refactor: replace Nix flake with mise

.github/dependabot.yaml

@@ -34,17 +34,3 @@ updates:
       - dependency-name: "*"
         update-types:
           - version-update:semver-patch
-
-  - package-ecosystem: nix
-    directory: "/"
-    schedule:
-      interval: "weekly"
-      time: "06:00"
-      timezone: "America/Chicago"
-    labels: []
-    commit-message:
-      prefix: "chore"
-    groups:
-      nix:
-        patterns:
-          - "*"

.github/workflows/ci.yaml

@@ -31,25 +31,14 @@ jobs:
           fetch-tags: true
           persist-credentials: false
 
-      - name: Setup Nix
-        uses: nixbuild/nix-quick-install-action@2c9db80fb984ceb1bcaa77cdda3fdf8cfba92035 # v34
-
-      - name: Cache Nix store
-        uses: nix-community/cache-nix-action@7df957e333c1e5da7721f60227dbba6d06080569 # v7.0.2
+      - name: Setup mise
+        uses: jdx/mise-action@1648a7812b9aeae629881980618f079932869151 # v4.0.1
         with:
-          primary-key: nix-acp-go-sdk-${{ runner.os }}-${{ hashFiles('**/*.nix', 'flake.lock') }}
-          restore-prefixes-first-match: nix-acp-go-sdk-${{ runner.os }}-
-          gc-max-store-size-linux: 2G
-          purge: true
-          purge-prefixes: nix-acp-go-sdk-${{ runner.os }}-
-          purge-created: 0
-          purge-primary-key: never
+          install: true
+          cache: true
 
       - name: Check formatting (treefmt)
-        run: nix develop .# --command treefmt --fail-on-change
+        run: mise exec -- make check
 
       - name: Make tests
-        run: nix develop .# --command make test
-
-      - name: Nix flake checks
-        run: nix flake check
+        run: mise exec -- make test

.gitignore

@@ -5,6 +5,6 @@
 .gocache
 .gopath
 
-# Nix files
-.envrc
-.direnv
+# mise
+mise.local.toml
+.mise.local.toml

AGENTS.md

@@ -9,12 +9,13 @@ Core SDK code lives at the repo root (`agent.go`, `client.go`, `connection.go`,
 - `go test ./...` exercises unit tests across packages.
 - `go run ./example/agent` and `go run ./example/client` provide quick manual validation of agent/client behavior.
 - `make test` runs `go test` and ensures all examples still build.
-- `make fmt` delegates to `nix fmt` so Go, Nix, and Markdown stay formatted consistently.
-- `nix flake check` validates the flake definition and linting hooks used in CI.
+- `make fmt` runs `treefmt` so Go and Markdown stay formatted consistently.
+- `make check` runs `treefmt --fail-on-change` plus the README guard used in CI.
+- `mise install` provisions the toolchain (Go, gopls, golangci-lint, treefmt, etc.); run it once after cloning.
 
 ## Coding Style & Naming Conventions
 
-Target Go 1.21 idioms: tabs for indentation, short receiver names, and CamelCase for exported symbols (`AgentLoader`), lowerCamelCase for unexported helpers. Prefer table-driven tests and keep files focused on a single protocol concern. Run `nix fmt` or `gofumpt -w .` to normalize spacing, imports, and composite literals before sending a change.
+Target Go 1.21 idioms: tabs for indentation, short receiver names, and CamelCase for exported symbols (`AgentLoader`), lowerCamelCase for unexported helpers. Prefer table-driven tests and keep files focused on a single protocol concern. Run `make fmt` or `gofumpt -w .` to normalize spacing, imports, and composite literals before sending a change.
 
 ## Testing Guidelines
 

Makefile

@@ -6,7 +6,7 @@ MDSH ?= mdsh
 
 version: README.md schema/meta.json schema/schema.json schema/meta.unstable.json schema/schema.unstable.json
 	cd cmd/generate && env -u GOPATH -u GOMODCACHE go run .
-	env -u GOPATH -u GOMODCACHE go run mvdan.cc/gofumpt@latest -w .
+	gofumpt -w .
 	touch $@
 	echo $(ACP_VERSION) > $@
 
@@ -49,21 +49,23 @@ schema/schema.unstable.json: schema/version
 		fi
 
 README.md: schema/version
-	@command -v $(MDSH) >/dev/null || { echo "mdsh not found; run 'nix develop' or install it." 1>&2; exit 1; }
+	@command -v $(MDSH) >/dev/null || { echo "mdsh not found; run 'mise install' or install it." 1>&2; exit 1; }
 	$(MDSH) --input README.md
 
-.PHONY: guard-readme
-guard-readme:
-	@command -v $(MDSH) >/dev/null || { echo "mdsh not found; run 'nix develop' or install it." 1>&2; exit 1; }
-	$(MDSH) --frozen --input README.md
-
 .PHONY: fmt
 fmt:
-	nix fmt
+	treefmt
 
+# treefmt runs mdsh + mdformat over the markdown, which keeps README.md
+# regenerated and in sync (replacing the old mdsh guard). mdsh and mdformat
+# disagree on the blank line after an mdsh directive: mdsh strips it, mdformat
+# re-adds it. The net result is a no-op (README is a fixpoint of the pair), but
+# that intermediate churn trips treefmt's own --fail-on-change. So we format in
+# place and let git confirm there's no net drift instead.
 .PHONY: check
-check: guard-readme
-	nix flake check
+check:
+	treefmt
+	git diff --exit-code
 
 .PHONY: test
 test: $(GO_FILES)

RELEASING.md

@@ -7,11 +7,10 @@ code, helper APIs, and library version remain in sync.
 
 ## Prerequisites
 
-- Go 1.21 or newer.
 - `make`, `curl`, and `git` in your `PATH`.
-- Nix is required for `make fmt` and `make check` (they invoke `nix fmt` and
-  `nix flake check`). Use `nix develop` or an equivalent environment before
-  running these targets.
+- [mise](https://mise.jdx.dev) for the toolchain. Run `mise install` once to
+  provision Go, `treefmt`, and the formatters/linters that `make fmt` and
+  `make check` invoke.
 - The repository must have an Actions secret named `ANTHROPIC_API_KEY` so the
   release-notes workflow can update GitHub Release bodies after publication.