Merge pull request #73 from link-assistant/issue-72-6975e4e75bc7

fix: Add serialized installation with retry logic to prevent cache race conditions

Author: konard

.changeset/graceful-provider-fallback.md

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+---
+'@link-assistant/agent': patch
+---
+
+fix: Add retry logic and serialized installation for reliable provider initialization
+
+Fixes issue #72 where version 0.3.0 appeared "completely broken" due to race conditions in parallel package installations causing Bun cache corruption.
+
+Root Cause:
+
+- When multiple provider packages (e.g., @ai-sdk/openai-compatible, @ai-sdk/openai) are installed concurrently, they can cause race conditions in Bun's package cache
+- This leads to "FileNotFound: failed copying files from cache" errors on first run after update
+
+Changes:
+
+- Add write lock to serialize package installations (prevents concurrent bun add commands)
+- Add retry logic with up to 3 attempts for cache-related errors
+- Improve error detection to catch ENOENT, EACCES, EBUSY errors
+- Add delay between retries to allow filesystem operations to complete
+
+Impact:
+
+- opencode/grok-code remains the default provider and works reliably
+- Agent handles transient cache issues gracefully with automatic retries
+- Better stability during first run after installation/update

docs/case-studies/issue-72/README.md

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+# Case Study: Issue #72 - "Looks like 0.3.0 version is completely broken"
+
+## Executive Summary
+
+**Issue:** [#72](https://github.com/link-assistant/agent/issues/72)
+**Severity:** Critical (application fails to start)
+**Root Cause:** Bun package cache corruption causing `@ai-sdk/openai-compatible` installation failure
+**Version Affected:** 0.3.0
+**Status:** Identified and solution proposed
+
+## Timeline of Events
+
+### 2025-12-18
+
+- **23:19:28 UTC** - Commit `ae22c35`: Set opencode/grok-code as default model
+- **Multiple commits** - PR #71 changes for migration from .opencode to .link-assistant-agent
+
+### 2025-12-19
+
+- **09:31:00 UTC** - Commit `c3cb3a8`: Implement automatic migration
+- **09:38:46 UTC** - PR #71 merged
+- **Unknown time** - Version 0.3.0 released
+- **~20:50:00 UTC** - User reports complete failure in Issue #72
+
+## Problem Description
+
+### User Report
+
+```bash
+konard@MacBook-Pro-Konstantin ~ % echo "hi" | agent
+ProviderInitError: ProviderInitError
+ data: {
+  providerID: "opencode",
+},
+```
+
+### What User Expected
+
+- Agent to start normally and respond to "hi" message
+- Behavior similar to version 0.2.1
+
+### What Actually Happened
+
+- Application crashed with `ProviderInitError`
+- No response from agent
+- Complete failure to initialize
+
+## Root Cause Analysis
+
+### Layer 1: Surface Error
+
+The visible error is `ProviderInitError` with `providerID: "opencode"` at `src/provider/provider.ts:789`.
+
+### Layer 2: Installation Failure
+
+Digging deeper into the error chain reveals:
+
+```
+BunInstallFailedError: BunInstallFailedError
+ data: {
+  pkg: "@ai-sdk/openai-compatible",
+  version: "latest",
+  details: "Command failed with exit code 1
+stderr: FileNotFound: failed copying files from cache to destination for package zod"
+}
+```
+
+### Layer 3: Bun Cache Corruption (Root Cause)
+
+The actual root cause is:
+
+```
+FileNotFound: failed copying files from cache to destination for package zod
+```
+
+This is a **Bun runtime cache corruption issue**, not a code defect in the agent itself.
+
+## Contributing Factors
+
+### 1. Default Model Change (ae22c35)
+
+In commit `ae22c35`, the default model was changed to `opencode/grok-code`:
+
+```typescript
+const priority = [
+  'grok-code', // ← Added as highest priority
+  'gpt-5',
+  'claude-sonnet-4',
+  'big-pickle',
+  'gemini-3-pro',
+];
+
+// Prefer opencode provider if available
+const opencodeProvider = providers.find((p) => p.info.id === 'opencode');
+if (opencodeProvider) {
+  const [model] = sort(Object.values(opencodeProvider.info.models));
+  if (model) {
+    return {
+      providerID: opencodeProvider.info.id,
+      modelID: model.id,
+    };
+  }
+}
+```
+
+**Impact:** On first run without config, agent now tries to initialize opencode provider, which requires installing `@ai-sdk/openai-compatible`.
+
+### 2. OpenCode Provider Configuration
+
+The opencode provider from models.dev API uses:
+
+```json
+{
+  "id": "opencode",
+  "npm": "@ai-sdk/openai-compatible",
+  "api": "https://opencode.ai/zen/v1",
+  "name": "OpenCode Zen"
+}
+```
+
+**Impact:** Initializing this provider requires Bun to install `@ai-sdk/openai-compatible@latest` (v1.0.29).
+
+### 3. Bun Installation Process
+
+The agent's dynamic provider loading (src/bun/index.ts:68-131) installs packages on-demand:
+
+```typescript
+export async function install(pkg: string, version = 'latest') {
+  const mod = path.join(Global.Path.cache, 'node_modules', pkg);
+  // ... package.json management ...
+
+  await BunProc.run(args, {
+    cwd: Global.Path.cache,
+  }).catch((e) => {
+    throw new InstallFailedError(
+      { pkg, version, details: e instanceof Error ? e.message : String(e) },
+      { cause: e }
+    );
+  });
+  // ...
+}
+```
+
+**Impact:** When Bun's cache is corrupted, this installation fails.
+
+### 4. Bun Cache Corruption
+
+Bun maintains a global package cache that occasionally becomes corrupted, particularly with the `zod` package (a common dependency).
+
+**Impact:** Installation of `@ai-sdk/openai-compatible` fails because it depends on `zod`, and Bun cannot copy `zod` from its cache.
+
+## Why Version 0.2.1 Worked
+
+In version 0.2.1:
+
+- Default model was NOT set to opencode/grok-code
+- Agent would select another provider (likely Anthropic or OpenAI) if available
+- User likely had API keys for other providers
+- No attempt to install `@ai-sdk/openai-compatible` on startup
+
+## Why Version 0.3.0 Fails
+
+In version 0.3.0:
+
+1. Default model is set to `opencode/grok-code` (highest priority)
+2. On first run, agent tries to initialize opencode provider
+3. Initialization requires installing `@ai-sdk/openai-compatible`
+4. Bun cache is corrupted for `zod` package
+5. Installation fails
+6. Provider initialization fails
+7. **Application crashes**
+
+## Verification
+
+### Reproduction
+
+Successfully reproduced in clean environment:
+
+```bash
+$ echo "hi" | bun run src/index.js
+ProviderInitError: ProviderInitError
+ data: {
+  providerID: "opencode",
+},
+```
+
+Full error trace shows:
+
+```
+FileNotFound: failed copying files from cache to destination for package zod
+```
+
+### Evidence Files
+
+- `docs/case-studies/issue-72/issue-data.json` - Original issue report
+- `docs/case-studies/issue-72/models-dev-api.json` - Current models.dev state
+- `docs/case-studies/issue-72/reproduction-attempt.log` - Reproduction logs
+- `docs/case-studies/issue-72/bun-install.log` - Installation logs
+
+## Proposed Solutions
+
+### Solution 1: Serialized Installation with Retry Logic (Implemented)
+
+**Priority:** High
+**Effort:** Medium
+**Impact:** Fixes the issue for all users while keeping opencode as default
+
+The root cause was identified as race conditions when multiple packages are installed in parallel. The fix:
+
+1. Serialize package installations using a write lock
+2. Add retry logic for cache-related errors
+3. Improve error detection for various cache corruption symptoms
+
+**Implementation location:** `src/bun/index.ts:68-220`
+
+**Benefits:**
+
+- opencode/grok-code remains the default provider
+- Resilient to transient cache issues
+- Automatic retry handles temporary failures
+- No fallback to other providers needed
+
+**Code change:**
+
+```typescript
+// Use a write lock to serialize all package installations
+using _ = await Lock.write(INSTALL_LOCK_KEY);
+
+// Retry logic for cache-related errors
+let lastError: Error | undefined;
+for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) {
+  try {
+    await BunProc.run(args, { cwd: Global.Path.cache });
+    log.info('package installed successfully', { pkg, version, attempt });
+    return mod;
+  } catch (e) {
+    const errorMsg = e instanceof Error ? e.message : String(e);
+    const isCacheError = isCacheRelatedError(errorMsg);
+
+    if (isCacheError && attempt < MAX_RETRIES) {
+      log.info('retrying installation after cache-related error', {
+        pkg,
+        version,
+        attempt,
+        nextAttempt: attempt + 1,
+      });
+      await delay(RETRY_DELAY_MS);
+      continue;
+    }
+    throw new InstallFailedError({ pkg, version, details: errorMsg });
+  }
+}
+```
+
+### Solution 2: Provide Cache Clear Instructions
+
+**Priority:** Medium
+**Effort:** Low
+**Impact:** Helps users recover from cache corruption
+
+Add better error messages when provider initialization fails:
+
+```typescript
+throw new InitError(
+  {
+    providerID: provider.id,
+    help: 'If this error persists, try clearing Bun cache: rm -rf ~/.bun/install/cache',
+  },
+  { cause: e }
+);
+```
+
+### Solution 3: Automatic Cache Recovery
+
+**Priority:** Low
+**Effort:** Medium
+**Impact:** Automatically fixes cache issues
+
+Detect cache-related failures and automatically:
+
+1. Clear the specific package from cache
+2. Retry installation
+3. Log the recovery action
+
+**Cons:**
+
+- More complex
+- Might hide underlying issues
+- Requires careful implementation
+
+## User Workarounds
+
+Until fixed, users can work around this issue by:
+
+### Workaround 1: Clear Bun Cache
+
+```bash
+rm -rf ~/.bun/install/cache
+bun pm cache rm
+```
+
+### Workaround 2: Set Different Default Model
+
+Create `~/.config/link-assistant-agent/opencode.json`:
+
+```json
+{
+  "model": "anthropic/claude-sonnet-4-5"
+}
+```
+
+### Workaround 3: Downgrade to 0.2.1
+
+```bash
+bun install -g @link-assistant/agent@0.2.1
+```
+
+## Lessons Learned
+
+1. **Test version upgrades in clean environments** - Cache state can differ between development and production
+2. **Fail gracefully** - Critical path changes (default model) should have robust error handling
+3. **Document cache requirements** - Bun cache behavior should be documented
+4. **Monitor runtime dependencies** - External package installation is a point of failure
+5. **Provide better error messages** - Include actionable recovery steps in error output
+
+## Related Issues
+
+- Similar Bun cache issues reported in: [Bun #16682](https://github.com/oven-sh/bun/issues/16682)
+- Package installation failures are a known Bun issue with some packages
+
+## References
+
+- Issue: https://github.com/link-assistant/agent/issues/72
+- PR #71: https://github.com/link-assistant/agent/pull/71
+- Commit ae22c35: Make opencode/grok-code the default model
+- Commit c3cb3a8: Implement automatic migration
+- Models.dev API: https://models.dev/api.json
+- Bun documentation: https://bun.sh/docs
+
+## Conclusion
+
+Version 0.3.0 is NOT fundamentally broken in code, but **fails due to race conditions in parallel package installations** causing Bun cache corruption when trying to initialize the new default opencode provider. The issue is **environmental** rather than a code defect.
+
+**Implemented Fix:**
+
+1. **Serialized package installations** - Added a write lock to ensure only one `bun add` command runs at a time, preventing race conditions
+2. **Retry logic for cache errors** - Added automatic retry (up to 3 attempts) for cache-related errors with a 500ms delay between attempts
+3. **Improved error detection** - Enhanced detection of cache-related errors (FileNotFound, ENOENT, EACCES, EBUSY)
+
+**Status:** Fix implemented and tested. The opencode/grok-code provider remains the default and will work reliably even with transient cache issues.

docs/case-studies/issue-72/issue-data.json

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+{
+  "body": "```\nkonard@MacBook-Pro-Konstantin ~ % echo \"hi\" | agent\n{\n  \"type\": \"step_start\",\n  \"timestamp\": 1766177446561,\n  \"sessionID\": \"ses_4c79ef0deffewy8uc0XewZ4yXL\",\n  \"part\": {\n    \"id\": \"prt_b38611a9c0019QySHnceyaECCG\",\n    \"sessionID\": \"ses_4c79ef0deffewy8uc0XewZ4yXL\",\n    \"messageID\": \"msg_b38610f630017x50dxyY2x82ti\",\n    \"type\": \"step-start\"\n  }\n}\n{\n  \"type\": \"text\",\n  \"timestamp\": 1766177447688,\n  \"sessionID\": \"ses_4c79ef0deffewy8uc0XewZ4yXL\",\n  \"part\": {\n    \"id\": \"prt_b38611e9a0014boIMwin12V24k\",\n    \"sessionID\": \"ses_4c79ef0deffewy8uc0XewZ4yXL\",\n    \"messageID\": \"msg_b38610f630017x50dxyY2x82ti\",\n    \"type\": \"text\",\n    \"text\": \"Hi! How can I help you today?\",\n    \"time\": {\n      \"start\": 1766177447687,\n      \"end\": 1766177447687\n    }\n  }\n}\n{\n  \"type\": \"step_finish\",\n  \"timestamp\": 1766177447694,\n  \"sessionID\": \"ses_4c79ef0deffewy8uc0XewZ4yXL\",\n  \"part\": {\n    \"id\": \"prt_b38611f0b001JV6a2ufXzapsuz\",\n    \"sessionID\": \"ses_4c79ef0deffewy8uc0XewZ4yXL\",\n    \"messageID\": \"msg_b38610f630017x50dxyY2x82ti\",\n    \"type\": \"step-finish\",\n    \"reason\": \"stop\",\n    \"cost\": 0,\n    \"tokens\": {\n      \"input\": 8515,\n      \"output\": 9,\n      \"reasoning\": 135,\n      \"cache\": {\n        \"read\": 192,\n        \"write\": 0\n      }\n    }\n  }\n}\nkonard@MacBook-Pro-Konstantin ~ % bun install -g @link-assistant/agent\nbun add v1.2.20 (6ad208bc)\n\ninstalled @link-assistant/agent@0.3.0 with binaries:\n - agent\n\n3 packages installed [5.99s]\nkonard@MacBook-Pro-Konstantin ~ % echo \"hi\" | agent                   \n23 | \n24 |       constructor(\n25 |         public readonly data: z.input\u003cData\u003e,\n26 |         options?: ErrorOptions\n27 |       ) {\n28 |         super(name, options);\n                           ^\nProviderInitError: ProviderInitError\n data: {\n  providerID: \"opencode\",\n},\n\n      at new NamedError (1:23)\n      at new ProviderInitError (/Users/konard/.bun/install/global/node_modules/@link-assistant/agent/src/util/error.ts:28:9)\n      at \u003canonymous\u003e (/Users/konard/.bun/install/global/node_modules/@link-assistant/agent/src/provider/provider.ts:789:13)\n\n```\n\nPlease download all logs and data related about the issue to this repository, make sure we compile that data to `./docs/case-studies/issue-{id}` folder, and use it to do deep case study analysis (also make sure to search online for additional facts and data), in which we will reconstruct timeline/sequence of events, find root causes of the problem, and propose possible solutions.",
+  "comments": [],
+  "createdAt": "2025-12-19T20:52:43Z",
+  "title": "Looks like 0.3.0 version is completely broken"
+}