diff --git a/.ai/instructions.md b/.ai/instructions.md
index df8edc83..10d74571 100644
--- a/.ai/instructions.md
+++ b/.ai/instructions.md
@@ -92,3 +92,4 @@ Reference these files for scaffolding new code:
 - `.ai/skills/prompt.md` — Prompts class conventions; simple / standard / delegation / wizard variants
 - `.ai/skills/service.md` — Infrastructure Service conventions; SDK controller / axios-auth / axios-stateless variants
 - `.ai/skills/value-object.md` — Value object (rich class) conventions; encapsulation, boundary unwrapping, composition rules
+- `.ai/skills/contribution-guide.md` — Contribution workflow: branching from `dev`, local debugging/packaging, README updates, releasing the CLI and Platform SDK, NPM tagging
diff --git a/.ai/skills/contribution-guide.md b/.ai/skills/contribution-guide.md
new file mode 100644
index 00000000..934aab42
--- /dev/null
+++ b/.ai/skills/contribution-guide.md
@@ -0,0 +1,85 @@
+# Contribution Guide
+
+Please create your feature branch from the `dev` branch and add your changes. It is recommended to delete the local copy of the `dev` branch (if you have one) and pull the latest remote copy whenever you create your feature branch, this is needed because the `dev` branch is not a long-running branch and is deleted whenever we squash-and-merge to the release branch i.e. the `beta` branch.
+
+```
+Note: At the time of writing this Wiki, the CLI follows the `beta` release branch whereas the SDK follows the `alpha` release branch.
+```
+
+## Debugging the CLI Locally
+
+The `.vscode/launch.json` file serves as your entry point to debugging the CLI locally. Add the command + flags you want to debug in the `"args"` of the `"configurations"` section and press the F5 key to start debugging in VS Code.
+
+If you want to switch to the dev environment of the Platform API, add the `"env"` property to the `"configurations"` section as follows:
+
+```json
+"env": {
+   "NODE_TLS_REJECT_UNAUTHORIZED": "0",
+   "APIMATIC_BASE_URL": "https://app.dev.apimatic.io/api;https://auth.dev.apimatic.io;https://api.package-publishing.dev.apimatic.io/api"
+},
+```
+
+If you're looking to run the CLI on dev environment, just set the `APIMATIC_BASE_URL` in your environment variables as mentioned above.
+
+## Installing the Packaged CLI Locally
+
+1. Run `pnpm install` and `pnpm run build` after making your changes.
+2. Run `pnpm pack` to package the CLI, this will create a tar file in the repo.
+3. Uninstall any existing installations by running `pnpm remove -g @apimatic/cli`.
+4. Install the locally packaged CLI by running `pnpm add -g <file-name-of-tar-file>`.
+
+## Updating the README
+
+Whenever you add a new command or change the descriptions, flags, examples etc. properties within an existing command, remember to update the README using the command `oclif readme`. You need to install the `oclif` package first or run it on-demand by using the command `pnpm dlx oclif readme`. By default, this will generate the README changes automatically under the `<!-- usage -->` and `<!-- commands -->` comments in the README file.
+
+## Releasing the CLI
+
+1. Get your changes in your feature branch merged to the `dev` branch first.
+2. Create a release PR targeting the `beta` branch from the `dev` branch.
+3. *⚠️IMPORTANT⚠️* Before you can merge the `dev` branch to the `beta` branch, you must ask someone from the platform team to disable branch protection on the repo. We are using `semantic-release` package in our github action for releasing & publishing the CLI to NPM, and we have a limitation where `semantic-release` needs to create and push a commit to the `beta` branch right after release and create a tag for it. If branch protection is disabled, this step gets skipped and the release is incomplete.
+4. Squash-and-merge your changes and verify the release github action succeeds.
+
+## Updating the Latest Version on NPM for CLI after Release
+
+Before you can tag the released version as the `latest` version on NPM, you need an auth token to authenticate with NPM. You will also need to be added to the `apimatic` organisation on NPM. Contact someone from the Platform team if you are unclear about these steps.
+
+1. Switch to the `beta` branch and pull the latest changes after the release.
+2. Update the `.npmrc` file to add the line `//registry.npmjs.org/:_authToken=<your-npm-auth-token>`. *⚠️DO NOT COMMIT THE AUTH TOKEN TO THE REPOSITORY⚠️*
+3. Run the command `npm dist-tag add @apimatic/cli@<version-to-tag> latest`. Replace the `<version-to-tag>` placeholder with the actual version to tag as the latest, for e.g. `1.1.0-beta.10`.
+
+## Updating the Platform SDK
+
+Whenever you make any changes in the Platform API i.e. `apimatic-io` that are required in the CLI, like adding/updating an endpoint, you will need to update the Platform API's SDK by following these steps:
+
+1. Update the Platform API spec in the [`apimatic-docs`](https://github.com/apimatic/apimatic-docs/tree/v3-master/src/apimatic-sdk-docs) repo.
+2. Rename the `platform-sdk-generation-build.json` file to use it as your `APIMATIC-BUILD.json` file.
+3. Generate the SDK for the build using the `apimatic sdk generate` command in `typescript`.
+4. Create a feature branch in the [`apimatic-sdk-for-js`](https://github.com/apimatic/apimatic-sdk-for-js) repo. It is recommended to delete the local copy of the `dev` branch (if you have one) and pull the latest remote copy whenever you create your feature branch, this is needed because the `dev` branch is not a long-running branch and is deleted whenever we squash-and-merge to the release branch i.e. the `alpha` branch.
+5. Copy the contents of the generated SDK to your feature branch. Ensure that the `package.json` does not contain any unintended changes, reach out to someone from the platform team if you are unsure.
+6. Commit your changes and create a PR for merging your feature branch to the `dev` branch.
+
+## Testing the Updated SDK Changes with the CLI Locally
+
+1. Run `pnpm install` and `pnpm run build` in the SDK repo.
+2. Package the SDK using the command `pnpm pack`. It is highly recommended to change the version in the `package.json` and set it to something like `0.2.0-alpha.5-test` with the word `test` appended to the end and the version incremented by one (usually the patch version is incremented in MAJOR.MINOR.PATCH).
+3. Copy package tar file to the CLI repo where you have your feature branch open.
+4. Update the `package.json` `"dependencies"` section, set the `"@apimatic/sdk": "file:apimatic-sdk-0.2.0-alpha.5-test.tgz"`, with the correct tar file name.
+5. Update the `package.json` `"files"` property and add a new value in the array like `"/apimatic-sdk-0.2.0-alpha.5-test.tgz"`.
+6. Run `pnpm install` and `pnpm run build`, and you can locally debug to verify your changes. Feel free to run `pnpm pack` in case you want to test the packaged CLI.
+7. The packaged CLI build will contain the updated SDK.
+8. When installing the packaged CLI, keep the sdk package tar file in the same folder/directory as the CLI (at the same level).
+
+## Releasing the Platform SDK
+
+1. Get your changes in your feature branch merged to the `dev` branch first.
+2. Create a release PR targeting the `alpha` branch from the `dev` branch. Remember to create a proper commit message explaining the changes since the CLI is public-facing.
+3. *⚠️IMPORTANT⚠️* Before you can merge the `dev` branch to the `alpha` branch, you must ask someone from the platform team to disable branch protection on the repo. We are using `semantic-release` package in our github action for releasing & publishing the SDK to NPM, and we have a limitation where `semantic-release` needs to create and push a commit to the `alpha` branch right after release and create a tag for it. If branch protection is disabled, this step gets skipped and the release is incomplete.
+4. Squash-and-merge your changes and verify the release github action succeeds.
+
+## Updating the Latest Version on NPM for Platform SDK after Release
+
+Before you can tag the released version as the `latest` version on NPM, you need an auth token to authenticate with NPM. You will also need to be added to the `apimatic` organisation on NPM. Contact someone from the Platform team if you are unclear about these steps.
+
+1. Switch to the `alpha` branch and pull the latest changes after the release.
+2. Update the `.npmrc` file to add the line `//registry.npmjs.org/:_authToken=<your-npm-auth-token>`. *⚠️DO NOT COMMIT THE AUTH TOKEN TO THE REPOSITORY⚠️*
+3. Run the command `npm dist-tag add @apimatic/sdk@<version-to-tag> latest`. Replace the `<version-to-tag>` placeholder with the actual version to tag as the latest, for e.g. `0.2.0-alpha.7`.
diff --git a/CLAUDE.md b/CLAUDE.md
index e1c17fc7..5227e780 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -15,3 +15,4 @@ Reference these files as needed for scaffolding:
 - `.ai/skills/service.md` — Infrastructure Service conventions and scaffolding
 - `.ai/skills/value-object.md` — Value object (rich class) conventions: encapsulation, boundary unwrapping, composition
 - `.ai/skills/event.md` — Domain event conventions: past-tense naming, variants, where to fire
+- `.ai/skills/contribution-guide.md` — Contribution workflow: branching from `dev`, local debugging/packaging, README updates, releasing the CLI and Platform SDK, NPM tagging
diff --git a/src/infrastructure/service-error.ts b/src/infrastructure/service-error.ts
index 0dca88ae..4a95d84e 100644
--- a/src/infrastructure/service-error.ts
+++ b/src/infrastructure/service-error.ts
@@ -1,4 +1,5 @@
 import axios from "axios";
+import { ApiError } from "@apimatic/sdk";
 import { format as f } from "../prompts/format.js";
 
 export enum ServiceErrorCode {
@@ -30,6 +31,14 @@ export class ServiceError {
   static notFound(customMessage: string): ServiceError {
     return new ServiceError(ServiceErrorCode.NotFound, customMessage, {});
   }
+  static unauthorized(apiMessage: string | null): ServiceError {
+    const message = `${apiMessage ?? "You are not authorized to perform this action."} Please run ${f.cmdAlt(
+      "apimatic",
+      "auth",
+      "login"
+    )} to log in, or provide a valid auth key using the ${f.flag("auth-key")} flag.`;
+    return new ServiceError(ServiceErrorCode.UnAuthorized, message, {});
+  }
 
   static readonly values: ServiceError[] = [
     ServiceError.NotFound,
@@ -55,6 +64,15 @@ export class ServiceError {
 }
 
 export function handleServiceError(error: unknown): ServiceError {
+  // SDK controllers throw typed `ApiError`s (not axios errors). The API reports
+  // the reason as {"message": "..."} deserialized into `result`.
+  if (error instanceof ApiError) {
+    const apiMessage = (error.result as { message?: string } | undefined)?.message ?? null;
+    if (error.statusCode === 401) return ServiceError.unauthorized(apiMessage);
+    if (error.statusCode === 404) return ServiceError.NotFound;
+    if (error.statusCode === 500) return ServiceError.ServerError;
+  }
+
   if (axios.isAxiosError(error)) {
     const status = error.response?.status;
     if (status === 401) return ServiceError.UnAuthorized;
diff --git a/src/infrastructure/services/portal-service.ts b/src/infrastructure/services/portal-service.ts
index e585d77e..75257ffb 100644
--- a/src/infrastructure/services/portal-service.ts
+++ b/src/infrastructure/services/portal-service.ts
@@ -78,6 +78,7 @@ export class PortalService {
           return err(ServiceError.forbidden(errorMessage));
         }
       }
+      // 401 (and other SDK ApiError statuses) are mapped centrally in handleServiceError.
       const serviceError = handleServiceError(error);
       return err(serviceError);
     } finally {