diff --git a/AGENTS.md b/AGENTS.md
index 04b1c29..5e3d96b 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -171,8 +171,9 @@ Design specs and plans are not kept in this repo; they live under
 - `Kind` is a keyword: no type of that name.
 - `bend x.bend` runs main after checking. To check only, `bend <file.bend> --check-only` (or `bend x.bend -o t.js`).
 - A foreign effect `def a.b(..) -> IO(T)` with `import "./x.c"` and
-  `import "./x.js"` bodies is `a_b_run` + `io_eff(CID_A_B, ..)` in C and
-  `function a_b(..)` in JS (src/lsp/checker/exec.*).
+  `import "./x.js"` bodies registers itself on both lanes by its def name:
+  `io_eff(CID(a.b), a_b_run, 0)` in C and `io_eff(CID(a.b), a_b)` in JS
+  (bend 2.0.28; `bend guide effects`, src/lsp/checker/exec.*).
 - A server's stdin and stdout may be sockets (node spawns children that way),
   and no path opens a socket: wrap descriptors 0 and 1 (src/lsp/transport/fd.c),
   never `File.open("/dev/stdin")`. Test a server spawned from node
diff --git a/README.md b/README.md
index 5572a2c..235f69b 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ bolt needs a Bend 2, and any Bend 2 will do: the one
 one built from source. You do not need ez or nix. Building bolt needs clang
 14+ as well, since bolt is one native binary.
 
-**Bend version.** bolt is built and tested with Bend 2.0.27, the version
+**Bend version.** bolt is built and tested with Bend 2.0.28, the version
 `flake.lock` pins. `bolt check` and `bolt lsp` run the `bend` on your PATH,
 so that `bend` is the one to keep at the tested version.
 
diff --git a/ez.lock.toml b/ez.lock.toml
index 4ceafbe..2af1462 100644
--- a/ez.lock.toml
+++ b/ez.lock.toml
@@ -17,29 +17,6 @@ LICENSE = "309f5aae946e4db157750e002fb179a74ed0fe27fce09a7be68a6977b14f205f"
 "src/args.bend" = "cb408b31dc02aa0525dc07f7a3119798f6d1d96f244361dc941797bb90653b24"
 "src/check.bend" = "ad47c820def9bb1b77ea52b8097e4a62a7f1bbe6aac3c753ddf089c29f9c012a"
 "src/cli.bend" = "c8b1c75699e77ca233aac1125cff8565246ae230aee25752c52f05e608f41362"
-[packages.0x103d0af04de36ab98b311e537366ec67]
-[packages.0x103d0af04de36ab98b311e537366ec67.source]
-kind = "git"
-url = "https://github.com/Emerging-Patterns/snap"
-rev = "ced24e103db518e37f565c577ef312602c217cf5"
-entry = "main.bend"
-root = "."
-narHash = "sha256-dEO94GFkcgssyzOqz4A5VveB3npPq4/zpDpI+EvqnvI="
-tag = "v1.0.0"
-[packages.0x103d0af04de36ab98b311e537366ec67.files]
-LICENSE = "309f5aae946e4db157750e002fb179a74ed0fe27fce09a7be68a6977b14f205f"
-"main.bend" = "68a5a2f373983f652dc260683c57261930bbe1fba3b89f05973066697a4e8d43"
-"src/answer.bend" = "cfeb97ada7d0708c49abae1164af3e988a32c7fbdfb6591c61ce148b46d0738d"
-"src/argv.bend" = "6a3a6e8669fb5dab77f843fdd778402593d898c52a0dcd8738b689d95ff35856"
-"src/effect.bend" = "d0db20f66f1d55128b865d369a6bccfe8353dc05ec7f8b1b9576317ecaba8d8d"
-"src/exec.c" = "76f3490075a1640af38dc0422f9e9ebe849f60ad6e9b001f97313dbdaa03880d"
-"src/exec.js" = "0a4f99c247fd0e8346b6f541ceeb67e477e450332c5c1942a082280af75bc986"
-"src/file.bend" = "261a8f461bf0203e3e33bb3dfe0e21f88b1be1ffad8d9bb088827dcd3904c8f8"
-"src/par.bend" = "c5c316830a377d4f6b5390e12e0dd886f00351d882e6e8803b3514491bf5964e"
-"src/par.c" = "4843bf8fa1e76c69cf33fa769fa4b8e9f22df69aff990cb5a3de08ecfe9034bc"
-"src/par.js" = "791ced8192ca1d7238919629db661bfd3799db24d9483b397052e054f12d4225"
-"src/start.c" = "7306425871c0d4b859c6809f34b83ae7947b2065781fd2a8fe8ac8806a77391b"
-"src/start.js" = "d45eca4a2782e3fdbc1b7abc798fc3f131dc87dde34ab9cfa6dd917fff2ea04c"
 [packages.0x81c67699424929b5c44cd8577e18117f]
 [packages.0x81c67699424929b5c44cd8577e18117f.source]
 kind = "git"
@@ -58,3 +35,26 @@ LICENSE = "309f5aae946e4db157750e002fb179a74ed0fe27fce09a7be68a6977b14f205f"
 "src/print.bend" = "32a92e32f9e58cb028c59209c6aeb2b408f0510d199b31cff172c09bbb68fd6a"
 "src/pull.bend" = "c682f4f968f78b10bf39351130aa48fc9ade47c01f5bb2b4b74a061df7afb141"
 "src/value.bend" = "e4fe80f757464b9c35e298b921c1a6562e4e9251c779774b0d8873f46129e8e7"
+[packages.0xabe575924687afad4cee1a2c1194d639]
+[packages.0xabe575924687afad4cee1a2c1194d639.source]
+kind = "git"
+url = "https://github.com/Emerging-Patterns/snap"
+rev = "fcabc81830c9e21d86d4968810285b287da49c12"
+entry = "main.bend"
+root = "."
+narHash = "sha256-uKIWgjm98bQAYaNiMD/UOfwg55LWcAj2oC9AzSQuNBA="
+tag = "v1.1.0"
+[packages.0xabe575924687afad4cee1a2c1194d639.files]
+LICENSE = "309f5aae946e4db157750e002fb179a74ed0fe27fce09a7be68a6977b14f205f"
+"main.bend" = "68a5a2f373983f652dc260683c57261930bbe1fba3b89f05973066697a4e8d43"
+"src/answer.bend" = "cfeb97ada7d0708c49abae1164af3e988a32c7fbdfb6591c61ce148b46d0738d"
+"src/argv.bend" = "6a3a6e8669fb5dab77f843fdd778402593d898c52a0dcd8738b689d95ff35856"
+"src/effect.bend" = "d0db20f66f1d55128b865d369a6bccfe8353dc05ec7f8b1b9576317ecaba8d8d"
+"src/exec.c" = "1478ed5e6315c40f220bfa717d1d6a32103446641e713593c5f6557f484c607e"
+"src/exec.js" = "70268064b34529d651b670fb180027703d15ec494f6ea9dd7dcfc878dbb30a74"
+"src/file.bend" = "261a8f461bf0203e3e33bb3dfe0e21f88b1be1ffad8d9bb088827dcd3904c8f8"
+"src/par.bend" = "c5c316830a377d4f6b5390e12e0dd886f00351d882e6e8803b3514491bf5964e"
+"src/par.c" = "7edbca9e791b0d202e78543e7863b8d74d38e79b7f1fcb645dd15fbdb6ffcde0"
+"src/par.js" = "33ff4eca5d524264d28da36a9caf0a8252036efd44b92358a4c07daeb3ba69c9"
+"src/start.c" = "1bec197312b644549c176463e9476986301b28f6e01e5c34ea508f396cda1aec"
+"src/start.js" = "8ea49fe5324a2608342b4629b29d841a81d72ee8006869ac06971a0fb1aed53a"
diff --git a/ez.toml b/ez.toml
index fb389ab..d344188 100644
--- a/ez.toml
+++ b/ez.toml
@@ -1,7 +1,7 @@
 [package]
 name = "bolt"
 entry = "main.bend"
-
+[deps]
 [deps.ezjson]
 hash = "0x81c67699424929b5c44cd8577e18117f"
 git = "https://github.com/Emerging-Patterns/ezjson"
@@ -10,16 +10,14 @@ tag = "v1.1.0"
 root = "."
 narHash = "sha256-yHxl1aW4luf2bdPqOUcULhOEZLlcaTOWjTrPJys4CMI="
 entry = "main.bend"
-
 [deps.snap]
-hash = "0x103d0af04de36ab98b311e537366ec67"
+hash = "0xabe575924687afad4cee1a2c1194d639"
 git = "https://github.com/Emerging-Patterns/snap"
-rev = "ced24e103db518e37f565c577ef312602c217cf5"
-tag = "v1.0.0"
+rev = "fcabc81830c9e21d86d4968810285b287da49c12"
+tag = "v1.1.0"
 root = "."
-narHash = "sha256-dEO94GFkcgssyzOqz4A5VveB3npPq4/zpDpI+EvqnvI="
+narHash = "sha256-uKIWgjm98bQAYaNiMD/UOfwg55LWcAj2oC9AzSQuNBA="
 entry = "main.bend"
-
 [deps.shake]
 hash = "0x085b03c84ca37125e38dddede7b91e55"
 git = "https://github.com/Emerging-Patterns/shake"
diff --git a/flake.lock b/flake.lock
index 55e5bef..6ac021f 100644
--- a/flake.lock
+++ b/flake.lock
@@ -7,11 +7,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1790348040,
-        "narHash": "sha256-6oh+6jj7kyl4xJsmq4p3BtU/BUl2f2LlC/5kH081D1M=",
+        "lastModified": 1790359392,
+        "narHash": "sha256-z0Xwg46QesyRnlb7+sQue2GRq90v9M2XVaNVVSdd5Vs=",
         "owner": "bendlang",
         "repo": "bend",
-        "rev": "774ef644dccf9c3f8053f7276d8901ad23da006c",
+        "rev": "11c65a2572e16d0bfc2e83068b23ed8fb180ccc0",
         "type": "github"
       },
       "original": {
@@ -20,11 +20,28 @@
         "type": "github"
       }
     },
+    "bend_2": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      },
+      "locked": {
+        "lastModified": 1790200275,
+        "narHash": "sha256-huYLnKbMUukFhFLypIXx/wLVU3EmgsUEe9l67mU6CDw=",
+        "owner": "bendlang",
+        "repo": "bend",
+        "rev": "d37909174ebd664338ae3194799a9e0899dedd51",
+        "type": "github"
+      },
+      "original": {
+        "owner": "bendlang",
+        "repo": "bend",
+        "rev": "d37909174ebd664338ae3194799a9e0899dedd51",
+        "type": "github"
+      }
+    },
     "ez": {
       "inputs": {
-        "bend": [
-          "bend"
-        ],
+        "bend": "bend_2",
         "nixpkgs": [
           "nixpkgs"
         ]
@@ -44,6 +61,22 @@
       }
     },
     "nixpkgs": {
+      "locked": {
+        "lastModified": 1790185690,
+        "narHash": "sha256-xJ+X4hBtOcAFGBOe5nAMyMUeF9foJBmIOu3NjBqBycU=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "4975466d324710c576dc11ad614684e6bd8cad8e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
       "locked": {
         "lastModified": 1789546076,
         "narHash": "sha256-zVxLZiSnmaaPLwnhj7pwmqe3axBg/C6nG5JZsJMh2g4=",
@@ -63,7 +96,7 @@
       "inputs": {
         "bend": "bend",
         "ez": "ez",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs_2"
       }
     }
   },
diff --git a/flake.nix b/flake.nix
index ba0f6fd..7e320df 100644
--- a/flake.nix
+++ b/flake.nix
@@ -9,7 +9,9 @@
   inputs.ez = {
     url = "github:Emerging-Patterns/ez";
     inputs.nixpkgs.follows = "nixpkgs";
-    inputs.bend.follows = "bend";
+    # not `inputs.bend.follows = "bend"`: ez 1.2.0 does not build on bend
+    # 2.0.28, so ez (and `ez prove`) keep the bend ez 1.2.0 locks, 2.0.27
+    inputs.bend.url = "github:bendlang/bend/d37909174ebd664338ae3194799a9e0899dedd51";
   };
 
   outputs = { self, nixpkgs, ... }@inputs:
diff --git a/src/LAWS.bend b/src/LAWS.bend
index 20fb79d..d0aec00 100644
--- a/src/LAWS.bend
+++ b/src/LAWS.bend
@@ -35,22 +35,22 @@ law set_level_none:
 # LAW: a setting of the name, first in file order, is the name's setting
 # BOLT-CFG-1
 law set_level_first:
-  for sets: List<&2, Config.Set>
+  for sets: List<&2, Config.LevelSet>
   for +name: String
   for +nn: String
   for ll: Config.Level
   for h: {String.eq(nn, name) == True{} : Bool}
-  {Config.set_level(Config.Set{nn, ll} <> sets, name) == Some{ll} : Maybe<&2, Config.Level>}
+  {Config.set_level(Config.LevelSet{nn, ll} <> sets, name) == Some{ll} : Maybe<&2, Config.Level>}
 
 # LAW: a setting of another name is passed over
 # BOLT-CFG-1
 law set_level_skip:
-  for +sets: List<&2, Config.Set>
+  for +sets: List<&2, Config.LevelSet>
   for +name: String
   for +nn: String
   for ll: Config.Level
   for h: {String.eq(nn, name) == False{} : Bool}
-  {Config.set_level(Config.Set{nn, ll} <> sets, name) == Config.set_level(sets, name)
+  {Config.set_level(Config.LevelSet{nn, ll} <> sets, name) == Config.set_level(sets, name)
     : Maybe<&2, Config.Level>}
 
 # LAW: a rule's own setting is its level, whatever its group says, an
@@ -58,7 +58,7 @@ law set_level_skip:
 # BOLT-CFG-1
 # BOLT-CFG-6
 law level_own:
-  for +sets: List<&2, Config.Set>
+  for +sets: List<&2, Config.LevelSet>
   for +group: String
   for +rule: String
   for +l: Config.Level
@@ -69,7 +69,7 @@ law level_own:
 # setting
 # BOLT-CFG-1
 law level_group:
-  for +sets: List<&2, Config.Set>
+  for +sets: List<&2, Config.LevelSet>
   for +group: String
   for +rule: String
   for +l: Config.Level
@@ -82,7 +82,7 @@ law level_group:
 # setting either, is at its group's default
 # BOLT-CFG-1
 law level_default:
-  for +sets: List<&2, Config.Set>
+  for +sets: List<&2, Config.LevelSet>
   for +group: String
   for +rule: String
   for h_rule: {Config.set_level(sets, rule) == None{} : Maybe<&2, Config.Level>}
@@ -153,7 +153,7 @@ law default_rest:
 # says (with one, level_own gives it that setting)
 # BOLT-CFG-6
 law opt_in_off:
-  for +sets: List<&2, Config.Set>
+  for +sets: List<&2, Config.LevelSet>
   for +group: String
   for +rule: String
   for h_opt: {Config.opt_in(rule) == True{} : Bool}
diff --git a/src/config.bend b/src/config.bend
index 9032819..54670ae 100644
--- a/src/config.bend
+++ b/src/config.bend
@@ -29,12 +29,12 @@ type Level is Data:
   Error{}
 
 # a name (a group's or a rule's) at a level
-type Set is Data:
-  Set{name: String, level: Level}
+type LevelSet is Data:
+  LevelSet{name: String, level: Level}
 
 # the settings, in file order
 type Config is Data:
-  Config{sets: List<&2, Set>}
+  Config{sets: List<&2, LevelSet>}
 
 # no file: the defaults
 def none() -> Config:
@@ -89,18 +89,18 @@ def first_str(toks: List<&2, Lex.Tok>) -> Maybe<&2, String>:
       first_str(rest)
 
 # a def's name and the string it returns, as a setting
-def setting(name: Maybe<&2, String>, word: Maybe<&2, String>) -> List<&2, Set>:
+def setting(name: Maybe<&2, String>, word: Maybe<&2, String>) -> List<&2, LevelSet>:
   match name word:
     case Some{n} Some{w}:
-      [Set{n, of_word(w)}]
+      [LevelSet{n, of_word(w)}]
     case a b:
       []
 
 # every `def x(): "level"` of a tree
-def sets(root: Tree.Node) -> List<&2, Set>:
+def sets(root: Tree.Node) -> List<&2, LevelSet>:
   match root:
     case Tree.NCons{Tree.Stmt{Tree.SDef{}, kids, body}, rest}:
-      List.append(&2, Set, setting(Bind.declared(kids), first_str(Tree.leaves(body))), sets(rest))
+      List.append(&2, LevelSet, setting(Bind.declared(kids), first_str(Tree.leaves(body))), sets(rest))
     case Tree.NCons{h, rest}:
       sets(rest)
     case other:
@@ -203,11 +203,11 @@ def nearest(rs: List<&2, Maybe<&2, String>>) -> Config:
 # ------
 
 # the level a name is set to, when it is
-def set_level(sets: List<&2, Set>, +name: String) -> Maybe<&2, Level>:
+def set_level(sets: List<&2, LevelSet>, +name: String) -> Maybe<&2, Level>:
   match sets:
     case Nil{}:
       None{}
-    case Con{Set{+n, l}, rest}:
+    case Con{LevelSet{+n, l}, rest}:
       +more = set_level(rest, name)
       Bool.pick(Maybe<&2, Level>, String.eq(n, name), Some{l}, more)
 
@@ -223,7 +223,7 @@ def opt_in(+rule: String) -> Bool:
 
 # the rule's own setting, else its group's, else the group's default; an
 # opt-in rule's own setting, else off
-def level.of(+sets: List<&2, Set>, +group: String, +rule: String) -> Level:
+def level.of(+sets: List<&2, LevelSet>, +group: String, +rule: String) -> Level:
   Maybe.default(&2, Level, set_level(sets, rule),
     Lazy.stop(Level, opt_in(rule), Off{}, _u => Maybe.default(&2, Level, set_level(sets, group), default(group))))
 
diff --git a/src/lsp/checker/exec.c b/src/lsp/checker/exec.c
index 11a9648..db7c0f4 100644
--- a/src/lsp/checker/exec.c
+++ b/src/lsp/checker/exec.c
@@ -74,7 +74,7 @@ Term bendcheck_exec_run(Env e, Term* f, IoWork* w) {
 }
 
 static void __attribute__((constructor)) bendcheck_exec_use(void) {
-  io_eff(CID_BENDCHECK_EXEC, bendcheck_exec_run, 0);
+  io_eff(CID(bendcheck.exec), bendcheck_exec_run, 0);
 }
 
 // `bolt lsp` with no `--gpu` is `--gpu off`. The runtime chooses the device
diff --git a/src/lsp/checker/exec.js b/src/lsp/checker/exec.js
index 7509ab5..26b991b 100644
--- a/src/lsp/checker/exec.js
+++ b/src/lsp/checker/exec.js
@@ -9,3 +9,5 @@ function bendcheck_exec(path, flag) {
   const tag = r.status === 127 || (r.error && r.status === null && r.signal === null) ? "x" : r.signal ? "s" : "r";
   return tag + (r.stdout ?? "") + (r.stderr ?? "");
 }
+
+io_eff(CID(bendcheck.exec), bendcheck_exec);
diff --git a/src/lsp/transport/fd.c b/src/lsp/transport/fd.c
index 50e13ed..4d9ea6f 100644
--- a/src/lsp/transport/fd.c
+++ b/src/lsp/transport/fd.c
@@ -6,5 +6,5 @@ Term stdio_fd_run(Env e, Term* f, IoWork* w) {
 }
 
 static void __attribute__((constructor)) stdio_fd_use(void) {
-  io_eff(CID_STDIO_FD, stdio_fd_run, 0);
+  io_eff(CID(stdio.fd), stdio_fd_run, 0);
 }
diff --git a/src/lsp/transport/fd.js b/src/lsp/transport/fd.js
index 65d6c85..6f39fe1 100644
--- a/src/lsp/transport/fd.js
+++ b/src/lsp/transport/fd.js
@@ -2,3 +2,5 @@
 function stdio_fd(n) {
   return n;
 }
+
+io_eff(CID(stdio.fd), stdio_fd);
diff --git a/src/walk/cwd.c b/src/walk/cwd.c
index dab0518..1cfb7a1 100644
--- a/src/walk/cwd.c
+++ b/src/walk/cwd.c
@@ -13,5 +13,5 @@ Term walkdir_cwd_run(Env e, Term* f, IoWork* w) {
 }
 
 static void __attribute__((constructor)) walkdir_cwd_use(void) {
-  io_eff(CID_WALKDIR_CWD, walkdir_cwd_run, 0);
+  io_eff(CID(walkdir.cwd), walkdir_cwd_run, 0);
 }
diff --git a/src/walk/cwd.js b/src/walk/cwd.js
index a914a20..218efe4 100644
--- a/src/walk/cwd.js
+++ b/src/walk/cwd.js
@@ -7,3 +7,5 @@ function walkdir_cwd() {
     return "";
   }
 }
+
+io_eff(CID(walkdir.cwd), walkdir_cwd);
diff --git a/src/walk/dir.c b/src/walk/dir.c
index 2960492..b3fa8b4 100644
--- a/src/walk/dir.c
+++ b/src/walk/dir.c
@@ -59,5 +59,5 @@ Term walkdir_entries_run(Env e, Term* f, IoWork* w) {
 }
 
 static void __attribute__((constructor)) walkdir_entries_use(void) {
-  io_eff(CID_WALKDIR_ENTRIES, walkdir_entries_run, 0);
+  io_eff(CID(walkdir.entries), walkdir_entries_run, 0);
 }
diff --git a/src/walk/dir.js b/src/walk/dir.js
index 115bc32..d69956b 100644
--- a/src/walk/dir.js
+++ b/src/walk/dir.js
@@ -12,3 +12,5 @@ function walkdir_entries(dir) {
   }
   return entries.map((e) => e.name + (e.isDirectory() ? "/" : "") + "\n").join("");
 }
+
+io_eff(CID(walkdir.entries), walkdir_entries);
diff --git a/tests/bare.bend b/tests/bare.bend
index f714e34..4608209 100644
--- a/tests/bare.bend
+++ b/tests/bare.bend
@@ -18,7 +18,7 @@
 # it, and it is the slow one, because the compile it drives is a whole build of
 # bolt.
 import Base
-import 0x103d0af04de36ab98b311e537366ec67/main.bend as Snap
+import 0xabe575924687afad4cee1a2c1194d639/main.bend as Snap
 
 # `ok name` when the two strings are equal, `FAIL name` when they are not
 def eq_str(name: String, got: String, want: String) -> IO(Unit):
@@ -32,9 +32,9 @@ def shake.hash() -> String:
 def ezjson.hash() -> String:
   "0x81c67699424929b5c44cd8577e18117f"
 
-# the 0x name ez computed for snap v1.0.0
+# the 0x name ez computed for snap v1.1.0
 def snap.hash() -> String:
-  "0x103d0af04de36ab98b311e537366ec67"
+  "0xabe575924687afad4cee1a2c1194d639"
 
 # the build, with ez taken out of the environment. BEND_LIB is the
 # checkouts this test laid out, not ez's.