feat: refactor SSE queue, expand test coverage, fix package metadata

- Extract createSseQueue() helper, eliminating duplicated SSE queue pattern
  in /v1/chat/completions and /v1/responses streaming branches (closes #34)
- Add tests for GET /v1/models happy path, empty providers, and error path (closes #33)
- Add tests for POST /v1/responses: happy path, validation, streaming, session.error (closes #32)
- Fix package.json description to be provider-agnostic (closes #35)
- Add engines field declaring bun >=1.0.0 requirement (closes #35)
- Line coverage: 55% -> 89%, function coverage: 83% -> 94%

Author: KochC

index.js

@@ -487,6 +487,48 @@ export async function resolveModel(client, requestedModel, providerOverride) {
   throw new Error(`Unknown model '${requestedModel}'. Call GET /v1/models to inspect available IDs.`)
 }
 
+export function createSseQueue() {
+  const chunks = []
+  let resolve = null
+  let done = false
+
+  function enqueue(value) {
+    chunks.push(value)
+    if (resolve) {
+      const r = resolve
+      resolve = null
+      r()
+    }
+  }
+
+  function finish() {
+    done = true
+    if (resolve) {
+      const r = resolve
+      resolve = null
+      r()
+    }
+  }
+
+  async function* generateChunks() {
+    while (true) {
+      while (chunks.length > 0) {
+        yield chunks.shift()
+      }
+      if (done) break
+      await new Promise((r) => {
+        resolve = r
+      })
+    }
+    // Drain any remaining chunks
+    while (chunks.length > 0) {
+      yield chunks.shift()
+    }
+  }
+
+  return { enqueue, finish, generateChunks }
+}
+
 function sseResponse(corsHeadersObj, generator) {
   const encoder = new TextEncoder()
   const body = new ReadableStream({
@@ -595,18 +637,7 @@ export function createProxyFetchHandler(client) {
         const completionID = `chatcmpl_${crypto.randomUUID().replace(/-/g, "")}`
         const now = Math.floor(Date.now() / 1000)
 
-        const chunks = []
-        let resolve = null
-        let done = false
-
-        function enqueue(value) {
-          chunks.push(value)
-          if (resolve) {
-            const r = resolve
-            resolve = null
-            r()
-          }
-        }
+        const queue = createSseQueue()
 
         async function* generateSse() {
           const runPromise = executePromptStreaming(
@@ -622,7 +653,7 @@ export function createProxyFetchHandler(client) {
                 model: model.id,
                 choices: [{ index: 0, delta: { role: "assistant", content: delta }, finish_reason: null }],
               })
-              enqueue(`data: ${chunk}\n\n`)
+              queue.enqueue(`data: ${chunk}\n\n`)
             },
           )
             .then((streamResult) => {
@@ -638,7 +669,7 @@ export function createProxyFetchHandler(client) {
                   total_tokens: streamResult.tokens.input + streamResult.tokens.output,
                 },
               })
-              enqueue(`data: ${finalChunk}\n\ndata: [DONE]\n\n`)
+              queue.enqueue(`data: ${finalChunk}\n\ndata: [DONE]\n\n`)
             })
             .catch(async (err) => {
               const streamError = err instanceof Error ? err.message : String(err)
@@ -649,30 +680,13 @@ export function createProxyFetchHandler(client) {
               const errChunk = JSON.stringify({
                 error: { message: streamError, type: "server_error" },
               })
-              enqueue(`data: ${errChunk}\n\ndata: [DONE]\n\n`)
+              queue.enqueue(`data: ${errChunk}\n\ndata: [DONE]\n\n`)
             })
             .finally(() => {
-              done = true
-              if (resolve) {
-                const r = resolve
-                resolve = null
-                r()
-              }
+              queue.finish()
             })
 
-          while (true) {
-            while (chunks.length > 0) {
-              yield chunks.shift()
-            }
-            if (done) break
-            await new Promise((r) => {
-              resolve = r
-            })
-          }
-          // Drain any remaining chunks
-          while (chunks.length > 0) {
-            yield chunks.shift()
-          }
+          yield* queue.generateChunks()
 
           await runPromise
         }
@@ -739,25 +753,14 @@ export function createProxyFetchHandler(client) {
         const itemID = `msg_${crypto.randomUUID().replace(/-/g, "")}`
         const now = Math.floor(Date.now() / 1000)
 
-        const chunks = []
-        let resolve = null
-        let done = false
-
-        function enqueue(value) {
-          chunks.push(value)
-          if (resolve) {
-            const r = resolve
-            resolve = null
-            r()
-          }
-        }
+        const queue = createSseQueue()
 
         function sseEvent(eventType, data) {
           return `event: ${eventType}\ndata: ${JSON.stringify(data)}\n\n`
         }
 
         async function* generateSse() {
-          enqueue(
+          queue.enqueue(
             sseEvent("response.created", {
               type: "response.created",
               response: {
@@ -770,7 +773,7 @@ export function createProxyFetchHandler(client) {
               },
             }),
           )
-          enqueue(
+          queue.enqueue(
             sseEvent("response.output_item.added", {
               type: "response.output_item.added",
               output_index: 0,
@@ -786,7 +789,7 @@ export function createProxyFetchHandler(client) {
             system,
             (delta) => {
               if (partIndex === 0) {
-                enqueue(
+                queue.enqueue(
                   sseEvent("response.content_part.added", {
                     type: "response.content_part.added",
                     item_id: itemID,
@@ -797,7 +800,7 @@ export function createProxyFetchHandler(client) {
                 )
                 partIndex++
               }
-              enqueue(
+              queue.enqueue(
                 sseEvent("response.output_text.delta", {
                   type: "response.output_text.delta",
                   item_id: itemID,
@@ -809,7 +812,7 @@ export function createProxyFetchHandler(client) {
             },
           )
             .then((streamResult) => {
-              enqueue(
+              queue.enqueue(
                 sseEvent("response.output_text.done", {
                   type: "response.output_text.done",
                   item_id: itemID,
@@ -818,14 +821,14 @@ export function createProxyFetchHandler(client) {
                   text: "",
                 }),
               )
-              enqueue(
+              queue.enqueue(
                 sseEvent("response.output_item.done", {
                   type: "response.output_item.done",
                   output_index: 0,
                   item: { id: itemID, type: "message", status: "completed", role: "assistant" },
                 }),
               )
-              enqueue(
+              queue.enqueue(
                 sseEvent("response.completed", {
                   type: "response.completed",
                   response: {
@@ -849,7 +852,7 @@ export function createProxyFetchHandler(client) {
                 error: errMsg,
                 requestedModel: body.model,
               })
-              enqueue(
+              queue.enqueue(
                 sseEvent("response.failed", {
                   type: "response.failed",
                   response: {
@@ -863,26 +866,10 @@ export function createProxyFetchHandler(client) {
               )
             })
             .finally(() => {
-              done = true
-              if (resolve) {
-                const r = resolve
-                resolve = null
-                r()
-              }
+              queue.finish()
             })
 
-          while (true) {
-            while (chunks.length > 0) {
-              yield chunks.shift()
-            }
-            if (done) break
-            await new Promise((r) => {
-              resolve = r
-            })
-          }
-          while (chunks.length > 0) {
-            yield chunks.shift()
-          }
+          yield* queue.generateChunks()
 
           await runPromise
         }