diff --git a/docs/porting-from-pi-mono.md b/docs/porting-from-pi-mono.md
index 567f3440c..baceca91f 100644
--- a/docs/porting-from-pi-mono.md
+++ b/docs/porting-from-pi-mono.md
@@ -82,7 +82,7 @@ We run on Bun. Replace Node APIs only when Bun provides a better alternative.
 
 ```typescript
 // BROKEN: env vars may be undefined, "~" is not expanded
-const home = Bun.env.HOME || Bun.env.HOME || "~";
+const home = Bun.env.HOME || "~";
 const tmp = Bun.env.TMPDIR || "/tmp";
 ```
 
diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index f5a75706c..9d23ec9c1 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -1,8 +1,13 @@
 # Changelog
 
 ## [Unreleased]
+
 ### Added
 
+- Added documentation for additional LLM provider API keys (Groq, Cerebras, xAI, OpenRouter, Mistral, z.ai, MiniMax, OpenCode, Cursor, Vercel AI Gateway) in environment variables reference
+- Added documentation for cloud provider configuration (AWS Bedrock, Google Vertex AI) in environment variables reference
+- Added documentation for search provider API keys (Perplexity, Anthropic Search) in environment variables reference
+- Added documentation for model override environment variables (`PI_SMOL_MODEL`, `PI_SLOW_MODEL`, `PI_PLAN_MODEL`) in CLI help text
 - Added comprehensive environment variables reference documentation at `docs/environment-variables.md` covering API keys, configuration, debugging, and testing variables
 - Added theme system with 44 customizable color tokens, two built-in themes (dark/light), and auto-detection based on terminal background
 - Added `/theme` command to interactively select and switch between themes
diff --git a/packages/coding-agent/docs/environment-variables.md b/packages/coding-agent/docs/environment-variables.md
index 4bea134ed..b2df20623 100644
--- a/packages/coding-agent/docs/environment-variables.md
+++ b/packages/coding-agent/docs/environment-variables.md
@@ -16,6 +16,17 @@ This document lists all environment variables used by the coding agent.
 | `GH_TOKEN` | GitHub CLI token (fallback for Copilot) | - |
 | `GITHUB_TOKEN` | GitHub token (fallback for Copilot and API access) | - |
 | `EXA_API_KEY` | Exa search API key | - |
+| `GROQ_API_KEY` | Groq API key for Llama and other models | - |
+| `CEREBRAS_API_KEY` | Cerebras API key | - |
+| `XAI_API_KEY` | xAI API key for Grok models | - |
+| `OPENROUTER_API_KEY` | OpenRouter aggregated models API key | - |
+| `MISTRAL_API_KEY` | Mistral AI API key | - |
+| `ZAI_API_KEY` | z.ai API key (ZhipuAI/GLM models) | - |
+| `MINIMAX_API_KEY` | MiniMax API key | - |
+| `OPENCODE_API_KEY` | OpenCode API key | - |
+| `CURSOR_ACCESS_TOKEN` | Cursor AI access token | - |
+| `AI_GATEWAY_API_KEY` | Vercel AI Gateway API key | - |
+| `PERPLEXITY_API_KEY` | Perplexity search API key | - |
 
 ### Provider-Specific Configuration
 
diff --git a/packages/coding-agent/src/cli/args.ts b/packages/coding-agent/src/cli/args.ts
index 550648cd2..1e36310f6 100644
--- a/packages/coding-agent/src/cli/args.ts
+++ b/packages/coding-agent/src/cli/args.ts
@@ -287,7 +287,45 @@ ${chalk.bold("Environment Variables:")}
 
   ${chalk.dim("# Configuration")}
   PI_CODING_AGENT_DIR    - Session storage directory (default: ~/${CONFIG_DIR_NAME}/agent)
+${chalk.bold("API Keys (Environment Variables):")}
+  ${chalk.dim("# Core Providers")}
+  ANTHROPIC_API_KEY          - Anthropic Claude models
+  ANTHROPIC_OAUTH_TOKEN      - Anthropic OAuth (takes precedence over API key)
+  OPENAI_API_KEY             - OpenAI GPT models
+  GOOGLE_API_KEY             - Google Gemini models
+  GITHUB_TOKEN               - GitHub Copilot (or GH_TOKEN, COPILOT_GITHUB_TOKEN)
 
+  ${chalk.dim("# Additional LLM Providers")}
+  AZURE_OPENAI_API_KEY       - Azure OpenAI models
+  GROQ_API_KEY               - Groq models
+  CEREBRAS_API_KEY           - Cerebras models
+  XAI_API_KEY                - xAI Grok models
+  OPENROUTER_API_KEY         - OpenRouter aggregated models
+  MISTRAL_API_KEY            - Mistral models
+  ZAI_API_KEY                - z.ai models (ZhipuAI/GLM)
+  MINIMAX_API_KEY            - MiniMax models
+  OPENCODE_API_KEY           - OpenCode models
+  CURSOR_ACCESS_TOKEN        - Cursor AI models
+  AI_GATEWAY_API_KEY         - Vercel AI Gateway
+
+  ${chalk.dim("# Cloud Providers")}
+  AWS_PROFILE                - AWS Bedrock (or AWS_ACCESS_KEY_ID + AWS_SECRET_ACCESS_KEY)
+  GOOGLE_CLOUD_PROJECT       - Google Vertex AI (requires GOOGLE_CLOUD_LOCATION)
+  GOOGLE_APPLICATION_CREDENTIALS - Service account for Vertex AI
+
+  ${chalk.dim("# Search & Tools")}
+  EXA_API_KEY                - Exa web search
+  PERPLEXITY_API_KEY         - Perplexity web search
+  ANTHROPIC_SEARCH_API_KEY   - Anthropic search provider
+
+  ${chalk.dim("# Configuration")}
+  PI_CODING_AGENT_DIR        - Session storage directory (default: ~/${CONFIG_DIR_NAME}/agent)
+  PI_SMOL_MODEL              - Override smol/fast model (see --smol)
+  PI_SLOW_MODEL              - Override slow/reasoning model (see --slow)
+  PI_PLAN_MODEL              - Override planning model (see --plan)
+
+  For complete environment variable reference, see:
+  ${chalk.dim("docs/environment-variables.md")}
 ${chalk.bold("Available Tools (all enabled by default):")}
   read       - Read file contents
   bash       - Execute bash commands