diff --git a/.github/scripts/build-contract-shell.sh b/.github/scripts/build-contract-shell.sh
index 3845a1d..9fbc79c 100755
--- a/.github/scripts/build-contract-shell.sh
+++ b/.github/scripts/build-contract-shell.sh
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# Wraps the Dhall-generated package (from tests/Exhaustive.dhall) in a minimal
+# Wraps the Dhall-generated package (from demos/Exhaustive.dhall) in a minimal
 # consumer shell, mirroring the hand-written tests/golden/ shell (pyproject.toml
 # + py.typed) so basedpyright strict runs against the same layout a real
 # consumer would import, per the full_package pattern in tests/conftest.py.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7664a04..b5d526f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -121,7 +121,7 @@ jobs:
         with:
           ref: ${{ inputs.ref || github.sha }}
 
-      # The `as Source` import mode on gen/Deps only changes how pgn loads the
+      # The `as Source` import mode on src/Deps only changes how pgn loads the
       # remote packages (unnormalized, to save RAM), not what they evaluate to.
       # The pinned action below bundles a dhall fork that predates the mode, so
       # strip it here; the evaluation is semantically identical either way. The
@@ -132,16 +132,16 @@ jobs:
         shell: bash
         run: |
           set -euo pipefail
-          sed -i -e 's/^[[:space:]]*as Source$//' -e 's/^[[:space:]]*sha256:[0-9a-f]\{64\}$//' gen/Deps/*.dhall
+          sed -i -e 's/^[[:space:]]*as Source$//' -e 's/^[[:space:]]*sha256:[0-9a-f]\{64\}$//' src/Deps/*.dhall
 
-      # A plain, standard-Dhall evaluator cannot run this: gen/Interpreters/Project.dhall's
+      # A plain, standard-Dhall evaluator cannot run this: src/Interpreters/Project.dhall's
       # buildLookup and gen-sdk's own Fixtures.Exhaustive both use Text/equal, a builtin
       # from pgn's forked Dhall, absent from the upstream dhall-lang Prelude. This action
       # bundles that same fork.
       - name: Generate output from Dhall
         uses: nikita-volkov/dhall-directory-tree.github-action@60a18dc647d6daea805263ea0fed7bb8011f3bcd # v2
         with:
-          dhall_file: tests/Exhaustive.dhall
+          dhall_file: demos/Exhaustive.dhall
           output_dir: contract-output
 
       - name: Assert the compile did not fail
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 25e92c7..91764bc 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -86,7 +86,7 @@ jobs:
         id: resolve
         uses: nikita-volkov/dhall-resolve.github-action@7caaf1fdb40ac864bc02e37575f577ee084713a8 # v3
         with:
-          file: gen/Gen.dhall
+          file: src/package.dhall
           minify: true
 
       - name: Prepare changelog for release
diff --git a/AGENTS.md b/AGENTS.md
index f6d2533..7da3b7b 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -33,6 +33,6 @@ already says.
 
 ## Dhall
 
-`gen/` pins its remote imports by sha256 (`gen/Deps/*.dhall`). Bump those
+`src/` pins its remote imports by sha256 (`src/Deps/*.dhall`). Bump those
 deliberately, one at a time, and re-run the harness before committing a pin
 change.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8cc7b2c..f98fe04 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Upcoming
 
+- Migrated the generator's internal dependencies to `gen-contract` v4.0.1
+  and `gen-sdk` v2.0.0, adopting `Sdk.Sigs` in place of the local
+  `Algebras/` module, and restructured the repository layout to match the
+  pGenie generator architecture: implementation moved from `gen/` to
+  `src/`, the public entry point renamed from `gen/Gen.dhall` to
+  `src/package.dhall`, and the fixture driver moved from
+  `tests/Exhaustive.dhall` to `demos/Exhaustive.dhall`. No change to
+  generated output or the public Dhall interface (`artifacts.<name>.gen`
+  URLs pointing at a previously-released `resolved.dhall` are unaffected;
+  only the next release's URL path changes, from `.../gen/Gen.dhall` — the
+  unresolved source path some projects may reference directly instead of a
+  frozen release — to `.../src/package.dhall`).
 - The test harness now runs every pgn subprocess in its own process group under
   an RSS watchdog: a thread polls `ps -o rss=` every 2 s and, on breach of
   `PGN_MAX_RSS_GB` (default 40 GB), kills the whole group and fails the test with
diff --git a/DESIGN.md b/DESIGN.md
index bff5a2c..79e8a7c 100644
--- a/DESIGN.md
+++ b/DESIGN.md
@@ -1,7 +1,7 @@
 # python.gen DESIGN
 
 Status: current. This describes the generator as shipped, not a plan. The code
-is the source of truth: the Dhall generator under `gen/`, the fixture project
+is the source of truth: the Dhall generator under `src/`, the fixture project
 and golden output under `tests/`. When this doc and the tree disagree, the
 tree wins.
 
@@ -378,34 +378,37 @@ overwritten on every run. Do not hand-edit it.
 
 ## 10. Generator decomposition
 
-`gen/Gen.dhall` is the entry point handed to gen-sdk:
+`src/package.dhall` is the entry point handed to gen-sdk:
 
 ```dhall
 let Sdk = ./Deps/Sdk.dhall
 
-in  Sdk ./Config.dhall ./compile.dhall
+let Config = ./Config.dhall
+
+let interpret = ./Interpret.dhall
+
+in  Sdk.Sigs.generator Config Config/default interpret
 ```
 
-The Sdk `module` function has signature `\(Config : Type) -> \(compile) ->
-{ contractVersion, Config, compile, compileToFileMap }`, and
-`compile : Optional Config -> Project -> Lude.Compiled.Type Lude.Files.Type`,
-where `Files.Type = List { path : Text, content : Text }`. `compile.dhall`
-folds the optional user config into the internal interpreter config and
-calls `Interpreters/Project.dhall`, which traverses queries and custom types
-and assembles the file list.
+`Sdk.Sigs.generator` has signature `\(Config : Type) -> \(defaultConfig : Config) ->
+\(interpret : Config -> Contract.Project -> Contract.Output) -> ...`; it curries
+`interpret` against `defaultConfig` whenever the user config is absent and hands
+the result to gen-contract's `Contract.module`. `Interpret.dhall` folds the
+optional user config into the internal interpreter config and calls
+`Interpreters/Project.dhall`, which traverses queries and custom types and
+assembles the file list (`Contract.Output`).
 
-`gen/` mirrors a typical pgn gen-sdk generator, Python-flavored. The
-algebra/interpreter/template split keeps assembly separate from rendering.
+`src/` mirrors a typical pgn gen-sdk generator, Python-flavored: `Interpreters/`
+assembles data, `Templates/` renders it to Python text. The interpreter/template
+algebra signatures themselves live in gen-sdk's `Sdk.Sigs` (`interpreter.dhall`/
+`template.dhall`), not a local `Algebras/` dir.
 
 ```text
-gen/
-  Gen.dhall                  # Sdk Config compile  (entry handed to gen-sdk)
+src/
+  package.dhall              # Sdk.Sigs.generator Config Config/default interpret  (entry handed to gen-sdk)
   Config.dhall               # user config TYPE: { packageName, emitSync, onUnsupported }
-  compile.dhall               # derive interpreter Config from user Config, call Project.run
-  Deps/                      # pinned remote imports (gen-sdk module + Project, lude, Prelude)
-  Algebras/
-    Interpreter.dhall        # Config + `module Input Output run` ; Run = Config -> Input -> Compiled Output
-    Template.dhall           # `module Params run` ; Run = Params -> Text
+  Interpret.dhall            # derive interpreter Config from user Config, call Project.run
+  Deps/                      # pinned remote imports: gen-sdk, gen-contract, lude, dhall Prelude
   Structures/
     Surface.dhall            # async/sync token table (section 4)
     CustomKind.dhall         # Lookup : Name -> < Enum | Composite | Absent > + composite fields
@@ -426,6 +429,7 @@ gen/
     Project.dhall            # traverse queries+customTypes, assemble all files + facade + header,
                               # apply the Skip filter (section 11)
   Templates/
+    CoreModule.dhall         # shared _core.py: JsonValue, NoRowError/DecodeError, require_array
     RuntimeModule.dhall      # async + sync _runtime.py bodies
     RowsModule.dhall         # shared _rows.py (Row dataclasses + decode fns)
     StatementModule.dhall    # one per-surface statement wrapper
@@ -629,11 +633,11 @@ SQL rendering are largely driver-agnostic.
 
 CI runs two independent jobs (`.github/workflows/ci.yml`): `harness` (the
 pytest suite against a live Postgres) and `contract` (compiles gen-sdk's
-`Fixtures.Exhaustive` via `tests/Exhaustive.dhall` and runs basedpyright
+`Fixtures.Exhaustive` via `demos/Exhaustive.dhall` and runs basedpyright
 strict on the result). The `contract` job needs `nikita-volkov/dhall-directory-tree.github-action`,
 a Docker action bundling a forked Dhall evaluator; the local `dhall` CLI most
 people have installed is the standard dhall-lang build and does not
-understand `Text/equal`, so it cannot run `tests/Exhaustive.dhall` directly.
+understand `Text/equal`, so it cannot run `demos/Exhaustive.dhall` directly.
 Reproduce the `contract` job locally with [`act`](https://github.com/nektos/act)
 (not installed in this environment; `act -j contract` pulls the same pinned
 Docker action and runs the job as GitHub would).
diff --git a/README.md b/README.md
index db3226f..9e9a17f 100644
--- a/README.md
+++ b/README.md
@@ -35,7 +35,7 @@ name:
 ```yaml
 artifacts:
   python:
-    gen: https://raw.githubusercontent.com/slavashvets/python.gen/master/gen/Gen.dhall
+    gen: https://raw.githubusercontent.com/slavashvets/python.gen/master/src/package.dhall
     config:
       packageName: my-db-client
       emitSync: true
@@ -61,10 +61,10 @@ database.
 
 | form            | example                                | works?                                    |
 | --------------- | --------------------------------------- | ------------------------------------------ |
-| plain http(s)   | `https://.../python.gen/gen/Gen.dhall`  | yes; pgn fetches it and every relative import over HTTP |
-| relative path    | `../path/to/python.gen/gen/Gen.dhall`   | yes, if you keep a local checkout next to your project |
-| absolute path    | `/abs/path/to/python.gen/gen/Gen.dhall` | yes, but the resulting freeze key is machine-specific |
-| `file://` URL    | `file:///abs/.../Gen.dhall`             | rejected; pgn's project schema does not accept `file://` |
+| plain http(s)   | `https://.../python.gen/src/package.dhall`  | yes; pgn fetches it and every relative import over HTTP |
+| relative path    | `../path/to/python.gen/src/package.dhall`   | yes, if you keep a local checkout next to your project |
+| absolute path    | `/abs/path/to/python.gen/src/package.dhall` | yes, but the resulting freeze key is machine-specific |
+| `file://` URL    | `file:///abs/.../package.dhall`             | rejected; pgn's project schema does not accept `file://` |
 
 Whichever form you use, the freeze file that caches the resolved generator
 (section "Freeze lifecycle" below) keys on the literal `gen:` value and
diff --git a/bench/as-source.sh b/bench/as-source.sh
index 203b973..c16945b 100755
--- a/bench/as-source.sh
+++ b/bench/as-source.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 # Cold-cache benchmark of `pgn generate` on the fixture project, comparing the
-# current gen (Deps imported `as Source`) against the same tree with the
+# current src (Deps imported `as Source`) against the same tree with the
 # pre-as-Source Deps (plain pinned imports). Both variants run the same pgn
 # binary by default, so the measurement isolates the import mode itself.
 #
@@ -24,7 +24,7 @@ trap 'rm -rf "$work"' EXIT
 
 prepare() { # $1 = variant root; mirrors the repo layout the fixture expects
   rm -rf "$1" && mkdir -p "$1/tests"
-  cp -R "$root/gen" "$1/gen"
+  cp -R "$root/src" "$1/src"
   cp -R "$root/tests/fixture-project" "$1/tests/fixture-project"
   rm -f "$1/tests/fixture-project/freeze1.pgn.yaml"
   rm -rf "$1/tests/fixture-project/artifacts"
@@ -34,9 +34,23 @@ prepare() { # $1 = variant root; mirrors the repo layout the fixture expects
 # normalized-expression pins (an `as Source` pin hashes the import's source,
 # so the two modes need different sha256 values for the same version).
 strip_as_source() { # $1 = variant root
-  perl -i -ne 'print unless /^\s*as Source$/' "$1"/gen/Deps/*.dhall
-  perl -i -pe 's/8d43544ecb0e612406af3133bdbca51138c704a77a5a29ef62fe034d0e77a3a6/b9f7bb842345f3864c71e877fda4200306ba5c044a43e6f7713a23bc4769b91a/' "$1/gen/Deps/Sdk.dhall"
-  perl -i -pe 's/46b527b071eba96a17e76b4bc5774645714dd5b4355974d221e705aa7c126e77/14c43eec97972ae27afe3386ff937d04db66f84273d5551476361db12d2c4b50/' "$1/gen/Deps/Lude.dhall"
+  perl -i -ne 'print unless /^\s*as Source$/' "$1"/src/Deps/*.dhall
+
+  # gen-sdk v2.0.0's src/package.dhall: `mise x -- dhall hash` against the
+  # live GitHub-hosted package (both `... as Source` and the plain import)
+  # returns the SAME sha256 (b9def6ab1179bc4aaae7fc6e91977f094f75934cd5755175c294a9e97ca71b15),
+  # matching the value already committed in src/Deps/Sdk.dhall -- so, unlike
+  # the old v0.11.0 pin this pair used to target (where the two genuinely
+  # differed: 8d43544e...->b9f7bb84...), no character swap is needed here
+  # after the strip above; the committed pin already equals the plain-import
+  # target. See docs/superpowers/plans/2026-07-11-gen-sdk-v2-migration.md
+  # Task 6 for how this was verified (dhall's local import cache made the
+  # lookup instant; a cold, uncached fetch of a *different* URL hung in this
+  # sandbox, so treat network reachability here as best-effort, not given).
+
+  # lude v5.1.0 is unchanged by this migration (see src/Deps/Lude.dhall), so
+  # its existing as-Source -> plain-import hash swap below is still correct.
+  perl -i -pe 's/46b527b071eba96a17e76b4bc5774645714dd5b4355974d221e705aa7c126e77/14c43eec97972ae27afe3386ff937d04db66f84273d5551476361db12d2c4b50/' "$1/src/Deps/Lude.dhall"
 }
 
 measure() { # $1 = label, $2 = variant root, $3 = pgn binary
diff --git a/bench/generate.sh b/bench/generate.sh
index a2acd50..2769621 100755
--- a/bench/generate.sh
+++ b/bench/generate.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
-# Build the fixture client from the working-tree gen, in one of two variants:
-#   with    - gen/Deps as committed (imports `as Source`)
+# Build the fixture client from the working-tree src, in one of two variants:
+#   with    - src/Deps as committed (imports `as Source`)
 #   without - the pre-as-Source Deps (mode stripped, normalized-expression
 #             pins restored; byte-identical to commit fb78869's Deps)
 # Output lands in ./demo-with-as-source or ./demo-without-as-source.
@@ -15,15 +15,29 @@ url="${PGN_TEST_DATABASE_URL:-postgresql://postgres:postgres@localhost:5432/post
 out="$root/demo-$variant-as-source"
 
 rm -rf "$out" && mkdir -p "$out/tests"
-cp -R "$root/gen" "$out/gen"
+cp -R "$root/src" "$out/src"
 cp -R "$root/tests/fixture-project" "$out/tests/fixture-project"
 rm -f "$out/tests/fixture-project/freeze1.pgn.yaml"
 rm -rf "$out/tests/fixture-project/artifacts"
 
 if [ "$variant" = without ]; then
-  perl -i -ne 'print unless /^\s*as Source$/' "$out"/gen/Deps/*.dhall
-  perl -i -pe 's/8d43544ecb0e612406af3133bdbca51138c704a77a5a29ef62fe034d0e77a3a6/b9f7bb842345f3864c71e877fda4200306ba5c044a43e6f7713a23bc4769b91a/' "$out/gen/Deps/Sdk.dhall"
-  perl -i -pe 's/46b527b071eba96a17e76b4bc5774645714dd5b4355974d221e705aa7c126e77/14c43eec97972ae27afe3386ff937d04db66f84273d5551476361db12d2c4b50/' "$out/gen/Deps/Lude.dhall"
+  perl -i -ne 'print unless /^\s*as Source$/' "$out"/src/Deps/*.dhall
+
+  # gen-sdk v2.0.0's src/package.dhall: `mise x -- dhall hash` against the
+  # live GitHub-hosted package (both `... as Source` and the plain import)
+  # returns the SAME sha256 (b9def6ab1179bc4aaae7fc6e91977f094f75934cd5755175c294a9e97ca71b15),
+  # matching the value already committed in src/Deps/Sdk.dhall -- so, unlike
+  # the old v0.11.0 pin this pair used to target (where the two genuinely
+  # differed: 8d43544e...->b9f7bb84...), no character swap is needed here
+  # after the strip above; the committed pin already equals the plain-import
+  # target. See docs/superpowers/plans/2026-07-11-gen-sdk-v2-migration.md
+  # Task 6 for how this was verified (dhall's local import cache made the
+  # lookup instant; a cold, uncached fetch of a *different* URL hung in this
+  # sandbox, so treat network reachability here as best-effort, not given).
+
+  # lude v5.1.0 is unchanged by this migration (see src/Deps/Lude.dhall), so
+  # its existing as-Source -> plain-import hash swap below is still correct.
+  perl -i -pe 's/46b527b071eba96a17e76b4bc5774645714dd5b4355974d221e705aa7c126e77/14c43eec97972ae27afe3386ff937d04db66f84273d5551476361db12d2c4b50/' "$out/src/Deps/Lude.dhall"
 fi
 
 cd "$out/tests/fixture-project"
diff --git a/tests/Exhaustive.dhall b/demos/Exhaustive.dhall
similarity index 63%
rename from tests/Exhaustive.dhall
rename to demos/Exhaustive.dhall
index bfe8b84..35e8f28 100644
--- a/tests/Exhaustive.dhall
+++ b/demos/Exhaustive.dhall
@@ -1,9 +1,9 @@
 -- Applies this generator to gen-sdk's shared cross-backend fixture project
--- (the same "music_catalogue" project java.gen's own tests/Exhaustive.dhall
+-- (the same "music_catalogue" project java.gen's own demos/Exhaustive.dhall
 -- exercises), so a Python client compiles from it and passes basedpyright
 -- strict. Pinned directly at gen-sdk's package.dhall, separately from
--- gen/Deps/Sdk.dhall: that file only imports gen-sdk's `module.dhall` (the
--- generator-construction function), which has no `Fixtures` field.
+-- src/Deps/Sdk.dhall: that file only imports gen-sdk's `package.dhall` `as
+-- Source` for RAM, and this fixture load doesn't need that mode.
 --
 -- The fixture project deliberately covers PG types this generator does not
 -- support (box, inet, money, ranges, ...), so onUnsupported is set to Skip:
@@ -13,13 +13,13 @@
 -- Intended to be executed with:
 --
 -- ```bash
--- dhall to-directory-tree --file tests/Exhaustive.dhall --output <dir> --allow-path-separators
+-- dhall to-directory-tree --file demos/Exhaustive.dhall --output <dir> --allow-path-separators
 -- ```
-let Sdk = ../gen/Deps/Sdk.dhall
+let Sdk = ../src/Deps/Sdk.dhall
 
-let Gen = ../gen/Gen.dhall
+let Gen = ../src/package.dhall
 
-let OnUnsupported = ../gen/Structures/OnUnsupported.dhall
+let OnUnsupported = ../src/Structures/OnUnsupported.dhall
 
 let project = Sdk.Fixtures.Exhaustive
 
@@ -30,4 +30,4 @@ let config =
         , onUnsupported = Some OnUnsupported.Mode.Skip
         }
 
-in  Gen.compileToFileMap config project
+in  Sdk.Output.toFileMap (Gen.compile config project)
diff --git a/gen/Algebras/Interpreter.dhall b/gen/Algebras/Interpreter.dhall
deleted file mode 100644
index 7532153..0000000
--- a/gen/Algebras/Interpreter.dhall
+++ /dev/null
@@ -1,21 +0,0 @@
-let Deps = ../Deps/package.dhall
-
-let OnUnsupported = ../Structures/OnUnsupported.dhall
-
-let Config =
-      { packageName : Text
-      , importName : Text
-      , emitSync : Bool
-      , onUnsupported : OnUnsupported.Mode
-      }
-
-let module =
-      \(Input : Type) ->
-      \(Output : Type) ->
-        let Result = Deps.Lude.Compiled.Type Output
-
-        let Run = Config -> Input -> Result
-
-        in  \(run : Run) -> { Input, Output, Result, Run, run }
-
-in  { Config, module }
diff --git a/gen/Algebras/Template.dhall b/gen/Algebras/Template.dhall
deleted file mode 100644
index 15f2624..0000000
--- a/gen/Algebras/Template.dhall
+++ /dev/null
@@ -1,5 +0,0 @@
-let module =
-      \(Params : Type) ->
-        let Run = Params -> Text in \(run : Run) -> { Params, Run, run }
-
-in  { module }
diff --git a/gen/Algebras/package.dhall b/gen/Algebras/package.dhall
deleted file mode 100644
index f0f64bd..0000000
--- a/gen/Algebras/package.dhall
+++ /dev/null
@@ -1 +0,0 @@
-{ Interpreter = ./Interpreter.dhall, Template = ./Template.dhall }
diff --git a/gen/Deps/Sdk.dhall b/gen/Deps/Sdk.dhall
deleted file mode 100644
index 6cf6014..0000000
--- a/gen/Deps/Sdk.dhall
+++ /dev/null
@@ -1,3 +0,0 @@
-https://raw.githubusercontent.com/pgenie-io/gen-sdk/v0.11.0/dhall/package.dhall
-  sha256:8d43544ecb0e612406af3133bdbca51138c704a77a5a29ef62fe034d0e77a3a6
-  as Source
diff --git a/gen/Deps/package.dhall b/gen/Deps/package.dhall
deleted file mode 100644
index b395cd9..0000000
--- a/gen/Deps/package.dhall
+++ /dev/null
@@ -1,4 +0,0 @@
-{ Sdk = ./Sdk.dhall
-, Lude = ./Lude.dhall
-, Prelude = ./Prelude.dhall
-}
diff --git a/gen/Gen.dhall b/gen/Gen.dhall
deleted file mode 100644
index 9cb87fb..0000000
--- a/gen/Gen.dhall
+++ /dev/null
@@ -1,3 +0,0 @@
-let Sdk = ./Deps/Sdk.dhall
-
-in  Sdk.module ./Config.dhall ./compile.dhall
diff --git a/gen/compile.dhall b/gen/compile.dhall
deleted file mode 100644
index cd12642..0000000
--- a/gen/compile.dhall
+++ /dev/null
@@ -1,67 +0,0 @@
-let Deps = ./Deps/package.dhall
-
-let Model = Deps.Sdk.Project
-
-let Prelude = Deps.Prelude
-
-let Config = ./Config.dhall
-
-let OnUnsupported = ./Structures/OnUnsupported.dhall
-
-let ProjectInterpreter = ./Interpreters/Project.dhall
-
--- Entry point handed to gen-sdk's module. `config` and each of its fields are
--- Optional, so a project may omit the whole config block or any subset of its
--- keys; `defaults` collects every fallback in one place (packageName from the
--- project name in kebab case, emitSync off, onUnsupported Fail), so a future
--- knob's default is added here alongside the others. The async surface is
--- always emitted; emitSync adds the sync mirror.
-in  \(config : Optional Config) ->
-    \(project : Model.Project) ->
-      let defaults =
-            { packageName = project.name.inKebabCase
-            , emitSync = False
-            , onUnsupported = OnUnsupported.Mode.Fail
-            }
-
-      let packageName =
-            Prelude.Optional.fold
-              Config
-              config
-              Text
-              (\(c : Config) ->
-                Prelude.Optional.fold Text c.packageName Text (\(t : Text) -> t) defaults.packageName
-              )
-              defaults.packageName
-
-      let emitSync =
-            Prelude.Optional.fold
-              Config
-              config
-              Bool
-              (\(c : Config) ->
-                Prelude.Optional.fold Bool c.emitSync Bool (\(b : Bool) -> b) defaults.emitSync
-              )
-              defaults.emitSync
-
-      let onUnsupported =
-            Prelude.Optional.fold
-              Config
-              config
-              OnUnsupported.Mode
-              ( \(c : Config) ->
-                  Prelude.Optional.fold
-                    OnUnsupported.Mode
-                    c.onUnsupported
-                    OnUnsupported.Mode
-                    (\(m : OnUnsupported.Mode) -> m)
-                    defaults.onUnsupported
-              )
-              defaults.onUnsupported
-
-      let importName = Prelude.Text.replace "-" "_" packageName
-
-      let interpreterConfig =
-            { packageName, importName, emitSync, onUnsupported }
-
-      in  ProjectInterpreter.run interpreterConfig project
diff --git a/mise.toml b/mise.toml
index 040920b..68903bf 100644
--- a/mise.toml
+++ b/mise.toml
@@ -35,10 +35,10 @@ run = "bench/generate.sh without"
 # Regenerates only the "python" artifact: a full 7-artifact generate peaks at
 # ~31 GB RSS (memory goes to normalizing the generator closure per artifact,
 # see ci.yml), a single-artifact one at ~10 GB. The temp copy guarantees a
-# fresh resolve of the working-tree gen/ (no stale freeze) and keeps pgn's
+# fresh resolve of the working-tree src/ (no stale freeze) and keeps pgn's
 # scratch files out of the repo.
 [tasks.golden]
-description = "Refresh tests/golden from the working-tree gen/ (single-artifact run)"
+description = "Refresh tests/golden from the working-tree src/ (single-artifact run)"
 run = '''
 #!/usr/bin/env bash
 set -euo pipefail
@@ -48,14 +48,14 @@ trap 'rm -rf "$tmp"' EXIT
 cp -R "$root/tests/fixture-project/." "$tmp/fixture"
 rm -f "$tmp/fixture/freeze1.pgn.yaml"
 rm -rf "$tmp/fixture/artifacts"
-python3 - "$tmp/fixture/project1.pgn.yaml" "$root/gen/Gen.dhall" <<'EOF'
+python3 - "$tmp/fixture/project1.pgn.yaml" "$root/src/package.dhall" <<'EOF'
 import sys
 from pathlib import Path
 
 p = Path(sys.argv[1])
 head, sep, _ = p.read_text().partition("  # The variants below")
 assert sep, "variants marker not found in project1.pgn.yaml"
-_ = p.write_text(head.rstrip().replace("../../gen/Gen.dhall", sys.argv[2]) + "\n")
+_ = p.write_text(head.rstrip().replace("../../src/package.dhall", sys.argv[2]) + "\n")
 EOF
 cd "$tmp/fixture"
 pgn --database-url "${PGN_TEST_DATABASE_URL:-postgresql://postgres:postgres@localhost:5432/postgres?sslmode=disable}" generate
diff --git a/gen/Config.dhall b/src/Config.dhall
similarity index 89%
rename from gen/Config.dhall
rename to src/Config.dhall
index 7ec1fe6..1377127 100644
--- a/gen/Config.dhall
+++ b/src/Config.dhall
@@ -5,7 +5,7 @@
 -- unsupported statement/type and its dependents, with a warning) when a query
 -- or custom type hits a PG shape the generator cannot render; see
 -- Structures/OnUnsupported.dhall. All fields are Optional so a project may omit
--- the whole config block or any subset of its keys; compile.dhall supplies the
+-- the whole config block or any subset of its keys; Interpret.dhall supplies the
 -- defaults.
 let OnUnsupported = ./Structures/OnUnsupported.dhall
 
diff --git a/src/Deps/Contract.dhall b/src/Deps/Contract.dhall
new file mode 100644
index 0000000..ea9e805
--- /dev/null
+++ b/src/Deps/Contract.dhall
@@ -0,0 +1,2 @@
+https://raw.githubusercontent.com/pgenie-io/gen-contract/v4.0.1/src/package.dhall
+  sha256:4a130ba7fbaa152a776babbb1bf2994a4833931ca76bde9bf6930d354225651e
diff --git a/gen/Deps/Lude.dhall b/src/Deps/Lude.dhall
similarity index 100%
rename from gen/Deps/Lude.dhall
rename to src/Deps/Lude.dhall
diff --git a/gen/Deps/Prelude.dhall b/src/Deps/Prelude.dhall
similarity index 100%
rename from gen/Deps/Prelude.dhall
rename to src/Deps/Prelude.dhall
diff --git a/src/Deps/Sdk.dhall b/src/Deps/Sdk.dhall
new file mode 100644
index 0000000..5602c43
--- /dev/null
+++ b/src/Deps/Sdk.dhall
@@ -0,0 +1,3 @@
+https://raw.githubusercontent.com/pgenie-io/gen-sdk/v2.0.0/src/package.dhall
+  sha256:b9def6ab1179bc4aaae7fc6e91977f094f75934cd5755175c294a9e97ca71b15
+  as Source
diff --git a/src/Interpret.dhall b/src/Interpret.dhall
new file mode 100644
index 0000000..de4642f
--- /dev/null
+++ b/src/Interpret.dhall
@@ -0,0 +1,54 @@
+let Contract = ./Deps/Contract.dhall
+
+let Prelude = ./Deps/Prelude.dhall
+
+let Config = ./Config.dhall
+
+let OnUnsupported = ./Structures/OnUnsupported.dhall
+
+let ProjectInterpreter = ./Interpreters/Project.dhall
+
+-- Entry point handed to gen-sdk's Sdk.Sigs.generator as `interpret`. Each
+-- field of Config is independently Optional, so a project may omit the
+-- whole config block (Sdk.Sigs.generator substitutes an all-None
+-- defaultConfig, see package.dhall) or any subset of its keys; `defaults`
+-- collects every fallback in one place (packageName from the project name in
+-- kebab case, emitSync off, onUnsupported Fail). The async surface is always
+-- emitted; emitSync adds the sync mirror.
+in  \(config : Config) ->
+    \(project : Contract.Project) ->
+      let defaults =
+            { packageName = project.name.inKebabCase
+            , emitSync = False
+            , onUnsupported = OnUnsupported.Mode.Fail
+            }
+
+      let packageName =
+            Prelude.Optional.fold
+              Text
+              config.packageName
+              Text
+              (\(t : Text) -> t)
+              defaults.packageName
+
+      let emitSync =
+            Prelude.Optional.fold
+              Bool
+              config.emitSync
+              Bool
+              (\(b : Bool) -> b)
+              defaults.emitSync
+
+      let onUnsupported =
+            Prelude.Optional.fold
+              OnUnsupported.Mode
+              config.onUnsupported
+              OnUnsupported.Mode
+              (\(m : OnUnsupported.Mode) -> m)
+              defaults.onUnsupported
+
+      let importName = Prelude.Text.replace "-" "_" packageName
+
+      let interpreterConfig = { packageName, importName, emitSync, onUnsupported }
+
+      in  ProjectInterpreter.run interpreterConfig project
diff --git a/gen/Interpreters/CustomType.dhall b/src/Interpreters/CustomType.dhall
similarity index 94%
rename from gen/Interpreters/CustomType.dhall
rename to src/Interpreters/CustomType.dhall
index 7927f0a..676f9ab 100644
--- a/gen/Interpreters/CustomType.dhall
+++ b/src/Interpreters/CustomType.dhall
@@ -1,16 +1,16 @@
-let Deps = ../Deps/package.dhall
+let Lude = ../Deps/Lude.dhall
 
-let ImportSet = ../Structures/ImportSet.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let CustomKind = ../Structures/CustomKind.dhall
+let Model = ../Deps/Contract.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let Sdk = ../Deps/Sdk.dhall
 
-let Lude = Deps.Lude
+let ImportSet = ../Structures/ImportSet.dhall
 
-let Prelude = Deps.Prelude
+let CustomKind = ../Structures/CustomKind.dhall
 
-let Model = Deps.Sdk.Project
+let OnUnsupported = ../Structures/OnUnsupported.dhall
 
 let MemberGen = ./Member.dhall
 
@@ -18,6 +18,13 @@ let EnumModule = ../Templates/EnumModule.dhall
 
 let CompositeModule = ../Templates/CompositeModule.dhall
 
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
+
 let Input = Model.CustomType
 
 let TypeKind = < Enum | Composite >
@@ -75,7 +82,7 @@ let renderExtraImports =
               )
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(input : Input) ->
         let typeName = input.name.inPascalCase
 
@@ -174,4 +181,4 @@ let run =
               }
               input.definition
 
-in  { Input, Output, TypeKind, run }
+in  Sdk.Sigs.interpreter Config Input Output run
diff --git a/gen/Interpreters/Member.dhall b/src/Interpreters/Member.dhall
similarity index 95%
rename from gen/Interpreters/Member.dhall
rename to src/Interpreters/Member.dhall
index 672dd18..8d2d27c 100644
--- a/gen/Interpreters/Member.dhall
+++ b/src/Interpreters/Member.dhall
@@ -1,4 +1,8 @@
-let Deps = ../Deps/package.dhall
+let Lude = ../Deps/Lude.dhall
+
+let Prelude = ../Deps/Prelude.dhall
+
+let Model = ../Deps/Contract.dhall
 
 let ImportSet = ../Structures/ImportSet.dhall
 
@@ -6,14 +10,17 @@ let CustomKind = ../Structures/CustomKind.dhall
 
 let PyIdent = ../Structures/PyIdent.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
-
-let Lude = Deps.Lude
-
-let Model = Deps.Sdk.Project
+let OnUnsupported = ../Structures/OnUnsupported.dhall
 
 let Value = ./Value.dhall
 
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
+
 let Input = Model.Member
 
 -- decodeExpr is a Dhall function: given the source expression (e.g. row["x"] or
@@ -29,7 +36,7 @@ let Output =
       }
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(lookup : CustomKind.Lookup) ->
       \(input : Input) ->
         -- Result-column / composite-field name becomes a dataclass field and decode
@@ -95,7 +102,7 @@ let run =
                       \(fields : List CustomKind.CompositeField) ->
                       \(src : Text) ->
                         let fieldTypes =
-                              Deps.Prelude.Text.concatMapSep
+                              Prelude.Text.concatMapSep
                                 ", "
                                 CustomKind.CompositeField
                                 (\(f : CustomKind.CompositeField) -> f.pyType)
@@ -120,7 +127,7 @@ let run =
                             , decodeExpr = passthroughDecode
                             }
                       , Custom =
-                          Deps.Prelude.Optional.fold
+                          Prelude.Optional.fold
                             Model.Name
                             value.scalar.customRef
                             (Lude.Compiled.Type Output)
@@ -235,6 +242,6 @@ let run =
 
         in  Lude.Compiled.flatMap Value.Output Output buildOutput compiledValue
 
-let Run = Algebra.Config -> CustomKind.Lookup -> Input -> Lude.Compiled.Type Output
+let Run = Config -> CustomKind.Lookup -> Input -> Lude.Compiled.Type Output
 
 in  { Input, Output, Run, run }
diff --git a/gen/Interpreters/ParamsMember.dhall b/src/Interpreters/ParamsMember.dhall
similarity index 93%
rename from gen/Interpreters/ParamsMember.dhall
rename to src/Interpreters/ParamsMember.dhall
index 47bef3f..2a4b469 100644
--- a/gen/Interpreters/ParamsMember.dhall
+++ b/src/Interpreters/ParamsMember.dhall
@@ -1,17 +1,24 @@
-let Deps = ../Deps/package.dhall
+let Lude = ../Deps/Lude.dhall
 
-let ImportSet = ../Structures/ImportSet.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let CustomKind = ../Structures/CustomKind.dhall
+let Model = ../Deps/Contract.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let ImportSet = ../Structures/ImportSet.dhall
 
-let Lude = Deps.Lude
+let CustomKind = ../Structures/CustomKind.dhall
 
-let Model = Deps.Sdk.Project
+let OnUnsupported = ../Structures/OnUnsupported.dhall
 
 let Value = ./Value.dhall
 
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
+
 let Input = Model.Member
 
 let PyIdent = ../Structures/PyIdent.dhall
@@ -192,7 +199,7 @@ let scalarIsJsonb =
 
 let valueIsArray =
       \(value : Model.Value) ->
-        Deps.Prelude.Optional.fold
+        Prelude.Optional.fold
           Model.ArraySettings
           value.arraySettings
           Bool
@@ -204,15 +211,15 @@ let valueIsArray =
 -- the two must not be collapsed.
 let isJsonbScalar =
       \(value : Model.Value) ->
-        Deps.Prelude.Bool.and
-          [ scalarIsJsonb value, Deps.Prelude.Bool.not (valueIsArray value) ]
+        Prelude.Bool.and
+          [ scalarIsJsonb value, Prelude.Bool.not (valueIsArray value) ]
 
 let isJsonScalar =
       \(value : Model.Value) ->
-        Deps.Prelude.Bool.and
+        Prelude.Bool.and
           [ scalarIsJson value
-          , Deps.Prelude.Bool.not (scalarIsJsonb value)
-          , Deps.Prelude.Bool.not (valueIsArray value)
+          , Prelude.Bool.not (scalarIsJsonb value)
+          , Prelude.Bool.not (valueIsArray value)
           ]
 
 -- A json/jsonb ARRAY param has no faithful psycopg bind (Jsonb wraps a scalar,
@@ -221,10 +228,10 @@ let isJsonScalar =
 -- in SQL is the supported route (the param then types as text[], not json[]).
 let isJsonArray =
       \(value : Model.Value) ->
-        Deps.Prelude.Bool.and [ scalarIsJson value, valueIsArray value ]
+        Prelude.Bool.and [ scalarIsJson value, valueIsArray value ]
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(lookup : CustomKind.Lookup) ->
       \(input : Input) ->
         let fieldName = pySafeName input.name.inSnakeCase
@@ -251,7 +258,7 @@ let run =
         let compositeBind =
               \(fields : List CustomKind.CompositeField) ->
                 let joinedFields =
-                      Deps.Prelude.Text.concatMapSep
+                      Prelude.Text.concatMapSep
                         ", "
                         CustomKind.CompositeField
                         ( \(f : CustomKind.CompositeField) ->
@@ -265,8 +272,8 @@ let run =
                 -- as a 1-tuple, so force it for exactly one field; concatMapSep
                 -- already inserts the internal comma for two or more.
                 let trailingComma =
-                      if    Deps.Prelude.Natural.equal
-                              ( Deps.Prelude.List.length
+                      if    Prelude.Natural.equal
+                              ( Prelude.List.length
                                   CustomKind.CompositeField
                                   fields
                               )
@@ -301,7 +308,7 @@ let run =
                         , needsJsonbImport
                         }
 
-                in  Deps.Prelude.Optional.fold
+                in  Prelude.Optional.fold
                       Model.Name
                       value.scalar.customRef
                       (Lude.Compiled.Type Output)
@@ -377,6 +384,6 @@ let run =
 
         in  Lude.Compiled.flatMap Value.Output Output buildOutput compiledValue
 
-let Run = Algebra.Config -> CustomKind.Lookup -> Input -> Lude.Compiled.Type Output
+let Run = Config -> CustomKind.Lookup -> Input -> Lude.Compiled.Type Output
 
 in  { Input, Output, Run, run }
diff --git a/gen/Interpreters/Primitive.dhall b/src/Interpreters/Primitive.dhall
similarity index 86%
rename from gen/Interpreters/Primitive.dhall
rename to src/Interpreters/Primitive.dhall
index 0e1cb70..052ef1b 100644
--- a/gen/Interpreters/Primitive.dhall
+++ b/src/Interpreters/Primitive.dhall
@@ -1,10 +1,19 @@
-let Deps = ../Deps/package.dhall
+let Lude = ../Deps/Lude.dhall
+
+let Model = ../Deps/Contract.dhall
+
+let Sdk = ../Deps/Sdk.dhall
 
 let ImportSet = ../Structures/ImportSet.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let OnUnsupported = ../Structures/OnUnsupported.dhall
 
-let Model = Deps.Sdk.Project
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
 
 let Input = Model.Primitive
 
@@ -13,16 +22,16 @@ let Output = { pyType : Text, imports : ImportSet.Type }
 let supported =
       \(pyType : Text) ->
       \(imports : ImportSet.Type) ->
-        Deps.Lude.Compiled.ok Output { pyType, imports }
+        Lude.Compiled.ok Output { pyType, imports }
 
 let unsupported =
       \(pgType : Text) ->
-        Deps.Lude.Compiled.report Output [ pgType ] "Unsupported type"
+        Lude.Compiled.report Output [ pgType ] "Unsupported type"
 
 let plain = \(pyType : Text) -> supported pyType ImportSet.empty
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(input : Input) ->
         merge
           { Bit = unsupported "bit"
@@ -89,4 +98,4 @@ let run =
           }
           input
 
-in  Algebra.module Input Output run
+in  Sdk.Sigs.interpreter Config Input Output run
diff --git a/gen/Interpreters/Project.dhall b/src/Interpreters/Project.dhall
similarity index 98%
rename from gen/Interpreters/Project.dhall
rename to src/Interpreters/Project.dhall
index d51438f..d4fa6d6 100644
--- a/gen/Interpreters/Project.dhall
+++ b/src/Interpreters/Project.dhall
@@ -1,12 +1,10 @@
-let Deps = ../Deps/package.dhall
+let Lude = ../Deps/Lude.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Lude = Deps.Lude
+let Model = ../Deps/Contract.dhall
 
-let Prelude = Deps.Prelude
-
-let Model = Deps.Sdk.Project
+let Sdk = ../Deps/Sdk.dhall
 
 let CustomKind = ../Structures/CustomKind.dhall
 
@@ -40,6 +38,13 @@ let OnUnsupported = ../Structures/OnUnsupported.dhall
 
 let Report = { path : List Text, message : Text }
 
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
+
 let Input = Model.Project
 
 let Output = Lude.Files.Type
@@ -67,7 +72,7 @@ let withHeader =
 -- Internal interpreter config (importName etc.) is only needed to satisfy
 -- Value.run's signature; rendering a composite field's pyType does not read it.
 let lookupConfig
-    : Algebra.Config
+    : Config
     = { packageName = ""
       , importName = ""
       , emitSync = False
@@ -175,7 +180,7 @@ let buildLookup =
           (\(_ : Model.Name) -> CustomKind.TypeKind.Absent)
 
 let combineOutputs =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(input : Input) ->
       \(queries : List QueryGen.Output) ->
       -- Already the post-Skip-filter surviving set (see `run`); equal to
@@ -430,7 +435,7 @@ let combineOutputs =
 let QueryCheck = { query : Model.Query, keep : Bool, warning : Optional Report }
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(input : Input) ->
         let skip = merge { Fail = False, Skip = True } config.onUnsupported
 
@@ -542,4 +547,4 @@ let run =
 
         in  Lude.Compiled.appendWarnings Output skipWarnings combined
 
-in  Algebra.module Input Output run
+in  Sdk.Sigs.interpreter Config Input Output run
diff --git a/gen/Interpreters/Query.dhall b/src/Interpreters/Query.dhall
similarity index 94%
rename from gen/Interpreters/Query.dhall
rename to src/Interpreters/Query.dhall
index b0e688d..cce3fcd 100644
--- a/gen/Interpreters/Query.dhall
+++ b/src/Interpreters/Query.dhall
@@ -1,6 +1,6 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let Lude = ../Deps/Lude.dhall
 
 let ImportSet = ../Structures/ImportSet.dhall
 
@@ -10,6 +10,8 @@ let PyIdent = ../Structures/PyIdent.dhall
 
 let Surface = ../Structures/Surface.dhall
 
+let OnUnsupported = ../Structures/OnUnsupported.dhall
+
 let RowsModule = ../Templates/RowsModule.dhall
 
 let ResultModule = ./Result.dhall
@@ -20,13 +22,16 @@ let ParamsMember = ./ParamsMember.dhall
 
 let StatementModule = ../Templates/StatementModule.dhall
 
-let Prelude = Deps.Prelude
-
-let Lude = Deps.Lude
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
 
 let Compiled = Lude.Compiled
 
-let Model = Deps.Sdk.Project
+let Model = ../Deps/Contract.dhall
 
 let Input = Model.Query
 
@@ -46,7 +51,7 @@ let Output =
       }
 
 let render =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(input : Input) ->
       \(result : ResultModule.Output) ->
       \(fragments : QueryFragmentsModule.Output) ->
@@ -131,7 +136,7 @@ let render =
             }
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(lookup : CustomKind.Lookup) ->
       \(input : Input) ->
         let rowClassName = input.name.inPascalCase ++ "Row"
diff --git a/gen/Interpreters/QueryFragments.dhall b/src/Interpreters/QueryFragments.dhall
similarity index 75%
rename from gen/Interpreters/QueryFragments.dhall
rename to src/Interpreters/QueryFragments.dhall
index 066bc75..7813900 100644
--- a/gen/Interpreters/QueryFragments.dhall
+++ b/src/Interpreters/QueryFragments.dhall
@@ -1,16 +1,21 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let Lude = ../Deps/Lude.dhall
 
-let Prelude = Deps.Prelude
+let Sdk = ../Deps/Sdk.dhall
 
-let Sdk = Deps.Sdk
+let Compiled = Lude.Compiled
 
-let Lude = Deps.Lude
+let Model = ../Deps/Contract.dhall
 
-let Compiled = Lude.Compiled
+let OnUnsupported = ../Structures/OnUnsupported.dhall
 
-let Model = Deps.Sdk.Project
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
 
 let Input = Model.QueryFragments
 
@@ -47,8 +52,8 @@ let renderSql
         Prelude.Text.concatMap Model.QueryFragment renderFragment fragments
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(input : Input) ->
         Compiled.ok Output { sqlLiteral = renderSql input }
 
-in  Algebra.module Input Output run
+in  Sdk.Sigs.interpreter Config Input Output run
diff --git a/gen/Interpreters/Result.dhall b/src/Interpreters/Result.dhall
similarity index 88%
rename from gen/Interpreters/Result.dhall
rename to src/Interpreters/Result.dhall
index a6638e3..5d652a0 100644
--- a/gen/Interpreters/Result.dhall
+++ b/src/Interpreters/Result.dhall
@@ -1,20 +1,25 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let Lude = ../Deps/Lude.dhall
+
+let Model = ../Deps/Contract.dhall
 
 let ImportSet = ../Structures/ImportSet.dhall
 
 let CustomKind = ../Structures/CustomKind.dhall
 
-let ResultColumns = ./ResultColumns.dhall
-
-let Prelude = Deps.Prelude
+let OnUnsupported = ../Structures/OnUnsupported.dhall
 
-let Lude = Deps.Lude
+let ResultColumns = ./ResultColumns.dhall
 
 let Compiled = Lude.Compiled
 
-let Model = Deps.Sdk.Project
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
 
 let Input = Model.Result
 
@@ -57,7 +62,7 @@ let cardinalityShape
           cardinality
 
 let rowsOutput =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(lookup : CustomKind.Lookup) ->
       \(rowClassName : Text) ->
       \(rows : Model.ResultRows) ->
@@ -84,7 +89,7 @@ let rowsOutput =
               (ResultColumns.run config lookup rowClassName columns)
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(lookup : CustomKind.Lookup) ->
       \(rowClassName : Text) ->
       \(input : Input) ->
diff --git a/gen/Interpreters/ResultColumns.dhall b/src/Interpreters/ResultColumns.dhall
similarity index 84%
rename from gen/Interpreters/ResultColumns.dhall
rename to src/Interpreters/ResultColumns.dhall
index ef550ec..e0bbfaa 100644
--- a/gen/Interpreters/ResultColumns.dhall
+++ b/src/Interpreters/ResultColumns.dhall
@@ -1,20 +1,25 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let Lude = ../Deps/Lude.dhall
+
+let Model = ../Deps/Contract.dhall
 
 let ImportSet = ../Structures/ImportSet.dhall
 
 let CustomKind = ../Structures/CustomKind.dhall
 
-let Member = ./Member.dhall
-
-let Prelude = Deps.Prelude
+let OnUnsupported = ../Structures/OnUnsupported.dhall
 
-let Lude = Deps.Lude
+let Member = ./Member.dhall
 
 let Compiled = Lude.Compiled
 
-let Model = Deps.Sdk.Project
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
 
 let Input = List Model.Member
 
@@ -53,7 +58,7 @@ let assemble
         }
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(lookup : CustomKind.Lookup) ->
       \(rowClassName : Text) ->
       \(input : Input) ->
diff --git a/gen/Interpreters/Scalar.dhall b/src/Interpreters/Scalar.dhall
similarity index 77%
rename from gen/Interpreters/Scalar.dhall
rename to src/Interpreters/Scalar.dhall
index b0eff70..63ec788 100644
--- a/gen/Interpreters/Scalar.dhall
+++ b/src/Interpreters/Scalar.dhall
@@ -1,15 +1,22 @@
-let Deps = ../Deps/package.dhall
+let Lude = ../Deps/Lude.dhall
 
-let ImportSet = ../Structures/ImportSet.dhall
+let Model = ../Deps/Contract.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let Sdk = ../Deps/Sdk.dhall
 
-let Lude = Deps.Lude
+let ImportSet = ../Structures/ImportSet.dhall
 
-let Model = Deps.Sdk.Project
+let OnUnsupported = ../Structures/OnUnsupported.dhall
 
 let Primitive = ./Primitive.dhall
 
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
+
 let Input = Model.Scalar
 
 -- Passthrough for primitives; Custom is opaque here. The enum-vs-composite
@@ -24,7 +31,7 @@ let Output =
       }
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(input : Input) ->
         merge
           { Primitive =
@@ -52,4 +59,4 @@ let run =
           }
           input
 
-in  Algebra.module Input Output run /\ { ScalarDecode }
+in  Sdk.Sigs.interpreter Config Input Output run /\ { ScalarDecode }
diff --git a/gen/Interpreters/Value.dhall b/src/Interpreters/Value.dhall
similarity index 80%
rename from gen/Interpreters/Value.dhall
rename to src/Interpreters/Value.dhall
index de69fd0..e1c8d6a 100644
--- a/gen/Interpreters/Value.dhall
+++ b/src/Interpreters/Value.dhall
@@ -1,17 +1,24 @@
-let Deps = ../Deps/package.dhall
+let Lude = ../Deps/Lude.dhall
 
-let ImportSet = ../Structures/ImportSet.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Interpreter.dhall
+let Model = ../Deps/Contract.dhall
 
-let Lude = Deps.Lude
+let Sdk = ../Deps/Sdk.dhall
 
-let Prelude = Deps.Prelude
+let ImportSet = ../Structures/ImportSet.dhall
 
-let Model = Deps.Sdk.Project
+let OnUnsupported = ../Structures/OnUnsupported.dhall
 
 let Scalar = ./Scalar.dhall
 
+let Config =
+      { packageName : Text
+      , importName : Text
+      , emitSync : Bool
+      , onUnsupported : OnUnsupported.Mode
+      }
+
 let Input = Model.Value
 
 let Output =
@@ -23,7 +30,7 @@ let Output =
       }
 
 let run =
-      \(config : Algebra.Config) ->
+      \(config : Config) ->
       \(input : Input) ->
         Lude.Compiled.map
           Scalar.Output
@@ -62,4 +69,4 @@ let run =
           )
           (Scalar.run config input.scalar)
 
-in  Algebra.module Input Output run
+in  Sdk.Sigs.interpreter Config Input Output run
diff --git a/gen/Structures/CustomKind.dhall b/src/Structures/CustomKind.dhall
similarity index 95%
rename from gen/Structures/CustomKind.dhall
rename to src/Structures/CustomKind.dhall
index 22d3031..f2c4a1b 100644
--- a/gen/Structures/CustomKind.dhall
+++ b/src/Structures/CustomKind.dhall
@@ -1,6 +1,4 @@
-let Deps = ../Deps/package.dhall
-
-let Model = Deps.Sdk.Project
+let Model = ../Deps/Contract.dhall
 
 -- A composite field as the decode/encode sites need it: the Python attribute
 -- name and the rendered Python type (already nullability-applied). Threaded so
diff --git a/gen/Structures/ImportSet.dhall b/src/Structures/ImportSet.dhall
similarity index 100%
rename from gen/Structures/ImportSet.dhall
rename to src/Structures/ImportSet.dhall
diff --git a/gen/Structures/OnUnsupported.dhall b/src/Structures/OnUnsupported.dhall
similarity index 100%
rename from gen/Structures/OnUnsupported.dhall
rename to src/Structures/OnUnsupported.dhall
diff --git a/gen/Structures/PyIdent.dhall b/src/Structures/PyIdent.dhall
similarity index 100%
rename from gen/Structures/PyIdent.dhall
rename to src/Structures/PyIdent.dhall
diff --git a/gen/Structures/Surface.dhall b/src/Structures/Surface.dhall
similarity index 100%
rename from gen/Structures/Surface.dhall
rename to src/Structures/Surface.dhall
diff --git a/gen/Templates/CompositeModule.dhall b/src/Templates/CompositeModule.dhall
similarity index 80%
rename from gen/Templates/CompositeModule.dhall
rename to src/Templates/CompositeModule.dhall
index 198c77d..b1ab3e0 100644
--- a/gen/Templates/CompositeModule.dhall
+++ b/src/Templates/CompositeModule.dhall
@@ -1,6 +1,6 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Template.dhall
+let Sdk = ../Deps/Sdk.dhall
 
 let Field = { fieldName : Text, fieldType : Text }
 
@@ -12,7 +12,7 @@ let Params = { typeName : Text, extraImports : List Text, fields : List Field }
 let run =
       \(params : Params) ->
         let fieldLines =
-              Deps.Prelude.Text.concatMapSep
+              Prelude.Text.concatMapSep
                 "\n"
                 Field
                 ( \(field : Field) ->
@@ -21,12 +21,12 @@ let run =
                 params.fields
 
         let imports =
-              if    Deps.Prelude.List.null Text params.extraImports
+              if    Prelude.List.null Text params.extraImports
               then  "from dataclasses import dataclass"
               else  ''
                     from dataclasses import dataclass
 
-                    ${Deps.Prelude.Text.concatSep "\n" params.extraImports}''
+                    ${Prelude.Text.concatSep "\n" params.extraImports}''
 
         in  ''
             ${imports}
@@ -43,4 +43,4 @@ let run =
             ${fieldLines}
             ''
 
-in  Algebra.module Params run /\ { Field }
+in  Sdk.Sigs.template Params run /\ { Field }
diff --git a/gen/Templates/CoreModule.dhall b/src/Templates/CoreModule.dhall
similarity index 95%
rename from gen/Templates/CoreModule.dhall
rename to src/Templates/CoreModule.dhall
index d3938c2..34a4943 100644
--- a/gen/Templates/CoreModule.dhall
+++ b/src/Templates/CoreModule.dhall
@@ -1,4 +1,4 @@
-let Algebra = ../Algebras/Template.dhall
+let Sdk = ../Deps/Sdk.dhall
 
 -- The surface-agnostic core of a generated package, emitted once at
 -- _generated/_core.py. It owns the names shared by every module and by both the
@@ -43,4 +43,4 @@ let content =
           )
       ''
 
-in  Algebra.module {} (\(_ : {}) -> content)
+in  Sdk.Sigs.template {} (\(_ : {}) -> content)
diff --git a/gen/Templates/EnumModule.dhall b/src/Templates/EnumModule.dhall
similarity index 68%
rename from gen/Templates/EnumModule.dhall
rename to src/Templates/EnumModule.dhall
index 7f82ebf..1ebf486 100644
--- a/gen/Templates/EnumModule.dhall
+++ b/src/Templates/EnumModule.dhall
@@ -1,6 +1,6 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Template.dhall
+let Sdk = ../Deps/Sdk.dhall
 
 let Variant = { memberName : Text, pgValue : Text }
 
@@ -16,18 +16,18 @@ let run =
         let escapeLabel
             : Text -> Text
             = \(raw : Text) ->
-                Deps.Prelude.Function.composeList
+                Prelude.Function.composeList
                   Text
-                  [ Deps.Prelude.Text.replace "\\" "\\\\"
-                  , Deps.Prelude.Text.replace "\r" "\\r"
-                  , Deps.Prelude.Text.replace "\n" "\\n"
-                  , Deps.Prelude.Text.replace "\t" "\\t"
-                  , Deps.Prelude.Text.replace "\"" "\\\""
+                  [ Prelude.Text.replace "\\" "\\\\"
+                  , Prelude.Text.replace "\r" "\\r"
+                  , Prelude.Text.replace "\n" "\\n"
+                  , Prelude.Text.replace "\t" "\\t"
+                  , Prelude.Text.replace "\"" "\\\""
                   ]
                   raw
 
         let memberLines =
-              Deps.Prelude.Text.concatMapSep
+              Prelude.Text.concatMapSep
                 "\n"
                 Variant
                 ( \(variant : Variant) ->
@@ -43,4 +43,4 @@ let run =
             ${memberLines}
             ''
 
-in  Algebra.module Params run /\ { Variant }
+in  Sdk.Sigs.template Params run /\ { Variant }
diff --git a/gen/Templates/FacadeModule.dhall b/src/Templates/FacadeModule.dhall
similarity index 96%
rename from gen/Templates/FacadeModule.dhall
rename to src/Templates/FacadeModule.dhall
index 2beb74c..18d6f2e 100644
--- a/gen/Templates/FacadeModule.dhall
+++ b/src/Templates/FacadeModule.dhall
@@ -1,8 +1,6 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Template.dhall
-
-let Prelude = Deps.Prelude
+let Sdk = ../Deps/Sdk.dhall
 
 -- A statement's public surface: the function and, when the query returns rows,
 -- its frozen Row dataclass. functionName doubles as the leaf module name.
@@ -126,4 +124,4 @@ let run =
             ${allEntries}]
             ''
 
-in  Algebra.module Params run /\ { StatementExport, TypeExport }
+in  Sdk.Sigs.template Params run /\ { StatementExport, TypeExport }
diff --git a/gen/Templates/InitModule.dhall b/src/Templates/InitModule.dhall
similarity index 87%
rename from gen/Templates/InitModule.dhall
rename to src/Templates/InitModule.dhall
index f609ed6..cf5fc9f 100644
--- a/gen/Templates/InitModule.dhall
+++ b/src/Templates/InitModule.dhall
@@ -1,4 +1,4 @@
-let Algebra = ../Algebras/Template.dhall
+let Sdk = ../Deps/Sdk.dhall
 
 -- A minimal package __init__.py: a module docstring plus an empty __all__.
 -- Used for the _generated subpackage root and the statements subpackage. The
@@ -15,4 +15,4 @@ let render =
         __all__: list[str] = []
         ''
 
-in  Algebra.module Params render
+in  Sdk.Sigs.template Params render
diff --git a/gen/Templates/RegisterModule.dhall b/src/Templates/RegisterModule.dhall
similarity index 96%
rename from gen/Templates/RegisterModule.dhall
rename to src/Templates/RegisterModule.dhall
index ec6886b..cc94bfb 100644
--- a/gen/Templates/RegisterModule.dhall
+++ b/src/Templates/RegisterModule.dhall
@@ -1,11 +1,9 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Template.dhall
+let Sdk = ../Deps/Sdk.dhall
 
 let Surface = ../Structures/Surface.dhall
 
-let Prelude = Deps.Prelude
-
 -- Per-connection type registration, emitted once per surface. psycopg decodes an
 -- unregistered composite as a text string; registering its CompositeInfo makes
 -- it decode to a namedtuple, which the generated decode then splats into the
@@ -96,4 +94,4 @@ let run =
 
         in  Prelude.Text.concatSep "\n" allLines ++ "\n"
 
-in  Algebra.module Params run
+in  Sdk.Sigs.template Params run
diff --git a/gen/Templates/RowsModule.dhall b/src/Templates/RowsModule.dhall
similarity index 94%
rename from gen/Templates/RowsModule.dhall
rename to src/Templates/RowsModule.dhall
index 0107fa2..18da31b 100644
--- a/gen/Templates/RowsModule.dhall
+++ b/src/Templates/RowsModule.dhall
@@ -1,10 +1,10 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Template.dhall
+let Lude = ../Deps/Lude.dhall
 
-let ImportSet = ../Structures/ImportSet.dhall
+let Sdk = ../Deps/Sdk.dhall
 
-let Prelude = Deps.Prelude
+let ImportSet = ../Structures/ImportSet.dhall
 
 -- The shared row module: every query's frozen Row dataclass and its decode
 -- function live here once, so the async and sync statement modules import the
@@ -25,7 +25,7 @@ let indentAll
       \(text : Text) ->
         let pad = Prelude.Text.replicate n " "
 
-        in  pad ++ Deps.Lude.Text.indentNonEmpty n text
+        in  pad ++ Lude.Text.indentNonEmpty n text
 
 let importLineIf
     : Bool -> Text -> List Text
@@ -118,4 +118,4 @@ let run =
         ++  Prelude.Text.concatMapSep "\n\n\n" RowDef renderRow params.rows
         ++  "\n"
 
-in  Algebra.module Params run /\ { RowDef }
+in  Sdk.Sigs.template Params run /\ { RowDef }
diff --git a/gen/Templates/RuntimeModule.dhall b/src/Templates/RuntimeModule.dhall
similarity index 98%
rename from gen/Templates/RuntimeModule.dhall
rename to src/Templates/RuntimeModule.dhall
index ddaf53a..baa56bc 100644
--- a/gen/Templates/RuntimeModule.dhall
+++ b/src/Templates/RuntimeModule.dhall
@@ -1,4 +1,4 @@
-let Algebra = ../Algebras/Template.dhall
+let Sdk = ../Deps/Sdk.dhall
 
 -- The fixed _runtime.py body, emitted once per generated package. No per-query
 -- customization. Mirrors DESIGN section 3 with two strict-clean adjustments the
@@ -160,5 +160,5 @@ let syncContent =
               _ = cur.execute(sql, params)
       ''
 
-in    Algebra.module {} (\(_ : {}) -> content)
+in    Sdk.Sigs.template {} (\(_ : {}) -> content)
     /\ { runSync = \(_ : {}) -> syncContent }
diff --git a/gen/Templates/StatementModule.dhall b/src/Templates/StatementModule.dhall
similarity index 97%
rename from gen/Templates/StatementModule.dhall
rename to src/Templates/StatementModule.dhall
index f717aa7..f2a6f61 100644
--- a/gen/Templates/StatementModule.dhall
+++ b/src/Templates/StatementModule.dhall
@@ -1,13 +1,13 @@
-let Algebra = ../Algebras/Template.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Deps = ../Deps/package.dhall
+let Lude = ../Deps/Lude.dhall
+
+let Sdk = ../Deps/Sdk.dhall
 
 let ImportSet = ../Structures/ImportSet.dhall
 
 let Surface = ../Structures/Surface.dhall
 
-let Prelude = Deps.Prelude
-
 -- Prefix every line (including the first) with `n` spaces, leaving blank lines
 -- untouched so trailing whitespace never appears.
 let indentAll
@@ -16,7 +16,7 @@ let indentAll
       \(text : Text) ->
         let pad = Prelude.Text.replicate n " "
 
-        in  pad ++ Deps.Lude.Text.indentNonEmpty n text
+        in  pad ++ Lude.Text.indentNonEmpty n text
 
 -- A statement module is the thin per-surface I/O wrapper: it imports its Row
 -- dataclass and decode function from the shared `_rows` module and renders one
@@ -187,7 +187,7 @@ let renderCall
             then  "return ${await}${params.helperName}(conn, _SQL, params, ${params.decodeName})"
             else  "return ${await}${params.helperName}(conn, _SQL, params)"
 
-in  Algebra.module
+in  Sdk.Sigs.template
       Params
       ( \(params : Params) ->
               renderImports params
diff --git a/gen/Templates/TypesInit.dhall b/src/Templates/TypesInit.dhall
similarity index 73%
rename from gen/Templates/TypesInit.dhall
rename to src/Templates/TypesInit.dhall
index 7583526..3182085 100644
--- a/gen/Templates/TypesInit.dhall
+++ b/src/Templates/TypesInit.dhall
@@ -1,6 +1,6 @@
-let Deps = ../Deps/package.dhall
+let Prelude = ../Deps/Prelude.dhall
 
-let Algebra = ../Algebras/Template.dhall
+let Sdk = ../Deps/Sdk.dhall
 
 let Export = { moduleName : Text, typeName : Text }
 
@@ -9,7 +9,7 @@ let Params = { exports : List Export }
 let run =
       \(params : Params) ->
         let exportLines =
-              Deps.Prelude.Text.concatMapSep
+              Prelude.Text.concatMapSep
                 "\n"
                 Export
                 ( \(export : Export) ->
@@ -21,4 +21,4 @@ let run =
             ${exportLines}
             ''
 
-in  Algebra.module Params run /\ { Export }
+in  Sdk.Sigs.template Params run /\ { Export }
diff --git a/src/package.dhall b/src/package.dhall
new file mode 100644
index 0000000..3d07cf7
--- /dev/null
+++ b/src/package.dhall
@@ -0,0 +1,16 @@
+let Sdk = ./Deps/Sdk.dhall
+
+let OnUnsupported = ./Structures/OnUnsupported.dhall
+
+let Config = ./Config.dhall
+
+let Config/default
+    : Config
+    = { packageName = None Text
+      , emitSync = None Bool
+      , onUnsupported = None OnUnsupported.Mode
+      }
+
+let interpret = ./Interpret.dhall
+
+in  Sdk.Sigs.generator Config Config/default interpret
diff --git a/tests/_harness.py b/tests/_harness.py
index 037ac41..9e5ffbd 100644
--- a/tests/_harness.py
+++ b/tests/_harness.py
@@ -23,7 +23,7 @@
 DEFAULT_MAX_RSS_GB = 40.0
 
 HERE = Path(__file__).resolve().parent
-GEN_DIR = HERE.parent / "gen"
+SRC_DIR = HERE.parent / "src"
 FIXTURE_PROJECT = HERE / "fixture-project"
 GOLDEN_DIR = HERE / "golden"
 
diff --git a/tests/conftest.py b/tests/conftest.py
index d0ccc23..5bac571 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -15,9 +15,9 @@
 
 from tests._harness import (
     FIXTURE_PROJECT,
-    GEN_DIR,
     GOLDEN_DIR,
     HERE,
+    SRC_DIR,
     admin_database_url,
     effective_database_name,
     run_pgn,
@@ -67,15 +67,15 @@ def fixture_copy(tmp_path: Path) -> Path:
 def generated_tree(pgn_bin: str, pgn_admin_url: str, tmp_path_factory: pytest.TempPathFactory) -> Path:
     """Generate the fixture client once and return its artifacts/python dir.
 
-    The generator path in project1.pgn.yaml is `../../gen/Gen.dhall`,
+    The generator path in project1.pgn.yaml is `../../src/package.dhall`,
     relative to the fixture project. To keep it resolvable the copy mirrors the
-    real layout: `<tmp>/gen` and `<tmp>/tests/fixture-project`. The freeze
+    real layout: `<tmp>/src` and `<tmp>/tests/fixture-project`. The freeze
     file is dropped so pgn re-resolves the working-tree generator instead of a
-    cached hash (a stale freeze makes pgn ignore gen/ edits and silently
+    cached hash (a stale freeze makes pgn ignore src/ edits and silently
     emit the old output).
     """
     root = tmp_path_factory.mktemp("pygen")
-    _ = shutil.copytree(GEN_DIR, root / "gen")
+    _ = shutil.copytree(SRC_DIR, root / "src")
     project = shutil.copytree(FIXTURE_PROJECT, root / "tests" / "fixture-project")
     (project / "freeze1.pgn.yaml").unlink(missing_ok=True)
     shutil.rmtree(project / "artifacts", ignore_errors=True)
diff --git a/tests/fixture-project/project1.pgn.yaml b/tests/fixture-project/project1.pgn.yaml
index f6bec82..ff75999 100644
--- a/tests/fixture-project/project1.pgn.yaml
+++ b/tests/fixture-project/project1.pgn.yaml
@@ -4,7 +4,7 @@ version: 0.0.0
 postgres: 18
 artifacts:
   python:
-    gen: ../../gen/Gen.dhall
+    gen: ../../src/package.dhall
     config:
       packageName: specimen-client
       emitSync: true
@@ -12,25 +12,25 @@ artifacts:
   # Optional Config knobs (undocumented by pgn itself); see
   # tests/test_config_variants.py for the assertions.
   python-name-only:
-    gen: ../../gen/Gen.dhall
+    gen: ../../src/package.dhall
     config:
       packageName: name-only-client
   python-sync-only:
-    gen: ../../gen/Gen.dhall
+    gen: ../../src/package.dhall
     config:
       emitSync: true
   python-empty:
-    gen: ../../gen/Gen.dhall
+    gen: ../../src/package.dhall
     config: {}
   python-bare:
-    gen: ../../gen/Gen.dhall
+    gen: ../../src/package.dhall
   python-unknown-key:
-    gen: ../../gen/Gen.dhall
+    gen: ../../src/package.dhall
     config:
       packageName: unknown-key-client
       bogusField: 1
   python-null:
-    gen: ../../gen/Gen.dhall
+    gen: ../../src/package.dhall
     config:
       packageName: null-client
       emitSync: null
diff --git a/tests/test_unsupported_types.py b/tests/test_unsupported_types.py
index 9d99eab..642db87 100644
--- a/tests/test_unsupported_types.py
+++ b/tests/test_unsupported_types.py
@@ -24,14 +24,14 @@
 
 import pytest
 
-from tests._harness import FIXTURE_PROJECT, GEN_DIR, HERE, run_pgn
+from tests._harness import FIXTURE_PROJECT, HERE, SRC_DIR, run_pgn
 
 HARNESS_ROOT = HERE.parent
 
 
 def test_unsupported_pg_type_fails_loudly(pgn_bin: str, pgn_admin_url: str, tmp_path: Path) -> None:
     root = tmp_path / "pygen"
-    _ = shutil.copytree(GEN_DIR, root / "gen")
+    _ = shutil.copytree(SRC_DIR, root / "src")
     project = shutil.copytree(FIXTURE_PROJECT, root / "tests" / "fixture-project")
     (project / "freeze1.pgn.yaml").unlink(missing_ok=True)
     shutil.rmtree(project / "artifacts", ignore_errors=True)
@@ -51,7 +51,7 @@ def test_unsupported_pg_type_fails_loudly(pgn_bin: str, pgn_admin_url: str, tmp_
 
 def test_json_array_param_fails_loudly(pgn_bin: str, pgn_admin_url: str, tmp_path: Path) -> None:
     root = tmp_path / "pygen"
-    _ = shutil.copytree(GEN_DIR, root / "gen")
+    _ = shutil.copytree(SRC_DIR, root / "src")
     project = shutil.copytree(FIXTURE_PROJECT, root / "tests" / "fixture-project")
     (project / "freeze1.pgn.yaml").unlink(missing_ok=True)
     shutil.rmtree(project / "artifacts", ignore_errors=True)
@@ -66,7 +66,7 @@ def test_json_array_param_fails_loudly(pgn_bin: str, pgn_admin_url: str, tmp_pat
         "postgres: 18\n"
         "artifacts:\n"
         "  python:\n"
-        "    gen: ../../gen/Gen.dhall\n"
+        "    gen: ../../src/package.dhall\n"
         "    config:\n"
         "      onUnsupported: Fail\n"
     )
@@ -104,7 +104,7 @@ def test_skip_unsupported_drops_offending_units_and_cascades(
     golden package is held to.
     """
     root = tmp_path / "pygen"
-    _ = shutil.copytree(GEN_DIR, root / "gen")
+    _ = shutil.copytree(SRC_DIR, root / "src")
     project = shutil.copytree(FIXTURE_PROJECT, root / "tests" / "fixture-project")
     (project / "freeze1.pgn.yaml").unlink(missing_ok=True)
     shutil.rmtree(project / "artifacts", ignore_errors=True)
@@ -129,7 +129,7 @@ def test_skip_unsupported_drops_offending_units_and_cascades(
         "postgres: 18\n"
         "artifacts:\n"
         "  python:\n"
-        "    gen: ../../gen/Gen.dhall\n"
+        "    gen: ../../src/package.dhall\n"
         "    config:\n"
         "      onUnsupported: Skip\n"
     )