chore: import upstream snapshot with attribution

extension/platform/examples/.gitignore

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+audit-observer/audit-observer
+readonly-policy/readonly-policy

extension/platform/examples/README.md

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+# lark-cli plugin examples
+
+Runnable fork-and-blank-import examples that demonstrate the Plugin
+SDK in production-shape. Each subdirectory is a complete `main`
+package: `go build .` produces a working CLI.
+
+| Example | What it shows |
+| --- | --- |
+| [audit-observer](./audit-observer/) | Simplest possible plugin: one Observer matching every command, logs to stderr. |
+| [readonly-policy](./readonly-policy/) | Policy plugin: `Restrict()` with `MaxRisk=read`, demonstrates the `FailClosed` + `Restricts=true` auto-pairing. |
+
+All examples are built by CI (`make examples-build`) so they cannot
+silently drift from the SDK.

extension/platform/examples/audit-observer/README.md

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+# Example: audit observer
+
+The simplest possible lark-cli plugin: one After observer that logs
+every dispatched command to stderr (success or failure).
+
+## Build & run
+
+```sh
+cd extension/platform/examples/audit-observer
+go build -o audit-cli .
+./audit-cli config plugins show
+# {"plugins":[{"name":"audit", ...}], "total":1}
+
+./audit-cli api GET /open-apis/contact/v3/users/me
+# [audit] api ok            (on stderr)
+```
+
+## Key points
+
+- `platform.NewPlugin(...).MustBuild()` from `init()`. The blank
+  import of this package in `main.go` triggers `init()`.
+- `Observer(platform.After, ...)` runs **after** the command's RunE,
+  even on failure (Observers cannot prevent execution).
+- `FailOpen()` means: if Install ever fails, the binary logs a
+  warning and continues without this plugin. Right default for
+  audit-only plugins.

extension/platform/examples/audit-observer/main.go

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+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+// Command audit-observer is a runnable fork of lark-cli that logs
+// every dispatched command to stderr. Demonstrates the simplest
+// possible plugin: one After observer matching All commands.
+//
+// Build & run:
+//
+//	cd extension/platform/examples/audit-observer
+//	go build -o audit-cli .
+//	./audit-cli config plugins show     # see "audit" in the list
+//	./audit-cli api GET /open-apis/...  # observer logs to stderr
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/larksuite/cli/cmd"
+	"github.com/larksuite/cli/extension/platform"
+)
+
+func init() {
+	platform.Register(
+		platform.NewPlugin("audit", "0.1.0").
+			Observer(platform.After, "log", platform.All(),
+				func(ctx context.Context, inv platform.Invocation) {
+					path := inv.Cmd().Path()
+					if err := inv.Err(); err != nil {
+						fmt.Fprintf(os.Stderr, "[audit] %s FAILED: %v\n", path, err)
+					} else {
+						log.Printf("[audit] %s ok", path)
+					}
+				}).
+			FailOpen().
+			MustBuild())
+}
+
+func main() {
+	os.Exit(cmd.Execute())
+}

extension/platform/examples/readonly-policy/README.md

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+# Example: read-only policy
+
+A policy plugin that installs a `Rule` allowing only `docs/*` and
+`im/*` read commands. Any write command produces a structured
+`command_denied` envelope.
+
+## Build & run
+
+```sh
+cd extension/platform/examples/readonly-policy
+go build -o readonly-cli .
+
+./readonly-cli config policy show
+# {
+#   "source": "plugin",
+#   "source_name": "readonly",
+#   "denied_paths": N,
+#   "rule": {
+#     "name": "agent-readonly",
+#     "allow": ["docs/**", "im/**"],
+#     "deny": [],
+#     "max_risk": "read",
+#     "identities": [],
+#     "allow_unannotated": false
+#   }
+# }
+
+./readonly-cli docs +update --doc-token X --content Y
+# {"ok":false,"error":{
+#   "type":"command_denied",
+#   "detail":{
+#     "layer":"policy",
+#     "policy_source":"plugin:readonly",
+#     "rule_name":"agent-readonly",
+#     "reason_code":"write_not_allowed"
+#   }
+# }}
+
+./readonly-cli docs +fetch --doc-token X
+# Normal read response (assuming credentials)
+```
+
+## Key points
+
+- `Restrict(&Rule{...})` is the only call needed — the Builder
+  flips Capabilities to `Restricts=true, FailurePolicy=FailClosed`
+  automatically. A policy plugin that silently fails to install
+  would erase the security boundary, so FailClosed is enforced.
+- `MaxRisk: platform.RiskRead` rejects any command annotated
+  write / high-risk-write.
+- `AllowUnannotated` is left default (false): unannotated commands
+  are denied with `risk_not_annotated`. Set it to true if you need
+  a gradual-adoption window for the lark-cli main tree.
+
+## Caveats
+
+- A binary may have **only one** plugin calling `Restrict()`. Two
+  policy plugins is a deliberate `plugin_conflict` configuration
+  error.
+- This Rule shadows any `~/.lark-cli/policy.yml` — plugin Rule
+  wins per the resolver precedence.

extension/platform/examples/readonly-policy/main.go

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+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+// Command readonly-policy is a runnable fork of lark-cli that
+// installs a Rule permitting only docs/* and im/* read commands.
+// Any write command produces a structured command_denied envelope.
+//
+// Build & run:
+//
+//	cd extension/platform/examples/readonly-policy
+//	go build -o readonly-cli .
+//	./readonly-cli docs +update --doc-token X --content Y
+//	# {"ok":false,"error":{"type":"command_denied", ...}}
+//
+//	./readonly-cli config policy show
+//	# shows the active Rule with source=plugin:readonly
+package main
+
+import (
+	"os"
+
+	"github.com/larksuite/cli/cmd"
+	"github.com/larksuite/cli/extension/platform"
+)
+
+func init() {
+	platform.Register(
+		platform.NewPlugin("readonly", "0.1.0").
+			Restrict(&platform.Rule{
+				Name:        "agent-readonly",
+				Description: "Only read-class docs/im commands. Suitable for AI-agent sessions.",
+				Allow:       []string{"docs/**", "im/**"},
+				MaxRisk:     platform.RiskRead,
+				// AllowUnannotated stays default false (fail-closed):
+				// unannotated commands are denied, surfacing missing
+				// risk_level annotations early in adoption.
+			}).
+			MustBuild())
+	// Note: Restrict() implicitly sets Restricts=true and FailClosed.
+	// No need to call FailClosed() explicitly.
+}
+
+func main() {
+	os.Exit(cmd.Execute())
+}