fix: VMware Tanzu Platform provider - bug fixes, streaming, UI improvements (#8126)

Signed-off-by: Nick Kuhn <nick.kuhn@broadcom.com>
Signed-off-by: Douwe Osinga <douwe@squareup.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Douwe Osinga <douwe@squareup.com>

documentation/docs/guides/tanzu-cli-testing-guide.md

@@ -0,0 +1,149 @@
+# VMware Tanzu Platform - CLI Testing Guide
+
+## Prerequisites
+
+- goose CLI built from the `feat/tanzu-ai-provider` branch
+- A Tanzu AI Services endpoint and API key (single-model or multi-model plan)
+
+## Locate the CLI Binary
+
+**macOS:**
+```bash
+# If built from source:
+export GOOSE_CLI=~/claude/goose-fork/target/release/goose
+
+# Verify:
+$GOOSE_CLI --version
+```
+
+**Linux:**
+```bash
+# If installed via .deb:
+export GOOSE_CLI=/usr/bin/goose
+
+# If built from source:
+export GOOSE_CLI=~/goose-fork/target/release/goose
+
+# Verify:
+$GOOSE_CLI --version
+```
+
+## Test 1: Configure VMware Tanzu Platform Provider
+
+```bash
+goose configure
+```
+
+1. Select **Configure Providers**
+2. Scroll to / search for **VMware Tanzu Platform**
+3. When prompted for **TANZU_AI_ENDPOINT**, enter your endpoint URL:
+   - Single-model: `https://genai-proxy.sys.example.com/tanzu-my-model-abc1234`
+   - Multi-model: `https://genai-proxy.sys.example.com/tanzu-all-models-abc1234`
+4. When prompted for **TANZU_AI_API_KEY**, paste the JWT token from your service key
+5. Select a model from the dynamically fetched list
+
+**Expected:** Models are fetched from the endpoint and displayed for selection.
+
+## Test 2: Start a Session (Single-Model Plan)
+
+```bash
+export TANZU_AI_ENDPOINT="https://genai-proxy.sys.tas-tdc.kuhn-labs.com/tanzu-Qwen3-Coder-30B-A3B-vllm-v1-f3b0d18"
+export TANZU_AI_API_KEY="<your-jwt-token>"
+
+goose session
+```
+
+Type a simple prompt:
+```
+> What is 2 + 2?
+```
+
+**Expected:** The model responds with an answer. If streaming is enabled, tokens appear incrementally.
+
+## Test 3: Start a Session (Multi-Model Plan)
+
+```bash
+export TANZU_AI_ENDPOINT="https://genai-proxy.sys.tas-tdc.kuhn-labs.com/tanzu-all-models-a8a9e22"
+export TANZU_AI_API_KEY="<your-jwt-token>"
+
+goose session
+```
+
+**Expected:** Session starts with whichever model was selected during `goose configure`.
+
+## Test 4: Verify Streaming
+
+With streaming enabled (`supports_streaming: true`), responses should appear token-by-token rather than all at once.
+
+```
+> Write a short poem about clouds
+```
+
+**Expected:** Text streams in progressively, not appearing all at once after a delay.
+
+## Test 5: Verify Dynamic Model Fetching
+
+```bash
+goose configure
+```
+
+Select **Configure Providers** > **VMware Tanzu Platform**.
+
+**Expected for single-model plan:** One model appears (e.g., `Qwen/Qwen3-Coder-30B-A3B-Instruct-FP8`)
+**Expected for multi-model plan:** Multiple models appear (e.g., `Qwen3.5-122B`, `Qwen3-Coder-30B`, `gpt-oss-120b`)
+
+## Test 6: Verify Error Messages
+
+### Missing API Key
+```bash
+unset TANZU_AI_API_KEY
+goose session
+```
+**Expected:** Clear error message: "Required API key TANZU_AI_API_KEY is not set."
+
+### Missing Endpoint
+```bash
+unset TANZU_AI_ENDPOINT
+goose session
+```
+**Expected:** Clear error message about TANZU_AI_ENDPOINT not being set.
+
+### Wrong Endpoint
+```bash
+export TANZU_AI_ENDPOINT="https://genai-proxy.sys.example.com/nonexistent"
+export TANZU_AI_API_KEY="invalid-key"
+goose session
+```
+**Expected:** Connection or authentication error, not a crash.
+
+## Test 7: Switch Between Plans
+
+1. Configure with multi-model endpoint, select a model, start a session, verify it works
+2. Run `goose configure` again
+3. Change TANZU_AI_ENDPOINT to the single-model endpoint
+4. Select the single model
+5. Start a new session, verify it works
+
+**Expected:** Both plans work without needing to restart goose.
+
+## Quick Curl Verification
+
+Before testing with goose, you can verify endpoints directly:
+
+```bash
+# Test models endpoint
+curl -s -H "Authorization: Bearer $TANZU_AI_API_KEY" \
+  "$TANZU_AI_ENDPOINT/openai/v1/models" | python3 -m json.tool
+
+# Test chat completions
+curl -s -X POST "$TANZU_AI_ENDPOINT/openai/v1/chat/completions" \
+  -H "Authorization: Bearer $TANZU_AI_API_KEY" \
+  -H "Content-Type: application/json" \
+  -d '{"model":"Qwen/Qwen3-Coder-30B-A3B-Instruct-FP8","messages":[{"role":"user","content":"hello"}],"max_tokens":10}'
+
+# Test streaming
+curl -s -N -X POST "$TANZU_AI_ENDPOINT/openai/v1/chat/completions" \
+  -H "Authorization: Bearer $TANZU_AI_API_KEY" \
+  -H "Content-Type: application/json" \
+  -d '{"model":"Qwen/Qwen3-Coder-30B-A3B-Instruct-FP8","messages":[{"role":"user","content":"hello"}],"max_tokens":10,"stream":true}'
+```