diff --git a/flake.lock b/flake.lock
index 2a6d737d..d6d60c70 100644
--- a/flake.lock
+++ b/flake.lock
@@ -18,17 +18,54 @@
         "type": "github"
       }
     },
+    "flake-utils_2": {
+      "inputs": {
+        "systems": "systems_2"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "lowrisc-nix": {
+      "inputs": {
+        "flake-utils": "flake-utils_2",
+        "nixpkgs": "nixpkgs"
+      },
+      "locked": {
+        "lastModified": 1783357944,
+        "narHash": "sha256-uvsq+827sCrOUdcALh83bN4ngp6Hms8KdmE9mgEzmIo=",
+        "owner": "lowRISC",
+        "repo": "lowrisc-nix",
+        "rev": "4db34a757ba4f21ea82846ff4f43e6f61bd43caa",
+        "type": "github"
+      },
+      "original": {
+        "owner": "lowRISC",
+        "repo": "lowrisc-nix",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1780203844,
         "narHash": "sha256-K5sT4jTpGs15ADhviMKNBH38REpPf5Q6mM1+N6cArVE=",
-        "owner": "nixos",
+        "owner": "NixOS",
         "repo": "nixpkgs",
         "rev": "b51242d7d43689db2f3be91bd05d5b24fbb469c4",
         "type": "github"
       },
       "original": {
-        "owner": "nixos",
+        "owner": "NixOS",
         "ref": "nixos-26.05",
         "repo": "nixpkgs",
         "type": "github"
@@ -36,11 +73,11 @@
     },
     "nixpkgs-unstable": {
       "locked": {
-        "lastModified": 1775423009,
-        "narHash": "sha256-vPKLpjhIVWdDrfiUM8atW6YkIggCEKdSAlJPzzhkQlw=",
+        "lastModified": 1783224372,
+        "narHash": "sha256-8i/87eeoqiGE4yOTjwSA3Eh/ziJRQEmd/unYU+K27sk=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "68d8aa3d661f0e6bd5862291b5bb263b2a6595c9",
+        "rev": "d407951447dcd00442e97087bf374aad70c04cea",
         "type": "github"
       },
       "original": {
@@ -50,6 +87,22 @@
         "type": "github"
       }
     },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1783148766,
+        "narHash": "sha256-uslt2pqShTIXDdAHRHv2QkYLsVdY8Oqwz0EA48/RSM8=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "a50de1b7d8a586adc18d2395c19de7d6058e6030",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-26.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "pyproject-build-systems": {
       "inputs": {
         "nixpkgs": [
@@ -63,11 +116,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1773870109,
-        "narHash": "sha256-ZoTdqZP03DcdoyxvpFHCAek4bkPUTUPUF3oCCgc3dP4=",
+        "lastModified": 1782093830,
+        "narHash": "sha256-6gmEVe69+KlRkZD4PEEV5xAlB9CB0Y9TiuEgQjDrKTQ=",
         "owner": "pyproject-nix",
         "repo": "build-system-pkgs",
-        "rev": "b6e74f433b02fa4b8a7965ee24680f4867e2926f",
+        "rev": "430680a19bc85a3bda55f12e4cc1a1aadcf2e478",
         "type": "github"
       },
       "original": {
@@ -83,11 +136,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1775439158,
-        "narHash": "sha256-NHY9SJNU019n+8NCabBDtmuzRFeE2gZlYKHowp9bV24=",
+        "lastModified": 1782905613,
+        "narHash": "sha256-SvXJcAemihifkTn4BGvyE5K1FJX9bl4U8DQ5pqKvD0s=",
         "owner": "nix-community",
         "repo": "pyproject.nix",
-        "rev": "fb6b728260f3f32761367e9fd1e1a25b4245bcd0",
+        "rev": "7af23cfe91064865ecf2e835da28b45b3c6f49fd",
         "type": "github"
       },
       "original": {
@@ -99,7 +152,8 @@
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
-        "nixpkgs": "nixpkgs",
+        "lowrisc-nix": "lowrisc-nix",
+        "nixpkgs": "nixpkgs_2",
         "nixpkgs-unstable": "nixpkgs-unstable",
         "pyproject-build-systems": "pyproject-build-systems",
         "pyproject-nix": "pyproject-nix",
@@ -121,6 +175,21 @@
         "type": "github"
       }
     },
+    "systems_2": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    },
     "uv2nix": {
       "inputs": {
         "nixpkgs": [
@@ -131,11 +200,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1775386139,
-        "narHash": "sha256-n82p7WF+dYxf5r01pXlqbk8CAF7xX0Tk7wAcmMjkuhc=",
+        "lastModified": 1783307743,
+        "narHash": "sha256-oseisp2tblvzYZdojkA5URLnMjrpPiemzr5T7BdUyuU=",
         "owner": "pyproject-nix",
         "repo": "uv2nix",
-        "rev": "3cffcee173635d553e213d11418690b5290ff1c9",
+        "rev": "288b0a580ede39d3d7f96e3d835f9df0a7080223",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 291071e7..652a5bc2 100644
--- a/flake.nix
+++ b/flake.nix
@@ -25,6 +25,8 @@
       inputs.uv2nix.follows = "uv2nix";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+
+    lowrisc-nix.url = "github:lowRISC/lowrisc-nix";
   };
 
   outputs = {
@@ -35,6 +37,7 @@
     uv2nix,
     pyproject-nix,
     pyproject-build-systems,
+    lowrisc-nix,
     ...
   }:
     flake-utils.lib.eachDefaultSystem (system: let
@@ -126,6 +129,11 @@
       };
 
       devShells = {
+        # Lightweight Python dev shell. This is the direnv-loaded default
+        # (`use flake` in .envrc): direnv sources a shell's environment into the
+        # current shell, so it must be a plain mkShell — the FHS EDA shell below
+        # cannot be sourced (it execs into a bubblewrap mount namespace), which
+        # is why it is a *separate* shell entered explicitly with `nix develop`.
         default = pkgs.mkShell {
           packages = [
             python
@@ -151,6 +159,21 @@
             export LD_LIBRARY_PATH="${lib.makeLibraryPath [pkgs.stdenv.cc.cc.lib pkgs.zlib]}''${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}"
           '';
         };
+
+        # EDA tool shell driven by lowrisc-nix's generic mkEdaShell. Enter with
+        # `nix develop .#eda` (it execs into a hermetic FHS sandbox, so it is not
+        # direnv-loadable). Tool paths/licenses come at runtime from the JSON
+        # file named by $LOWRISC_EDA_CONFIG; without it the shell still works and
+        # just warns. Bundles the dvsim virtualenv so dvsim can drive the tools.
+        eda = lowrisc-nix.lib.mkEdaShell {
+          inherit pkgs;
+          name = "dvsim-eda";
+          tools = {
+            cadence.xcelium = "23.09.002";
+            synopsys.vcs = "X-2025.06-SP2-1";
+          };
+          extraDeps = [self.packages.${system}.default];
+        };
       };
 
       checks = {inherit (pythonSet.dvsim.passthru.tests) pytest;};