OrcaSlicer/tests/libslic3r/test_imex_helpers.cpp

#include <catch2/catch_all.hpp>

#include "libslic3r/IMEXHelpers.hpp"
#include "libslic3r/PrintConfig.hpp"
#include "libslic3r/Point.hpp"

using namespace Slic3r;
using Catch::Matchers::WithinAbs;

static ConfigOptionInts make_pem(std::vector<int> v) {
    ConfigOptionInts o;
    o.values = std::move(v);
    return o;
}

TEST_CASE("effective_physical_extruder_map — explicit wins", "[IMEX]") {
    auto explicit_pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    auto pei          = make_pem({1, 2, 3, 4}); // would derive to {0,1,2,3}
    auto out = effective_physical_extruder_map(&explicit_pem, &pei);
    REQUIRE(out.values == std::vector<int>{0, 0, 0, 0, 1, 2, 3});
}

TEST_CASE("effective_physical_extruder_map — default pem falls back to pei derive", "[IMEX]") {
    auto default_pem = make_pem({0});           // size 1, the PrintConfig default
    auto pei         = make_pem({1, 2});        // 1-indexed IDEX
    auto out = effective_physical_extruder_map(&default_pem, &pei);
    REQUIRE(out.values == std::vector<int>{0, 1}); // 1-indexed → 0-indexed
}

TEST_CASE("effective_physical_extruder_map — null explicit, pei present", "[IMEX]") {
    auto pei = make_pem({1, 2, 3});
    auto out = effective_physical_extruder_map(nullptr, &pei);
    REQUIRE(out.values == std::vector<int>{0, 1, 2});
}

TEST_CASE("effective_physical_extruder_map — both absent yields empty", "[IMEX]") {
    auto out = effective_physical_extruder_map(nullptr, nullptr);
    REQUIRE(out.values.empty());
}

TEST_CASE("effective_physical_extruder_map — IDEX ghost-color regression guard", "[IMEX]") {
    // Printer with printer_extruder_id = [1, 2] and no explicit pem (default {0}).
    // Before the GUI fix, this scenario produced a black ghost on T1 because
    // first_filament_for_physical_head({0}, 1) == -1.
    auto default_pem = make_pem({0});
    auto pei         = make_pem({1, 2});
    auto pem         = effective_physical_extruder_map(&default_pem, &pei);
    REQUIRE(first_filament_for_physical_head(pem, 0) == 0);
    REQUIRE(first_filament_for_physical_head(pem, 1) == 1); // no longer -1
}

TEST_CASE("imex_pem_tool_for — non-parallel mode returns -1", "[IMEX]") {
    // Empty mode string (not in IMEX) and "primary" (IMEX present but not parallel) both
    // short-circuit to bare-firmware PA/temp emission.
    auto pem = make_pem({0, 1, 2});
    REQUIRE(imex_pem_tool_for(0, "",        pem) == -1);
    REQUIRE(imex_pem_tool_for(1, "primary", pem) == -1);
    REQUIRE(imex_pem_tool_for(2, "primary", pem) == -1);
}

TEST_CASE("imex_pem_tool_for — parallel mode with empty pem returns -1", "[IMEX]") {
    // Defense-in-depth for exotic profiles where pem never gets populated. get_at would
    // throw on an empty pem; the helper must return -1 instead so the writer emits bare.
    ConfigOptionInts empty_pem;
    REQUIRE(imex_pem_tool_for(0, "copy_mode",   empty_pem) == -1);
    REQUIRE(imex_pem_tool_for(3, "mirror_mode", empty_pem) == -1);
}

TEST_CASE("imex_pem_tool_for — identity pem routes filament to itself", "[IMEX]") {
    // IDEX with printer_extruder_id = [1, 2] auto-derives pem = [0, 1]; non-MMU is identity.
    auto pem = make_pem({0, 1});
    REQUIRE(imex_pem_tool_for(0, "copy_mode", pem) == 0);
    REQUIRE(imex_pem_tool_for(1, "copy_mode", pem) == 1);
}

TEST_CASE("imex_pem_tool_for — MMU collapse routes multiple logical slots to one physical", "[IMEX]") {
    // 7-slot printer: first four slots share physical extruder 0 (a 4-lane MMU),
    // slots 4/5/6 are independent on 1/2/3. Filament index is the logical slot;
    // the helper returns the physical extruder carrying it.
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    REQUIRE(imex_pem_tool_for(0, "copy_mode", pem) == 0);
    REQUIRE(imex_pem_tool_for(3, "copy_mode", pem) == 0); // MMU collapse: T3 logical → T0 physical
    REQUIRE(imex_pem_tool_for(6, "copy_mode", pem) == 3);
}

TEST_CASE("first_filament_for_physical_head — identity pem", "[IMEX]") {
    auto pem = make_pem({0, 1, 2, 3});
    REQUIRE(first_filament_for_physical_head(pem, 0) == 0);
    REQUIRE(first_filament_for_physical_head(pem, 1) == 1);
    REQUIRE(first_filament_for_physical_head(pem, 2) == 2);
    REQUIRE(first_filament_for_physical_head(pem, 3) == 3);
    REQUIRE(first_filament_for_physical_head(pem, 4) == -1);
}

TEST_CASE("first_filament_for_physical_head — AFC routing", "[IMEX]") {
    // User's IQEX: 4 AFC lanes on T0, direct extruders on T1, T2, T3
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    REQUIRE(first_filament_for_physical_head(pem, 0) == 0); // first of T0's lanes
    REQUIRE(first_filament_for_physical_head(pem, 1) == 4);
    REQUIRE(first_filament_for_physical_head(pem, 2) == 5);
    REQUIRE(first_filament_for_physical_head(pem, 3) == 6);
    REQUIRE(first_filament_for_physical_head(pem, 5) == -1); // no head 5
}

TEST_CASE("first_filament_for_physical_head — empty pem", "[IMEX]") {
    ConfigOptionInts pem;
    REQUIRE(first_filament_for_physical_head(pem, 0) == 0);
    REQUIRE(first_filament_for_physical_head(pem, 1) == -1);
}

TEST_CASE("has_mmu — pure IDEX", "[IMEX]") {
    REQUIRE_FALSE(has_mmu(make_pem({0, 1})));
    REQUIRE_FALSE(has_mmu(make_pem({0, 1, 2, 3})));
}

TEST_CASE("has_mmu — MMU on one head", "[IMEX]") {
    REQUIRE(has_mmu(make_pem({0, 0, 0, 0, 1, 2, 3}))); // user's IQEX
    REQUIRE(has_mmu(make_pem({0, 0}))); // tiny MMU
}

TEST_CASE("has_mmu — MMU on second head", "[IMEX]") {
    // Hypothetical future: direct extruder on T0, MMU on T1
    REQUIRE(has_mmu(make_pem({0, 1, 1, 1})));
}

TEST_CASE("has_mmu — empty / single-entry pem", "[IMEX]") {
    REQUIRE_FALSE(has_mmu(make_pem({})));
    REQUIRE_FALSE(has_mmu(make_pem({0})));
}

TEST_CASE("imex_primary_logical_from_objects — AFC primary picks the object's slot", "[IMEX]") {
    // User's Neo XP 0.6: pem maps slots 0-3 to physical 0 (4-lane AFC manifold),
    // slots 4-6 to physicals 1/2/3.  Object assigned to 1-based slot 3 = 0-based 2.
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    REQUIRE(imex_primary_logical_from_objects({3}, pem, 0) == 2);
}

TEST_CASE("imex_primary_logical_from_objects — multi-color AFC primary returns first match", "[IMEX]") {
    // Two objects on the AFC manifold (slots 0 and 2 in 1-based = slots 0 and 2 in
    // 0-based wait that's wrong let me redo).  Two objects: 1-based slots 1 and 3
    // (= 0-based 0 and 2).  Both route to physical 0 via pem.  First in input wins.
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    REQUIRE(imex_primary_logical_from_objects({1, 3}, pem, 0) == 0); // first match
    REQUIRE(imex_primary_logical_from_objects({3, 1}, pem, 0) == 2); // order matters
}

TEST_CASE("imex_primary_logical_from_objects — direct extruder primary unambiguous", "[IMEX]") {
    // Object on 1-based slot 5 = 0-based 4 (direct extruder T1 in the user's layout).
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    REQUIRE(imex_primary_logical_from_objects({5}, pem, 1) == 4);
}

TEST_CASE("imex_primary_logical_from_objects — no object routed to primary returns -1", "[IMEX]") {
    // Object on 1-based slot 5 (= physical 1) but primary_physical is 0.  No object
    // on the plate routes to T0 — caller should fall back / treat as missing.
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    REQUIRE(imex_primary_logical_from_objects({5}, pem, 0) == -1);
}

TEST_CASE("imex_primary_logical_from_objects — empty inputs", "[IMEX]") {
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    REQUIRE(imex_primary_logical_from_objects({}, pem, 0) == -1);  // no objects
    ConfigOptionInts empty_pem;
    REQUIRE(imex_primary_logical_from_objects({1, 3}, empty_pem, 0) == -1); // empty pem
}

TEST_CASE("imex_secondary_logical_slots — copy mode skips primary, falls back to first-routed", "[IMEX]") {
    // User's setup: copy mode active = [0, 1] (T0 primary, T1 copy), no plate map override.
    // Secondary T1 should resolve to first slot whose pem is 1 = slot 4.
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    auto out = imex_secondary_logical_slots({0, 1}, /*primary*/0, /*plate_map*/{}, pem);
    REQUIRE(out == std::vector<int>{4});
}

TEST_CASE("imex_secondary_logical_slots — IQEX 4-mode enumerates all secondaries", "[IMEX]") {
    // iq-copy / iq-mirror: active = [0, 1, 2, 3], primary = 0.
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    auto out = imex_secondary_logical_slots({0, 1, 2, 3}, /*primary*/0, /*plate_map*/{}, pem);
    REQUIRE(out == std::vector<int>{4, 5, 6}); // first slot for each physical 1, 2, 3
}

TEST_CASE("imex_secondary_logical_slots — per-plate override wins for secondary", "[IMEX]") {
    // User picks slot 6 (1-based) for T1 via the IMEX ghost picker.  plate_map[1] = 6.
    // resolve_filament_for_head should subtract 1: 0-based slot 5.
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    std::map<int, int> plate_map{{1, 6}};
    auto out = imex_secondary_logical_slots({0, 1}, /*primary*/0, plate_map, pem);
    REQUIRE(out == std::vector<int>{5});
}

TEST_CASE("imex_secondary_logical_slots — drops unrouted physicals, deduplicates", "[IMEX]") {
    // pem only has 2 entries (slot 0 -> phys 0, slot 1 -> phys 1).  active includes
    // a phys 2 that has no logical → should be dropped.  Also: same pem has both
    // slots routing to the same physical to test dedup.
    auto pem = make_pem({0, 1});
    auto out = imex_secondary_logical_slots({0, 1, 2}, /*primary*/0, {}, pem);
    REQUIRE(out == std::vector<int>{1}); // phys 2 unrouted, primary skipped, only phys 1's slot 1 left

    // Dedup: two physicals resolving to the same logical (via plate_map override).
    std::map<int, int> dup_map{{1, 1}, {2, 1}}; // both T1 and T2 → 1-based slot 1 = 0-based 0
    auto pem2 = make_pem({0, 0, 0});
    auto out2 = imex_secondary_logical_slots({0, 1, 2}, /*primary*/0, dup_map, pem2);
    REQUIRE(out2 == std::vector<int>{0}); // both secondaries point at slot 0; only emitted once
}

TEST_CASE("imex_secondary_logical_slots — only-primary-active returns empty", "[IMEX]") {
    // Primary mode (just T0 active) → no secondaries.
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    auto out = imex_secondary_logical_slots({0}, /*primary*/0, {}, pem);
    REQUIRE(out.empty());
}

TEST_CASE("parse_imex_head_filament_map — round-trip", "[IMEX]") {
    auto m = parse_imex_head_filament_map("0:3,4:5");
    REQUIRE(m.size() == 2);
    REQUIRE(m[0] == 3);
    REQUIRE(m[4] == 5);
}

TEST_CASE("parse_imex_head_filament_map — whitespace + empty tokens", "[IMEX]") {
    auto m = parse_imex_head_filament_map("  0 : 3 , , 4:5  ");
    REQUIRE(m.size() == 2);
    REQUIRE(m[0] == 3);
    REQUIRE(m[4] == 5);
}

TEST_CASE("parse_imex_head_filament_map — empty string", "[IMEX]") {
    REQUIRE(parse_imex_head_filament_map("").empty());
}

TEST_CASE("resolve_filament_for_head — override wins", "[IMEX]") {
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    std::map<int,int> plate_map{{0, 3}}; // 1-based slot 3 = 0-based logical 2
    REQUIRE(resolve_filament_for_head(plate_map, pem, 0) == 2);
}

TEST_CASE("resolve_filament_for_head — fallback when unset", "[IMEX]") {
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    std::map<int,int> plate_map{}; // empty
    REQUIRE(resolve_filament_for_head(plate_map, pem, 0) == 0); // first pem-routed
    REQUIRE(resolve_filament_for_head(plate_map, pem, 1) == 4);
}

TEST_CASE("resolve_filament_for_head — no routing for head", "[IMEX]") {
    auto pem = make_pem({0, 1}); // no head 2
    std::map<int,int> plate_map{};
    REQUIRE(resolve_filament_for_head(plate_map, pem, 2) == -1);
}

TEST_CASE("imex_primary_tool_for_mode — role marker authoritative", "[IMEX]") {
    // Tab.cpp enforces one Primary per mode; position is not semantically meaningful.
    REQUIRE(imex_primary_tool_for_mode("0:P,1:C,2:C") == 0);
    REQUIRE(imex_primary_tool_for_mode("1:C,0:P,2:M") == 0);
    REQUIRE(imex_primary_tool_for_mode("1:C,2:M,3:P") == 3);
}

TEST_CASE("imex_primary_tool_for_mode — backwards-compat plain index", "[IMEX]") {
    REQUIRE(imex_primary_tool_for_mode("0") == 0);
    REQUIRE(imex_primary_tool_for_mode("2") == 2);
    // Bare index wins when no :P marker is present; first bare index takes primary.
    REQUIRE(imex_primary_tool_for_mode("1,2,3") == 1);
}

TEST_CASE("imex_primary_tool_for_mode — explicit :P beats bare index", "[IMEX]") {
    // Mixed serialization: role marker must dominate over bare-index fallback.
    REQUIRE(imex_primary_tool_for_mode("1,2:P,3") == 2);
}

TEST_CASE("imex_primary_tool_for_mode — empty + malformed", "[IMEX]") {
    REQUIRE(imex_primary_tool_for_mode("") == -1);
    REQUIRE(imex_primary_tool_for_mode(",,") == -1);
    REQUIRE(imex_primary_tool_for_mode("abc:P") == -1); // idx not parseable
    REQUIRE(imex_primary_tool_for_mode("-1:P") == -1);   // negative idx rejected
}

TEST_CASE("imex_primary_tool_for_mode — whitespace tolerant", "[IMEX]") {
    REQUIRE(imex_primary_tool_for_mode("  0 : P , 1 : C ") == 0);
}

TEST_CASE("has_non_primary_mmu — MMU on primary only", "[IMEX]") {
    // User's Neo XP 0.6: 4 AFC lanes on T0, singles on T4/T5/T6.
    // Primary = 0 → no other head has MMU.
    auto pem = make_pem({0, 0, 0, 0, 4, 5, 6});
    REQUIRE_FALSE(has_non_primary_mmu(pem, 0));
}

TEST_CASE("has_non_primary_mmu — MMU on secondary", "[IMEX]") {
    // Direct extruder on T0, MMU on T1 → non-primary MMU present.
    auto pem = make_pem({0, 1, 1, 1});
    REQUIRE(has_non_primary_mmu(pem, 0));
}

TEST_CASE("has_non_primary_mmu — pure IDEX", "[IMEX]") {
    REQUIRE_FALSE(has_non_primary_mmu(make_pem({0, 1}), 0));
    REQUIRE_FALSE(has_non_primary_mmu(make_pem({0, 1, 2, 3}), 0));
}

TEST_CASE("has_non_primary_mmu — secondary single-lane", "[IMEX]") {
    // Primary is T4 (single filament); T0 has MMU.
    auto pem = make_pem({0, 0, 0, 0, 4});
    REQUIRE(has_non_primary_mmu(pem, 4));
}

TEST_CASE("has_non_primary_mmu — empty / single-entry pem", "[IMEX]") {
    REQUIRE_FALSE(has_non_primary_mmu(make_pem({}), 0));
    REQUIRE_FALSE(has_non_primary_mmu(make_pem({0}), 0));
}

TEST_CASE("imex_head_transform — copy mode is pure translation", "[IMEX]") {
    const Vec2d offset{120.0, 0.0};
    Transform3d xf = imex_head_transform(0, 1, ImexRole::Copy, offset);
    const Vec3d in{10.0, 20.0, 30.0};
    const Vec3d out = xf * in;
    REQUIRE_THAT(out.x(), WithinAbs(130.0, 1e-9));
    REQUIRE_THAT(out.y(), WithinAbs(20.0,  1e-9));
    REQUIRE_THAT(out.z(), WithinAbs(30.0,  1e-9));
}

TEST_CASE("imex_head_transform — mirror at origin places ghost at gantry offset", "[IMEX]") {
    // Primary instance at origin: ghost origin lands at the gantry offset (Copy-style),
    // and applying mirror flips geometry about origin (= primary's translation).
    const Vec2d offset{120.0, 0.0};
    Transform3d xf = imex_head_transform(0, 1, ImexRole::Mirror, offset);
    const Vec3d mapped = xf * Vec3d::Zero();
    REQUIRE_THAT(mapped.x(), WithinAbs(120.0, 1e-9));
    REQUIRE_THAT(mapped.y(), WithinAbs(0.0,   1e-9));
    REQUIRE_THAT(mapped.z(), WithinAbs(0.0,   1e-9));
}

TEST_CASE("imex_head_transform — mirror lands ghost at reflected position in target zone", "[IMEX]") {
    // User's example: primary zone is 100x100 centered at (50, 50), primary at (80, 20),
    // gantry offset (100, 0) places the mirror zone centered at (150, 50). Ghost origin
    // should land at the reflection of the primary through the zone-boundary plane
    // (x = 100), i.e. world-space (120, 20, 0) — NOT the Copy-style (180, 20, 0).
    const Vec2d offset{100.0, 0.0};
    const Vec2d primary_zone_center{50.0, 50.0};
    Transform3d xf = imex_head_transform(0, 1, ImexRole::Mirror, offset, primary_zone_center);

    const Vec3d primary{80.0, 20.0, 0.0};
    const Vec3d ghost_origin = xf * primary;
    REQUIRE_THAT(ghost_origin.x(), WithinAbs(120.0, 1e-9));
    REQUIRE_THAT(ghost_origin.y(), WithinAbs(20.0,  1e-9));

    // Model point at primary + (+5 X) lands 5 LEFT of ghost origin (geometry still flipped).
    const Vec3d mapped = xf * (primary + Vec3d(5.0, 0.0, 0.0));
    REQUIRE_THAT(mapped.x(), WithinAbs(115.0, 1e-9));
    REQUIRE_THAT(mapped.y(), WithinAbs(20.0,  1e-9));
}

TEST_CASE("imex_head_transform — mirror reflects primary drag motion", "[IMEX]") {
    // Dragging the primary must reflect the ghost across the zone-boundary plane:
    // primary +X → ghost -X (mirrored), primary +Y → ghost +Y (1:1). Without this the
    // ghost stops being a true mirror once the primary moves.
    const Vec2d offset{120.0, 0.0};
    const Vec2d primary_zone_center{60.0, 50.0};
    Transform3d xf = imex_head_transform(0, 1, ImexRole::Mirror, offset, primary_zone_center);

    const Vec3d p0{10.0, 20.0, 0.0};
    const Vec3d p1{40.0, 15.0, 0.0};
    const Vec3d ghost0 = xf * p0;
    const Vec3d ghost1 = xf * p1;
    const Vec3d ghost_delta   = ghost1 - ghost0;
    const Vec3d primary_delta = p1 - p0;

    REQUIRE_THAT(ghost_delta.x(), WithinAbs(-primary_delta.x(), 1e-9)); // X inverted
    REQUIRE_THAT(ghost_delta.y(), WithinAbs( primary_delta.y(), 1e-9)); // Y 1:1
    REQUIRE_THAT(ghost_delta.z(), WithinAbs( primary_delta.z(), 1e-9));
}

TEST_CASE("imex_head_transform — mirror reflects model point across primary origin", "[IMEX]") {
    // Primary at origin, offset +X. Model point at +5 X lands 5 left of ghost origin.
    // Matches the pre-refactor semantics for the special case primary_origin = 0.
    const Vec2d offset{120.0, 0.0};
    Transform3d xf = imex_head_transform(0, 1, ImexRole::Mirror, offset);
    const Vec3d in{5.0, 7.0, 0.0};
    const Vec3d out = xf * in;
    REQUIRE_THAT(out.x(), WithinAbs(115.0, 1e-9));
    REQUIRE_THAT(out.y(), WithinAbs(7.0,   1e-9));
}

TEST_CASE("imex_head_transform — mirror reflection is X-axis regardless of offset direction", "[IMEX]") {
    // Mirror's reflection plane normal is the primary-row gantry axis (X), not
    // gantry_offset.normalized(). A pure-Y offset (off-row target) must still flip
    // X, not Y — otherwise off-row Mirror ghosts end up rotated vs their on-row peers.
    const Vec2d offset{0.0, 80.0};
    Transform3d xf = imex_head_transform(0, 1, ImexRole::Mirror, offset);
    const Vec3d in{3.0, 10.0, 0.0};
    const Vec3d out = xf * in;
    REQUIRE_THAT(out.x(), WithinAbs(-3.0, 1e-9));  // X flipped about origin
    REQUIRE_THAT(out.y(), WithinAbs(90.0, 1e-9));  // Y translated by gantry, unflipped
}

TEST_CASE("imex_head_transform — primary is identity", "[IMEX]") {
    const Vec2d offset{120.0, 30.0};
    Transform3d xf = imex_head_transform(0, 0, ImexRole::Primary, offset);
    REQUIRE(xf.isApprox(Transform3d::Identity()));
}

TEST_CASE("imex_head_transform — mirror with zero offset is identity", "[IMEX]") {
    const Vec2d offset{0.0, 0.0};
    Transform3d xf = imex_head_transform(0, 1, ImexRole::Mirror, offset);
    REQUIRE(xf.isApprox(Transform3d::Identity()));
}

TEST_CASE("imex_head_transform — mirror on 2x2 off-row target (diagonal offset) flips X only", "[IMEX]") {
    // 2x2 IMEX layout: primary T0 at rear-left, target T3 at front-right → diagonal
    // gantry_offset. Reflection plane must still be X-axis (same as on-row T1 mirror),
    // not the diagonal direction — otherwise T3's ghost reads as rotated ~45° in plan
    // view (the bug this test guards against). Primary origin (0,0,0) maps to target
    // origin (100,100,0) regardless.
    const Vec2d offset{100.0, 100.0};
    Transform3d xf = imex_head_transform(0, 3, ImexRole::Mirror, offset);

    const Vec3d mapped = xf * Vec3d::Zero();
    REQUIRE_THAT(mapped.x(), WithinAbs(100.0, 1e-9));
    REQUIRE_THAT(mapped.y(), WithinAbs(100.0, 1e-9));
    REQUIRE_THAT(mapped.z(), WithinAbs(0.0,   1e-9));

    // A model point offset +5 X from primary ends up 5 LEFT of the ghost origin
    // (X flipped), while Y translates 1:1 (Y unflipped).
    const Vec3d in{5.0, 7.0, 0.0};
    const Vec3d out = xf * in;
    REQUIRE_THAT(out.x(), WithinAbs(95.0,  1e-9));   // 100 - 5
    REQUIRE_THAT(out.y(), WithinAbs(107.0, 1e-9));   // 100 + 7
}

TEST_CASE("resolve_filament_for_head — no routing returns -1 (ghost color fallback)", "[IMEX]") {
    // User's IQEX pem: T0 has 4 AFC lanes, T1/T2/T3 direct. T5 is unrouted.
    auto pem = make_pem({0, 0, 0, 0, 1, 2, 3});
    std::map<int,int> no_override;
    REQUIRE(resolve_filament_for_head(no_override, pem, 5) == -1);

    // Plate override for an unrouted head still resolves (user's explicit choice wins).
    std::map<int,int> override_on_5 = {{5, 7}};
    REQUIRE(resolve_filament_for_head(override_on_5, pem, 5) == 6);
}