/RE - Project Sylpheed/sylph_extract".into());
+        .or_else(|| std::env::var("SYLPHEED_DISC").ok())
+        .unwrap_or_else(|| {
+            eprintln!("usage: defaulted_fields <disc-root> [paks...]   (or set SYLPHEED_DISC)");
+            std::process::exit(2);
+        });
     let paks: Vec<String> = std::env::args().skip(2).collect();
     let paks = if paks.is_empty() {
         vec![
diff --git a/crates/sylpheed-formats/tests/caption_families_disc.rs b/crates/sylpheed-formats/tests/caption_families_disc.rs
index f344c998..d3f4f199 100644
--- a/crates/sylpheed-formats/tests/caption_families_disc.rs
+++ b/crates/sylpheed-formats/tests/caption_families_disc.rs
@@ -4,31 +4,11 @@
 //! `build_caption_text` generalises the key parser to all eight.
 
 use std::collections::BTreeMap;
-use std::path::{Path, PathBuf};
 
 use sylpheed_formats::{movie_subtitle, PakArchive};
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let d = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    d.join("dat").is_dir().then(|| d.to_path_buf())
-}
-
-macro_rules! skip_without_disc {
-    ($root:ident) => {
-        let Some($root) = disc_root() else {
-            eprintln!("SKIP: set SYLPHEED_DISC");
-            return;
-        };
-    };
-}
+mod common;
+use common::skip_without_disc;
 
 #[test]
 fn all_eight_caption_families_are_read() {
diff --git a/crates/sylpheed-formats/tests/common/mod.rs b/crates/sylpheed-formats/tests/common/mod.rs
new file mode 100644
index 00000000..649e016f
--- /dev/null
+++ b/crates/sylpheed-formats/tests/common/mod.rs
@@ -0,0 +1,79 @@
+//! One place that decides where the disc corpora are — issue #16, remedy (3).
+//!
+//! # What this replaces
+//!
+//! Seventeen files under `tests/` each defined their own `disc_root()`, and they
+//! had **already drifted into five variants**. Four were the same thing written
+//! four ways (differing only in return type and style). The fifth —
+//! `movie_manifest_disc`, `movie_subtitle_disc`, `slb_disc` — did something
+//! materially different: it honoured `SYLPHEED_DISC` **and nothing else**.
+//!
+//! So one function name meant two different things in one directory, which is
+//! the same "one name, several meanings" defect #16 identifies in
+//! `SYLPHEED_DISC` itself and in `#[ignore]`.
+//!
+//! # Why the env var, and no fallback
+//!
+//! The fourteen copies with a fallback hardcoded one machine's absolute layout:
+//!
+//! ```text
+//! /home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)
+//! ```
+//!
+//! That made `unset SYLPHEED_DISC` a no-op there: whether the disc suites ran
+//! was a property of *the machine's directory layout*, invisible in the command
+//! and in the output. The env var looked like a control and was not one.
+//!
+//! This module adopts the behaviour three of those files already had, rather
+//! than inventing a new one: **the environment decides, always.** Point
+//! `SYLPHEED_DISC` at the extracted disc and the suites run; leave it unset and
+//! they skip. Same command, same answer, on every machine.
+//!
+//! `just test-disc` reads `.env` (already gitignored as a local dev override)
+//! so no absolute path has to live in the source tree again.
+//!
+//! # This does not fix the tally
+//!
+//! A skipped suite still counts as `passed` — `#[ignore]` is static and cannot
+//! move at runtime. That is why `tests/corpus_report.rs` exists: it prints which
+//! corpora resolved, and it is the thing to read. This module only makes the
+//! *control* honest, so that report can now say `PRESENT via $SYLPHEED_DISC`
+//! and mean it.
+// `tests/common/mod.rs` is compiled into EVERY integration-test binary, and each
+// one uses only the resolver (and maybe the macro) it needs. Without these, every
+// binary warns about the parts it did not use.
+#![allow(dead_code, unused_macros, unused_imports)]
+
+use std::path::PathBuf;
+
+/// The extracted disc root — the directory containing `dat/`.
+pub fn disc_root() -> Option<PathBuf> {
+    let p = PathBuf::from(std::env::var("SYLPHEED_DISC").ok()?);
+    p.join("dat").is_dir().then_some(p)
+}
+
+/// The extracted `resource3d` directory (`Stage_SNN.xpr` models).
+pub fn res3d_dir() -> Option<PathBuf> {
+    let p = PathBuf::from(std::env::var("SYLPHEED_RES3D").ok()?);
+    p.is_dir().then_some(p)
+}
+
+/// The retail ISO image itself, not a directory.
+pub fn iso_path() -> Option<PathBuf> {
+    let p = PathBuf::from(std::env::var("SYLPHEED_ISO").ok()?);
+    p.is_file().then_some(p)
+}
+
+/// Bind the disc root or return from the test.
+///
+/// The early return keeps the test *passing*, which is why the tally cannot
+/// distinguish a skip from a real run — see `corpus_report.rs`.
+macro_rules! skip_without_disc {
+    ($root:ident) => {
+        let Some($root) = crate::common::disc_root() else {
+            eprintln!("SKIP: set SYLPHEED_DISC to the extracted disc root");
+            return;
+        };
+    };
+}
+pub(crate) use skip_without_disc;
diff --git a/crates/sylpheed-formats/tests/corpus_report.rs b/crates/sylpheed-formats/tests/corpus_report.rs
index cc6221f6..e69da0b2 100644
--- a/crates/sylpheed-formats/tests/corpus_report.rs
+++ b/crates/sylpheed-formats/tests/corpus_report.rs
@@ -3,94 +3,62 @@
 //! # Why this exists
 //!
 //! `cargo test --workspace` reports **the same tally whether or not the disc
-//! corpus was exercised** — see issue #16. Measured: the disc suites ran on a
-//! developer desktop (1 936 s, `mesh_consistency_disc` alone 1 220 s) and
-//! skipped on CI (2.4 s total), and *both* reported `207 passed / 0 failed /
-//! 14 ignored` across 30 suites.
+//! corpus was exercised** — issue #16. Measured on `main` @ `4ca0b8e`: this
+//! desktop ran the disc suites (`mesh_consistency_disc` alone **1 215 s**) and
+//! CI skipped them (2.4 s total), and *both* reported
+//! `209 passed / 0 failed / 14 ignored` across 31 suites.
 //!
-//! Two mechanisms compound, and either alone would be survivable:
+//! Two mechanisms compound:
 //!
-//! 1. **A skip is a passing test.** The disc suites do `eprintln!("SKIP: …")`
-//!    and return early from a test that still passes, so a skipped suite and a
-//!    fully exercised one both score `1 passed`. The totals are invariant.
-//! 2. **The message is invisible.** `cargo test` captures a *passing* test's
-//!    output, so neither log contains a `SKIP:` line. The absence of one proves
-//!    nothing, which makes the obvious check useless too.
+//! 1. **A skip is a passing test.** The gated suites print `SKIP:` and return
+//!    early from a test that still passes, so a skipped suite and a fully
+//!    exercised one both score `1 passed`.
+//! 2. **The message is invisible.** `cargo test` captures a passing test's
+//!    output, so neither log contains a `SKIP:` line.
 //!
 //! And `14 ignored` cannot help: `#[ignore]` is static, so that column is the
 //! literal count of attributes in the source and cannot move at runtime.
 //!
-//! This test is the fix for the *report*, not for the control. It always runs,
-//! never fails, and records what was actually available — to a file, because a
-//! passing test's stdout is captured and would be invisible in exactly the CI
-//! log that needs it.
+//! This test fixes the *report*. `tests/common/mod.rs` fixes the *control*.
 
 use std::fmt::Write as _;
 use std::io::Write as _;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
-/// Resolution mirrors the per-suite helpers exactly. If one of those changes,
-/// this drifts — which is itself an argument for the shared helper in #16's
-/// remedy (3).
-fn resolve(
-    env: &str,
-    fallback: &str,
-    want_dir_child: Option<&str>,
-    want_file: bool,
-) -> (String, Option<PathBuf>) {
-    let ok = |p: &Path| -> bool {
-        match (want_dir_child, want_file) {
-            (Some(child), _) => p.join(child).is_dir(),
-            (None, true) => p.is_file(),
-            (None, false) => p.is_dir(),
-        }
-    };
-    if let Ok(v) = std::env::var(env) {
-        let p = PathBuf::from(&v);
-        if ok(&p) {
-            return (format!("PRESENT via ${env}"), Some(p));
-        }
-        return (format!("${env} is set but does not resolve: {v}"), None);
-    }
-    let p = PathBuf::from(fallback);
-    if ok(&p) {
-        // The important case. ${env} is unset, yet the corpus resolved anyway,
-        // so the suites run because of this machine's directory layout — a
-        // property invisible in the command and in the output.
-        return (
-            format!("PRESENT via the HARDCODED fallback, NOT ${env}"),
-            Some(p),
-        );
-    }
-    (
-        "ABSENT — the gated suites will self-skip and still count as passed".into(),
-        None,
-    )
-}
+mod common;
 
-fn target_dir() -> Option<PathBuf> {
-    let exe = std::env::current_exe().ok()?;
-    exe.ancestors()
-        .find(|a| a.file_name().is_some_and(|n| n == "target"))
-        .map(PathBuf::from)
+/// Describe one corpus. Resolution is delegated to `common`, so this cannot
+/// drift from what the suites themselves do — the previous version duplicated
+/// the resolution logic and said so in its own comments.
+fn status(var: &str, resolved: Option<PathBuf>) -> (String, Option<PathBuf>) {
+    match (std::env::var(var), resolved) {
+        (Ok(_), Some(p)) => (format!("PRESENT via ${var}"), Some(p)),
+        // Set but unusable is NOT the same as absent, and wants a different
+        // fix: a typo or a moved directory rather than a machine without the
+        // corpus. Reporting them alike would send someone hunting the wrong one.
+        (Ok(v), None) => (format!("${var} is set but does not resolve: {v}"), None),
+        (Err(_), _) => (
+            format!("ABSENT — ${var} unset; its suites self-skip and still count as passed"),
+            None,
+        ),
+    }
 }
 
 #[test]
 fn corpus_report() {
-    let corpora = [
-        ("SYLPHEED_DISC", "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)", Some("dat"), false),
-        ("SYLPHEED_RES3D", "/home/fabi/RE - Project Sylpheed/sylph_extract/hidden/resource3d", None, false),
-        ("SYLPHEED_ISO", "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja).iso", None, true),
+    let rows = [
+        status("SYLPHEED_DISC", common::disc_root()),
+        status("SYLPHEED_RES3D", common::res3d_dir()),
+        status("SYLPHEED_ISO", common::iso_path()),
     ];
 
     let mut out = String::from("test corpus report (issue #16)\n");
     let mut any = false;
-    for (env, fallback, child, file) in corpora {
-        let (status, path) = resolve(env, fallback, child, file);
+    for (text, path) in &rows {
         any |= path.is_some();
-        let _ = writeln!(out, "  {env:<15} {status}");
+        let _ = writeln!(out, "  {text}");
         if let Some(p) = path {
-            let _ = writeln!(out, "  {:<15}   -> {}", "", p.display());
+            let _ = writeln!(out, "      -> {}", p.display());
         }
     }
     let _ = writeln!(
@@ -107,15 +75,14 @@ fn corpus_report() {
         );
     }
 
-    // Captured for a passing test, so it is only visible with --show-output or
-    // --nocapture. Kept anyway: it is the natural place to look locally.
+    // Captured for a passing test, so visible only with --show-output. Kept
+    // because it is the natural place to look locally.
     println!("{out}");
 
     // The channel that survives capture, and the one CI reads.
     if let Some(dir) = target_dir() {
         let _ = std::fs::write(dir.join("sylpheed-corpus-report.txt"), &out);
     }
-    // Gitea and GitHub both honour this; it puts the block in the run summary.
     if let Ok(p) = std::env::var("GITHUB_STEP_SUMMARY") {
         if let Ok(mut f) = std::fs::OpenOptions::new()
             .create(true)
@@ -127,31 +94,30 @@ fn corpus_report() {
     }
 }
 
-/// The ABSENT branch is the one CI takes, and it cannot be reached on a machine
-/// that has the corpora — so it is exercised directly here rather than shipped
-/// unrun. Same for the "set but does not resolve" branch, which is what a typo
-/// in the env var produces.
-#[test]
-fn resolve_renders_every_branch() {
-    let missing = "/nonexistent/sylpheed/corpus";
-
-    // env unset + fallback missing -> ABSENT
-    std::env::remove_var("SYLPHEED_TEST_PROBE");
-    let (status, path) = resolve("SYLPHEED_TEST_PROBE", missing, None, false);
-    assert!(status.starts_with("ABSENT"), "{status}");
-    assert!(path.is_none());
-
-    // env set to something that does not resolve -> named as such, NOT absent,
-    // because those two states want different fixes.
-    std::env::set_var("SYLPHEED_TEST_PROBE", missing);
-    let (status, path) = resolve("SYLPHEED_TEST_PROBE", missing, None, false);
-    assert!(status.contains("is set but does not resolve"), "{status}");
-    assert!(path.is_none());
-
-    // env set and valid -> attributed to the env var, not the fallback
-    std::env::set_var("SYLPHEED_TEST_PROBE", env!("CARGO_MANIFEST_DIR"));
-    let (status, path) = resolve("SYLPHEED_TEST_PROBE", missing, None, false);
-    assert_eq!(status, "PRESENT via $SYLPHEED_TEST_PROBE");
-    assert!(path.is_some());
-    std::env::remove_var("SYLPHEED_TEST_PROBE");
+fn target_dir() -> Option<PathBuf> {
+    let exe = std::env::current_exe().ok()?;
+    exe.ancestors()
+        .find(|a| a.file_name().is_some_and(|n| n == "target"))
+        .map(PathBuf::from)
+}
+
+/// The three states must render distinctly, and CI only ever exercises one of
+/// them — so they are driven directly here rather than shipped unrun.
+#[test]
+fn status_renders_every_state() {
+    let probe = "SYLPHEED_TEST_PROBE";
+    std::env::remove_var(probe);
+    let (text, path) = status(probe, None);
+    assert!(text.starts_with("ABSENT"), "{text}");
+    assert!(path.is_none());
+
+    std::env::set_var(probe, "/nonexistent/sylpheed/corpus");
+    let (text, _) = status(probe, None);
+    assert!(text.contains("is set but does not resolve"), "{text}");
+
+    std::env::set_var(probe, env!("CARGO_MANIFEST_DIR"));
+    let (text, path) = status(probe, Some(PathBuf::from(env!("CARGO_MANIFEST_DIR"))));
+    assert_eq!(text, format!("PRESENT via ${probe}"));
+    assert!(path.is_some());
+    std::env::remove_var(probe);
 }
diff --git a/crates/sylpheed-formats/tests/idxd_records_disc.rs b/crates/sylpheed-formats/tests/idxd_records_disc.rs
index 3c84e01d..48bf42d8 100644
--- a/crates/sylpheed-formats/tests/idxd_records_disc.rs
+++ b/crates/sylpheed-formats/tests/idxd_records_disc.rs
@@ -13,27 +13,8 @@ use std::path::{Path, PathBuf};
 use sylpheed_formats::hash::tag_hash;
 use sylpheed_formats::{IdxdObject, PakArchive};
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    default.join("dat").is_dir().then(|| default.to_path_buf())
-}
-
-macro_rules! skip_without_disc {
-    ($root:ident) => {
-        let Some($root) = disc_root() else {
-            eprintln!("SKIP: extracted disc not found (set SYLPHEED_DISC to enable)");
-            return;
-        };
-    };
-}
+mod common;
+use common::skip_without_disc;
 
 /// Every `.pak` on the disc, recursively.
 ///
diff --git a/crates/sylpheed-formats/tests/ixud_records_disc.rs b/crates/sylpheed-formats/tests/ixud_records_disc.rs
index c833ad57..bd465dc4 100644
--- a/crates/sylpheed-formats/tests/ixud_records_disc.rs
+++ b/crates/sylpheed-formats/tests/ixud_records_disc.rs
@@ -8,27 +8,8 @@ use std::path::{Path, PathBuf};
 use sylpheed_formats::hash::ixud_hash_str;
 use sylpheed_formats::{IxudObject, PakArchive};
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let d = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    d.join("dat").is_dir().then(|| d.to_path_buf())
-}
-
-macro_rules! skip_without_disc {
-    ($root:ident) => {
-        let Some($root) = disc_root() else {
-            eprintln!("SKIP: set SYLPHEED_DISC");
-            return;
-        };
-    };
-}
+mod common;
+use common::skip_without_disc;
 
 fn all_paks(root: &Path) -> Vec<PathBuf> {
     let mut out = Vec::new();
diff --git a/crates/sylpheed-formats/tests/mesh_consistency_disc.rs b/crates/sylpheed-formats/tests/mesh_consistency_disc.rs
index cc0b73a4..0e6a4ea0 100644
--- a/crates/sylpheed-formats/tests/mesh_consistency_disc.rs
+++ b/crates/sylpheed-formats/tests/mesh_consistency_disc.rs
@@ -11,25 +11,12 @@
 //! rather than as a snapshot of the bug.
 
 use std::collections::BTreeMap;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
 use sylpheed_formats::mesh::Xbg7Model;
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    if default.join("dat").is_dir() {
-        return Some(default.to_path_buf());
-    }
-    None
-}
+mod common;
+use common::disc_root;
 
 /// Rounded (w, h, d) of a model's own geometry.
 fn span(m: &Xbg7Model) -> Option<[i64; 3]> {
diff --git a/crates/sylpheed-formats/tests/mesh_disc.rs b/crates/sylpheed-formats/tests/mesh_disc.rs
index ea4ec8df..19d1aa72 100644
--- a/crates/sylpheed-formats/tests/mesh_disc.rs
+++ b/crates/sylpheed-formats/tests/mesh_disc.rs
@@ -9,16 +9,8 @@
 use std::path::PathBuf;
 use sylpheed_formats::mesh::{material_groups, node_transforms, submesh_albedos, Xbg7Model};
 
-fn res3d_dir() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_RES3D") {
-        let p = PathBuf::from(p);
-        if p.is_dir() {
-            return Some(p);
-        }
-    }
-    let default = PathBuf::from("/home/fabi/RE - Project Sylpheed/sylph_extract/hidden/resource3d");
-    default.is_dir().then_some(default)
-}
+mod common;
+use common::res3d_dir;
 
 #[test]
 #[ignore = "requires extracted disc models — set SYLPHEED_RES3D"]
@@ -378,10 +370,11 @@ fn hero_ship_grouped_pool_decodes() {
 #[ignore]
 fn stage_models_decode() {
     use sylpheed_formats::mesh::Xbg7Model;
-    let dir = std::env::var("SYLPHEED_RES3D").unwrap_or_else(|_| {
-        "/home/fabi/RE - Project Sylpheed/sylph_extract/hidden/resource3d".to_string()
-    });
-    let path = format!("{dir}/Stage_S10.xpr");
+    let Some(dir) = res3d_dir() else {
+        eprintln!("SKIP: set SYLPHEED_RES3D to the extracted resource3d directory");
+        return;
+    };
+    let path = format!("{}/Stage_S10.xpr", dir.display());
     let bytes = std::fs::read(&path).expect("read Stage_S10");
     let models = Xbg7Model::stage_models(&bytes);
     for m in &models {
@@ -423,9 +416,10 @@ fn stage_models_decode() {
 fn stage_models_sweep() {
     use std::time::Instant;
     use sylpheed_formats::mesh::Xbg7Model;
-    let dir = std::env::var("SYLPHEED_RES3D").unwrap_or_else(|_| {
-        "/home/fabi/RE - Project Sylpheed/sylph_extract/hidden/resource3d".to_string()
-    });
+    let Some(dir) = res3d_dir() else {
+        eprintln!("SKIP: set SYLPHEED_RES3D to the extracted resource3d directory");
+        return;
+    };
     let mut names: Vec<_> = std::fs::read_dir(&dir)
         .unwrap()
         .filter_map(|e| e.ok().map(|e| e.file_name().into_string().unwrap()))
@@ -434,7 +428,7 @@ fn stage_models_sweep() {
     names.sort();
     let mut tot = 0usize;
     for n in &names {
-        let bytes = std::fs::read(format!("{dir}/{n}")).unwrap();
+        let bytes = std::fs::read(format!("{}/{n}", dir.display())).unwrap();
         let t0 = Instant::now();
         let models = Xbg7Model::stage_models(&bytes);
         let dt = t0.elapsed().as_millis();
@@ -455,10 +449,11 @@ fn stage_models_sweep() {
 #[ignore]
 fn stage_models_quality_audit() {
     use sylpheed_formats::mesh::Xbg7Model;
-    let dir = std::env::var("SYLPHEED_RES3D").unwrap_or_else(|_| {
-        "/home/fabi/RE - Project Sylpheed/sylph_extract/hidden/resource3d".to_string()
-    });
-    let bytes = std::fs::read(format!("{dir}/Stage_S07.xpr")).unwrap();
+    let Some(dir) = res3d_dir() else {
+        eprintln!("SKIP: set SYLPHEED_RES3D to the extracted resource3d directory");
+        return;
+    };
+    let bytes = std::fs::read(format!("{}/Stage_S07.xpr", dir.display())).unwrap();
     let models = Xbg7Model::stage_models(&bytes);
     let (mut small, mut mid, mut huge, mut dupnames) = (0, 0, 0, 0);
     let mut seen = std::collections::HashSet::new();
diff --git a/crates/sylpheed-formats/tests/movie_manifest_disc.rs b/crates/sylpheed-formats/tests/movie_manifest_disc.rs
index bdea2406..36d03a68 100644
--- a/crates/sylpheed-formats/tests/movie_manifest_disc.rs
+++ b/crates/sylpheed-formats/tests/movie_manifest_disc.rs
@@ -7,10 +7,8 @@ use sylpheed_formats::movie_manifest;
 use sylpheed_formats::slb::VoiceLang;
 use sylpheed_formats::PakArchive;
 
-fn disc_root() -> Option<PathBuf> {
-    let p = PathBuf::from(std::env::var("SYLPHEED_DISC").ok()?);
-    p.join("dat").is_dir().then_some(p)
-}
+mod common;
+use common::disc_root;
 
 /// Read the manifest + `eng\sounds.tbl` out of `tables.pak`.
 fn load_manifest_and_sounds(root: &PathBuf) -> (Vec<u8>, Vec<u8>) {
diff --git a/crates/sylpheed-formats/tests/movie_subtitle_disc.rs b/crates/sylpheed-formats/tests/movie_subtitle_disc.rs
index 760874f5..6b0640c6 100644
--- a/crates/sylpheed-formats/tests/movie_subtitle_disc.rs
+++ b/crates/sylpheed-formats/tests/movie_subtitle_disc.rs
@@ -1,15 +1,11 @@
 //! Real-disc test for the movie subtitle chain. Skipped when the extracted disc
 //! is absent (set `SYLPHEED_DISC` to the extract root to enable).
 
-use std::path::PathBuf;
-
 use sylpheed_formats::movie_subtitle::{self, SubLang};
 use sylpheed_formats::PakArchive;
 
-fn disc_root() -> Option<PathBuf> {
-    let p = PathBuf::from(std::env::var("SYLPHEED_DISC").ok()?);
-    p.join("dat").is_dir().then_some(p)
-}
+mod common;
+use common::disc_root;
 
 #[test]
 fn resolves_english_radio_subtitles() {
diff --git a/crates/sylpheed-formats/tests/pak_idxd_disc.rs b/crates/sylpheed-formats/tests/pak_idxd_disc.rs
index b7e14d61..d433d51f 100644
--- a/crates/sylpheed-formats/tests/pak_idxd_disc.rs
+++ b/crates/sylpheed-formats/tests/pak_idxd_disc.rs
@@ -1,40 +1,16 @@
 //! Integration tests against the real extracted Project Sylpheed disc.
 //!
 //! These are **skipped** (pass as no-ops) when the extracted disc is not present,
-//! so the suite still runs on machines/CI without the game. Point at the disc via
-//! the `SYLPHEED_DISC` env var, or drop it at the default dev path below.
-
-use std::path::{Path, PathBuf};
+//! so the suite still runs on machines/CI without the game. Point at the disc
+//! with the `SYLPHEED_DISC` env var; there is no path fallback (see #16).
 
 use sylpheed_formats::texture::X360Texture;
 use sylpheed_formats::{IdxdObject, PakArchive};
 
+mod common;
+use common::skip_without_disc;
+
 /// Locate the extracted disc root, or `None` to skip.
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    if default.join("dat").is_dir() {
-        return Some(default.to_path_buf());
-    }
-    None
-}
-
-macro_rules! skip_without_disc {
-    ($root:ident) => {
-        let Some($root) = disc_root() else {
-            eprintln!("SKIP: extracted disc not found (set SYLPHEED_DISC to enable)");
-            return;
-        };
-    };
-}
-
 #[test]
 fn deftables_header_and_first_entry() {
     skip_without_disc!(root);
diff --git a/crates/sylpheed-formats/tests/slb_disc.rs b/crates/sylpheed-formats/tests/slb_disc.rs
index e17b4e56..c584335b 100644
--- a/crates/sylpheed-formats/tests/slb_disc.rs
+++ b/crates/sylpheed-formats/tests/slb_disc.rs
@@ -9,10 +9,8 @@ use sylpheed_formats::hash::name_hash;
 use sylpheed_formats::slb::{self, VoiceLang};
 use sylpheed_formats::PakArchive;
 
-fn disc_root() -> Option<PathBuf> {
-    let p = PathBuf::from(std::env::var("SYLPHEED_DISC").ok()?);
-    p.join("dat").is_dir().then_some(p)
-}
+mod common;
+use common::disc_root;
 
 /// Read `[off, off+size)` from `dat/sound.p00..` (segments concatenated).
 fn read_range(root: &PathBuf, mut off: u64, size: usize) -> Vec<u8> {
diff --git a/crates/sylpheed-formats/tests/slb_leading_segment_disc.rs b/crates/sylpheed-formats/tests/slb_leading_segment_disc.rs
index c5e69f6b..a9204206 100644
--- a/crates/sylpheed-formats/tests/slb_leading_segment_disc.rs
+++ b/crates/sylpheed-formats/tests/slb_leading_segment_disc.rs
@@ -5,31 +5,12 @@
 //! `RIFF`. The banks that looked fine were the ones whose leading segment is
 //! silence. One rule, two outcomes.
 
-use std::path::{Path, PathBuf};
+use std::path::Path;
 
 use sylpheed_formats::{slb, PakArchive};
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    default.join("dat").is_dir().then(|| default.to_path_buf())
-}
-
-macro_rules! skip_without_disc {
-    ($root:ident) => {
-        let Some($root) = disc_root() else {
-            eprintln!("SKIP: set SYLPHEED_DISC");
-            return;
-        };
-    };
-}
+mod common;
+use common::skip_without_disc;
 
 fn bank(root: &Path, n: u32) -> Vec<u8> {
     let snd = PakArchive::open(root.join("dat/sound.pak")).expect("sound.pak");
diff --git a/crates/sylpheed-formats/tests/texture_disc.rs b/crates/sylpheed-formats/tests/texture_disc.rs
index 6e552ae9..0c8525ac 100644
--- a/crates/sylpheed-formats/tests/texture_disc.rs
+++ b/crates/sylpheed-formats/tests/texture_disc.rs
@@ -1,28 +1,15 @@
 //! Integration test: run the XPR2 texture pipeline against REAL `.xpr` files
 //! read directly from the retail disc image, reproducing exactly what the
 //! viewer's texture-preview path does (`identify_format` → `X360Texture::
-//! from_xpr2`). Skipped unless `SYLPHEED_ISO` points at the disc (or the
-//! default dev path exists).
+//! from_xpr2`). Skipped unless `SYLPHEED_ISO` points at the disc image.
 //!
 //! Run: `cargo test -p sylpheed-formats --test texture_disc -- --ignored --nocapture`
 
-use std::path::PathBuf;
-
 use sylpheed_formats::texture::X360Texture;
 use sylpheed_formats::vfs::identify_format;
 
-fn iso_path() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_ISO") {
-        let p = PathBuf::from(p);
-        if p.is_file() {
-            return Some(p);
-        }
-    }
-    let default = PathBuf::from(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja).iso",
-    );
-    default.is_file().then_some(default)
-}
+mod common;
+use common::iso_path;
 
 #[tokio::test]
 #[ignore = "requires the retail ISO — set SYLPHEED_ISO"]
diff --git a/crates/sylpheed-formats/tests/ui_focus_kind_disc.rs b/crates/sylpheed-formats/tests/ui_focus_kind_disc.rs
index b2498463..2ef79795 100644
--- a/crates/sylpheed-formats/tests/ui_focus_kind_disc.rs
+++ b/crates/sylpheed-formats/tests/ui_focus_kind_disc.rs
@@ -17,25 +17,12 @@ use std::path::{Path, PathBuf};
 
 use sylpheed_formats::{pak::PakArchive, ratc, ui_layout};
 
+mod common;
+use common::disc_root;
+
 const DECL_TABLE_AT: usize = 0x20;
 const DECL_ENTRY: usize = 60;
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    if default.join("dat").is_dir() {
-        return Some(default.to_path_buf());
-    }
-    None
-}
-
 fn for_each_build(root: &Path, mut f: impl FnMut(&str, &[u8])) {
     let mut paks: Vec<PathBuf> = std::fs::read_dir(root.join("dat"))
         .expect("dat/")
diff --git a/crates/sylpheed-formats/tests/ui_header_time_disc.rs b/crates/sylpheed-formats/tests/ui_header_time_disc.rs
index d9eb8e0b..3d7e7c65 100644
--- a/crates/sylpheed-formats/tests/ui_header_time_disc.rs
+++ b/crates/sylpheed-formats/tests/ui_header_time_disc.rs
@@ -16,21 +16,8 @@ use std::path::{Path, PathBuf};
 
 use sylpheed_formats::{pak::PakArchive, ratc, ui_layout};
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    if default.join("dat").is_dir() {
-        return Some(default.to_path_buf());
-    }
-    None
-}
+mod common;
+use common::disc_root;
 
 fn for_each_build(root: &Path, mut f: impl FnMut(&str, &[u8])) {
     let mut paks: Vec<PathBuf> = std::fs::read_dir(root.join("dat"))
diff --git a/crates/sylpheed-formats/tests/ui_opt_link_disc.rs b/crates/sylpheed-formats/tests/ui_opt_link_disc.rs
index d1c54833..2dcd0d1b 100644
--- a/crates/sylpheed-formats/tests/ui_opt_link_disc.rs
+++ b/crates/sylpheed-formats/tests/ui_opt_link_disc.rs
@@ -17,21 +17,8 @@ use std::path::{Path, PathBuf};
 
 use sylpheed_formats::{pak::PakArchive, ratc, ui_layout};
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    if default.join("dat").is_dir() {
-        return Some(default.to_path_buf());
-    }
-    None
-}
+mod common;
+use common::disc_root;
 
 fn for_each_build(root: &Path, mut f: impl FnMut(&str, &[u8])) {
     let mut paks: Vec<PathBuf> = std::fs::read_dir(root.join("dat"))
diff --git a/crates/sylpheed-formats/tests/ui_paint_order_disc.rs b/crates/sylpheed-formats/tests/ui_paint_order_disc.rs
index 7f280a32..2804792b 100644
--- a/crates/sylpheed-formats/tests/ui_paint_order_disc.rs
+++ b/crates/sylpheed-formats/tests/ui_paint_order_disc.rs
@@ -21,30 +21,8 @@ use sylpheed_formats::{
     ui_layout::{self, ComposeOptions},
 };
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    if default.join("dat").is_dir() {
-        return Some(default.to_path_buf());
-    }
-    None
-}
-
-macro_rules! skip_without_disc {
-    ($root:ident) => {
-        let Some($root) = disc_root() else {
-            eprintln!("SKIP: extracted disc not found (set SYLPHEED_DISC to enable)");
-            return;
-        };
-    };
-}
+mod common;
+use common::skip_without_disc;
 
 /// Every parseable screen build on the disc, as (pak name, bundle bytes).
 fn builds(root: &Path) -> Vec<(String, Vec<u8>)> {
diff --git a/crates/sylpheed-formats/tests/ui_prm_primitives_disc.rs b/crates/sylpheed-formats/tests/ui_prm_primitives_disc.rs
index 9b8e4357..6e3e0198 100644
--- a/crates/sylpheed-formats/tests/ui_prm_primitives_disc.rs
+++ b/crates/sylpheed-formats/tests/ui_prm_primitives_disc.rs
@@ -9,21 +9,8 @@ use std::path::{Path, PathBuf};
 
 use sylpheed_formats::{pak::PakArchive, ratc, ui_layout};
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    if default.join("dat").is_dir() {
-        return Some(default.to_path_buf());
-    }
-    None
-}
+mod common;
+use common::disc_root;
 
 fn for_each_build(root: &Path, mut f: impl FnMut(&str, &[u8])) {
     let mut paks: Vec<PathBuf> = std::fs::read_dir(root.join("dat"))
diff --git a/crates/sylpheed-formats/tests/ui_screen_vs_fragment_disc.rs b/crates/sylpheed-formats/tests/ui_screen_vs_fragment_disc.rs
index 9e8bcec7..f2d63c37 100644
--- a/crates/sylpheed-formats/tests/ui_screen_vs_fragment_disc.rs
+++ b/crates/sylpheed-formats/tests/ui_screen_vs_fragment_disc.rs
@@ -21,21 +21,8 @@ use std::path::{Path, PathBuf};
 
 use sylpheed_formats::{pak::PakArchive, ratc, ui_layout};
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    if default.join("dat").is_dir() {
-        return Some(default.to_path_buf());
-    }
-    None
-}
+mod common;
+use common::disc_root;
 
 fn for_each_build(root: &Path, mut f: impl FnMut(&str, &[u8])) {
     let mut paks: Vec<PathBuf> = std::fs::read_dir(root.join("dat"))
diff --git a/crates/sylpheed-formats/tests/ui_surfaces_disc.rs b/crates/sylpheed-formats/tests/ui_surfaces_disc.rs
index 5acb1e5f..fdd1a024 100644
--- a/crates/sylpheed-formats/tests/ui_surfaces_disc.rs
+++ b/crates/sylpheed-formats/tests/ui_surfaces_disc.rs
@@ -10,30 +10,8 @@ use std::path::{Path, PathBuf};
 
 use sylpheed_formats::{lsta, pak::PakArchive, ratc, t8ad};
 
-fn disc_root() -> Option<PathBuf> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        let p = PathBuf::from(p);
-        if p.join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let default = Path::new(
-        "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)",
-    );
-    if default.join("dat").is_dir() {
-        return Some(default.to_path_buf());
-    }
-    None
-}
-
-macro_rules! skip_without_disc {
-    ($root:ident) => {
-        let Some($root) = disc_root() else {
-            eprintln!("SKIP: extracted disc not found (set SYLPHEED_DISC to enable)");
-            return;
-        };
-    };
-}
+mod common;
+use common::skip_without_disc;
 
 /// Every entry of every pak, plus every RATC child, as raw bytes.
 fn for_each_blob(root: &Path, mut f: impl FnMut(&str, &str, &[u8])) {
diff --git a/crates/sylpheed-formats/tests/unit_layout_disc.rs b/crates/sylpheed-formats/tests/unit_layout_disc.rs
index 40012e83..575c2a1e 100644
--- a/crates/sylpheed-formats/tests/unit_layout_disc.rs
+++ b/crates/sylpheed-formats/tests/unit_layout_disc.rs
@@ -11,6 +11,9 @@ use sylpheed_formats::idxd::IdxdObject;
 use sylpheed_formats::pak::PakArchive;
 use sylpheed_formats::unit_layout::{fields, Kind};
 
+mod common;
+use common::disc_root;
+
 /// Live objects identified in the dump, with the disc record each one is.
 /// `bf001` is here because full-record agreement is what identified it: the
 /// four-value signature also fitted `UN_be005_ADAN_SpaceFortress`, which
@@ -31,19 +34,6 @@ const IDENTIFIED: &[(&str, &str)] = &[
 
 const DUMP: &str = include_str!("../../../docs/re/captures/stage02-live-unit-definitions-deep.txt");
 
-fn disc_root() -> Option<String> {
-    if let Ok(p) = std::env::var("SYLPHEED_DISC") {
-        if std::path::Path::new(&p).join("dat").is_dir() {
-            return Some(p);
-        }
-    }
-    let d = "/home/fabi/RE - Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja)";
-    std::path::Path::new(d)
-        .join("dat")
-        .is_dir()
-        .then(|| d.to_string())
-}
-
 /// `va -> offset -> value`, from the dump's `addr +off hex u32 f32` columns.
 fn live() -> BTreeMap<String, BTreeMap<usize, f32>> {
     let mut out: BTreeMap<String, BTreeMap<usize, f32>> = BTreeMap::new();
@@ -70,7 +60,8 @@ fn mapped_fields_match_the_disc_records() {
         eprintln!("SKIP: extracted disc not found (set SYLPHEED_DISC to enable)");
         return;
     };
-    let pak = PakArchive::open(format!("{disc}/dat/GP_MAIN_GAME_E.pak")).expect("main pak");
+    let pak =
+        PakArchive::open(format!("{}/dat/GP_MAIN_GAME_E.pak", disc.display())).expect("main pak");
     let live = live();
     let floats: Vec<_> = fields()
         .into_iter()
diff --git a/justfile b/justfile
index c79d5829..4034b45f 100644
--- a/justfile
+++ b/justfile
@@ -71,6 +71,28 @@ sniff-unknown:
 test:
     cargo test --workspace
 
+# Run the disc-backed suites. They are gated on the environment ALONE now (#16):
+# no source file hardcodes a path any more, so nothing runs by accident because
+# a machine happens to have a directory. Put your paths in `.env` (already
+# gitignored as a local dev override):
+#
+#   SYLPHEED_DISC="/path/to/extracted/disc"    # the dir containing dat/
+#
+# QUOTE the values. These paths contain spaces, and an unquoted `VAR=a b c`
+# is parsed as "run command b with VAR=a" -- it fails silently into ABSENT.
+#   SYLPHEED_RES3D=/path/to/hidden/resource3d
+#   SYLPHEED_ISO=/path/to/game.iso
+#
+# Read the corpus block the run prints -- the pass/fail tally is identical
+# whether or not the corpus was exercised, which is the whole of #16.
+test-disc:
+    #!/usr/bin/env bash
+    set -euo pipefail
+    [ -f .env ] && set -a && . ./.env && set +a
+    cargo test --workspace
+    echo "--- corpus report ---"
+    cat target/sylpheed-corpus-report.txt
+
 # Run tests including ISO integration tests (requires SYLPHEED_ISO env var)
 test-integration:
     SYLPHEED_ISO=./game.iso cargo test --workspace -- --include-ignored