diff --git a/packages/console/app/src/routes/zen/util/provider/anthropic.ts b/packages/console/app/src/routes/zen/util/provider/anthropic.ts
index a5f92a29acf..04bfb94fa92 100644
--- a/packages/console/app/src/routes/zen/util/provider/anthropic.ts
+++ b/packages/console/app/src/routes/zen/util/provider/anthropic.ts
@@ -191,8 +191,8 @@ export function fromAnthropicRequest(body: any): CommonRequest {
       if (!s) continue
       if ((s as any).type !== "text") continue
       if (typeof (s as any).text !== "string") continue
-      if ((s as any).text.length === 0) continue
-      msgs.push({ role: "system", content: (s as any).text })
+      if ((s as any).text.trim().length === 0) continue
+      msgs.push({ role: "system", content: (s as any).text.trim() })
     }
   }
 
@@ -221,8 +221,10 @@ export function fromAnthropicRequest(body: any): CommonRequest {
       const partsOut: any[] = []
       for (const p of partsIn) {
         if (!p || !(p as any).type) continue
-        if ((p as any).type === "text" && typeof (p as any).text === "string")
-          partsOut.push({ type: "text", text: (p as any).text })
+        if ((p as any).type === "text" && typeof (p as any).text === "string") {
+          const t = (p as any).text.trim()
+          if (t.length > 0) partsOut.push({ type: "text", text: t })
+        }
         if ((p as any).type === "image") {
           const ip = toImg((p as any).source)
           if (ip) partsOut.push(ip)
@@ -247,7 +249,10 @@ export function fromAnthropicRequest(body: any): CommonRequest {
       const tcs: any[] = []
       for (const p of partsIn) {
         if (!p || !(p as any).type) continue
-        if ((p as any).type === "text" && typeof (p as any).text === "string") texts.push((p as any).text)
+        if ((p as any).type === "text" && typeof (p as any).text === "string") {
+          const t = (p as any).text.trim()
+          if (t.length > 0) texts.push(t)
+        }
         if ((p as any).type === "tool_use") {
           const name = (p as any).name
           const id = (p as any).id
@@ -324,8 +329,8 @@ export function toAnthropicRequest(body: CommonRequest) {
     return ccCount <= 4 ? { cache_control: { type: "ephemeral" } } : {}
   }
   const system = sysIn
-    .filter((m: any) => typeof m.content === "string" && m.content.length > 0)
-    .map((m: any) => ({ type: "text", text: m.content, ...cc() }))
+    .filter((m: any) => typeof m.content === "string" && m.content.trim().length > 0)
+    .map((m: any) => ({ type: "text", text: m.content.trim(), ...cc() }))
 
   const msgsIn = Array.isArray(body.messages) ? body.messages : []
   const msgsOut: any[] = []
@@ -348,16 +353,21 @@ export function toAnthropicRequest(body: CommonRequest) {
 
     if ((m as any).role === "user") {
       if (typeof (m as any).content === "string") {
-        msgsOut.push({
-          role: "user",
-          content: [{ type: "text", text: (m as any).content, ...cc() }],
-        })
+        const c = (m as any).content.trim()
+        if (c.length > 0) {
+          msgsOut.push({
+            role: "user",
+            content: [{ type: "text", text: c, ...cc() }],
+          })
+        }
       } else if (Array.isArray((m as any).content)) {
         const parts: any[] = []
         for (const p of (m as any).content) {
           if (!p || !(p as any).type) continue
-          if ((p as any).type === "text" && typeof (p as any).text === "string")
-            parts.push({ type: "text", text: (p as any).text, ...cc() })
+          if ((p as any).type === "text" && typeof (p as any).text === "string") {
+            const t = (p as any).text.trim()
+            if (t.length > 0) parts.push({ type: "text", text: t, ...cc() })
+          }
           if ((p as any).type === "image_url") {
             const s = toSrc(p)
             if (s) parts.push({ type: "image", source: s, ...cc() })
@@ -370,8 +380,8 @@ export function toAnthropicRequest(body: CommonRequest) {
 
     if ((m as any).role === "assistant") {
       const out: any = { role: "assistant", content: [] as any[] }
-      if (typeof (m as any).content === "string" && (m as any).content.length > 0) {
-        ;(out.content as any[]).push({ type: "text", text: (m as any).content, ...cc() })
+      if (typeof (m as any).content === "string" && (m as any).content.trim().length > 0) {
+        ;(out.content as any[]).push({ type: "text", text: (m as any).content.trim(), ...cc() })
       }
       if (Array.isArray((m as any).tool_calls)) {
         for (const tc of (m as any).tool_calls) {
@@ -554,8 +564,8 @@ export function toAnthropicResponse(resp: CommonResponse) {
 
   const content: any[] = []
 
-  if (typeof message.content === "string" && message.content.length > 0)
-    content.push({ type: "text", text: message.content })
+  if (typeof message.content === "string" && message.content.trim().length > 0)
+    content.push({ type: "text", text: message.content.trim() })
 
   if (Array.isArray(message.tool_calls)) {
     for (const tc of message.tool_calls) {
diff --git a/packages/console/app/src/routes/zen/util/provider/openai-compatible.ts b/packages/console/app/src/routes/zen/util/provider/openai-compatible.ts
index 699243d085f..2a94d53e286 100644
--- a/packages/console/app/src/routes/zen/util/provider/openai-compatible.ts
+++ b/packages/console/app/src/routes/zen/util/provider/openai-compatible.ts
@@ -81,18 +81,22 @@ export function fromOaCompatibleRequest(body: any): CommonRequest {
     if (!m || !m.role) continue
 
     if (m.role === "system") {
-      if (typeof m.content === "string" && m.content.length > 0) msgsOut.push({ role: "system", content: m.content })
+      if (typeof m.content === "string" && m.content.trim().length > 0)
+        msgsOut.push({ role: "system", content: m.content.trim() })
       continue
     }
 
     if (m.role === "user") {
-      if (typeof m.content === "string") {
-        msgsOut.push({ role: "user", content: m.content })
+      if (typeof m.content === "string" && m.content.trim().length > 0) {
+        msgsOut.push({ role: "user", content: m.content.trim() })
       } else if (Array.isArray(m.content)) {
         const parts: any[] = []
         for (const p of m.content) {
           if (!p || !p.type) continue
-          if (p.type === "text" && typeof p.text === "string") parts.push({ type: "text", text: p.text })
+          if (p.type === "text" && typeof p.text === "string") {
+            const t = p.text.trim()
+            if (t.length > 0) parts.push({ type: "text", text: t })
+          }
           if (p.type === "image_url") parts.push({ type: "image_url", image_url: p.image_url })
         }
         if (parts.length === 1 && parts[0].type === "text") msgsOut.push({ role: "user", content: parts[0].text })
@@ -103,7 +107,7 @@ export function fromOaCompatibleRequest(body: any): CommonRequest {
 
     if (m.role === "assistant") {
       const out: any = { role: "assistant" }
-      if (typeof m.content === "string") out.content = m.content
+      if (typeof m.content === "string" && m.content.trim().length > 0) out.content = m.content.trim()
       if (Array.isArray(m.tool_calls)) out.tool_calls = m.tool_calls
       msgsOut.push(out)
       continue
@@ -149,20 +153,24 @@ export function toOaCompatibleRequest(body: CommonRequest) {
     if (!m || !m.role) continue
 
     if (m.role === "system") {
-      if (typeof m.content === "string" && m.content.length > 0) msgsOut.push({ role: "system", content: m.content })
+      if (typeof m.content === "string" && m.content.trim().length > 0)
+        msgsOut.push({ role: "system", content: m.content.trim() })
       continue
     }
 
     if (m.role === "user") {
-      if (typeof m.content === "string") {
-        msgsOut.push({ role: "user", content: m.content })
+      if (typeof m.content === "string" && m.content.trim().length > 0) {
+        msgsOut.push({ role: "user", content: m.content.trim() })
         continue
       }
       if (Array.isArray(m.content)) {
         const parts: any[] = []
         for (const p of m.content) {
           if (!p || !p.type) continue
-          if (p.type === "text" && typeof p.text === "string") parts.push({ type: "text", text: p.text })
+          if (p.type === "text" && typeof p.text === "string") {
+            const t = p.text.trim()
+            if (t.length > 0) parts.push({ type: "text", text: t })
+          }
           const ip = toImg(p)
           if (ip) parts.push(ip)
         }
@@ -174,7 +182,7 @@ export function toOaCompatibleRequest(body: CommonRequest) {
 
     if (m.role === "assistant") {
       const out: any = { role: "assistant" }
-      if (typeof m.content === "string") out.content = m.content
+      if (typeof m.content === "string" && m.content.trim().length > 0) out.content = m.content.trim()
       if (Array.isArray(m.tool_calls)) out.tool_calls = m.tool_calls
       msgsOut.push(out)
       continue
@@ -224,8 +232,8 @@ export function fromOaCompatibleResponse(resp: any): CommonResponse {
 
   const content: any[] = []
 
-  if (typeof message.content === "string" && message.content.length > 0) {
-    content.push({ type: "text", text: message.content })
+  if (typeof message.content === "string" && message.content.trim().length > 0) {
+    content.push({ type: "text", text: message.content.trim() })
   }
 
   if (Array.isArray(message.tool_calls)) {
diff --git a/packages/console/app/src/routes/zen/util/provider/openai.ts b/packages/console/app/src/routes/zen/util/provider/openai.ts
index f4d7699e97c..9b29b729a3d 100644
--- a/packages/console/app/src/routes/zen/util/provider/openai.ts
+++ b/packages/console/app/src/routes/zen/util/provider/openai.ts
@@ -115,24 +115,25 @@ export function fromOpenaiRequest(body: any): CommonRequest {
 
     if ((m as any).role === "system" || (m as any).role === "developer") {
       const c = (m as any).content
-      if (typeof c === "string" && c.length > 0) msgs.push({ role: "system", content: c })
+      if (typeof c === "string" && c.trim().length > 0) msgs.push({ role: "system", content: c.trim() })
       if (Array.isArray(c)) {
         const t = c.find((p: any) => p && typeof p.text === "string")
-        if (t && typeof t.text === "string" && t.text.length > 0) msgs.push({ role: "system", content: t.text })
+        if (t && typeof t.text === "string" && t.text.trim().length > 0)
+          msgs.push({ role: "system", content: t.text.trim() })
       }
       continue
     }
 
     if ((m as any).role === "user") {
       const c = (m as any).content
-      if (typeof c === "string") {
-        msgs.push({ role: "user", content: c })
-      } else if (Array.isArray(c)) {
+      if (typeof c === "string" && c.trim().length > 0) msgs.push({ role: "user", content: c.trim() })
+      else if (Array.isArray(c)) {
         const parts: any[] = []
         for (const p of c) {
           if (!p || !(p as any).type) continue
-          if (((p as any).type === "text" || (p as any).type === "input_text") && typeof (p as any).text === "string")
-            parts.push({ type: "text", text: (p as any).text })
+          if (((p as any).type === "text" || (p as any).type === "input_text") && typeof (p as any).text === "string") {
+            if ((p as any).text.trim().length > 0) parts.push({ type: "text", text: (p as any).text.trim() })
+          }
           const ip = toImg(p)
           if (ip) parts.push(ip)
           if ((p as any).type === "tool_result") {
@@ -151,7 +152,7 @@ export function fromOpenaiRequest(body: any): CommonRequest {
     if ((m as any).role === "assistant") {
       const c = (m as any).content
       const out: any = { role: "assistant" }
-      if (typeof c === "string" && c.length > 0) out.content = c
+      if (typeof c === "string" && c.trim().length > 0) out.content = c.trim()
       if (Array.isArray((m as any).tool_calls)) out.tool_calls = (m as any).tool_calls
       msgs.push(out)
       continue
@@ -206,8 +207,11 @@ export function toOpenaiRequest(body: CommonRequest) {
 
   const toPart = (p: any) => {
     if (!p || typeof p !== "object") return undefined
-    if ((p as any).type === "text" && typeof (p as any).text === "string")
-      return { type: "input_text", text: (p as any).text }
+    if ((p as any).type === "text" && typeof (p as any).text === "string") {
+      const t = (p as any).text.trim()
+      if (t.length === 0) return undefined
+      return { type: "input_text", text: t }
+    }
     if ((p as any).type === "image_url" && (p as any).image_url)
       return { type: "input_image", image_url: (p as any).image_url }
     const s = (p as any).source
@@ -231,15 +235,17 @@ export function toOpenaiRequest(body: CommonRequest) {
 
     if ((m as any).role === "system") {
       const c = (m as any).content
-      if (typeof c === "string") input.push({ role: "system", content: c })
+      if (typeof c === "string" && c.trim().length > 0) input.push({ role: "system", content: c.trim() })
       continue
     }
 
     if ((m as any).role === "user") {
       const c = (m as any).content
-      if (typeof c === "string") {
-        input.push({ role: "user", content: [{ type: "input_text", text: c }] })
-      } else if (Array.isArray(c)) {
+      if (typeof c === "string" && c.trim().length > 0) {
+        input.push({ role: "user", content: [{ type: "input_text", text: c.trim() }] })
+        continue
+      }
+      if (Array.isArray(c)) {
         const parts: any[] = []
         for (const p of c) {
           const op = toPart(p)
@@ -252,8 +258,8 @@ export function toOpenaiRequest(body: CommonRequest) {
 
     if ((m as any).role === "assistant") {
       const c = (m as any).content
-      if (typeof c === "string" && c.length > 0) {
-        input.push({ role: "assistant", content: [{ type: "output_text", text: c }] })
+      if (typeof c === "string" && c.trim().length > 0) {
+        input.push({ role: "assistant", content: [{ type: "output_text", text: c.trim() }] })
       }
       if (Array.isArray((m as any).tool_calls)) {
         for (const tc of (m as any).tool_calls) {
@@ -417,13 +423,13 @@ export function toOpenaiResponse(resp: CommonResponse) {
 
   const outputItems: any[] = []
 
-  if (typeof msg.content === "string" && msg.content.length > 0) {
+  if (typeof msg.content === "string" && msg.content.trim().length > 0) {
     outputItems.push({
       id: `msg_${Math.random().toString(36).slice(2)}`,
       type: "message",
       status: "completed",
       role: "assistant",
-      content: [{ type: "output_text", text: msg.content, annotations: [], logprobs: [] }],
+      content: [{ type: "output_text", text: msg.content.trim(), annotations: [], logprobs: [] }],
     })
   }
 
diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index f6b7ec8cbcc..53ed69651ee 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -49,20 +49,33 @@ export namespace ProviderTransform {
       msgs = msgs
         .map((msg) => {
           if (typeof msg.content === "string") {
-            if (msg.content === "") return undefined
-            return msg
+            if (msg.content.trim().length === 0) return undefined
+            return { ...msg, content: msg.content.trim() }
           }
           if (!Array.isArray(msg.content)) return msg
-          const filtered = msg.content.filter((part) => {
-            if (part.type === "text" || part.type === "reasoning") {
-              return part.text !== ""
-            }
-            return true
-          })
+          const filtered = msg.content
+            .filter((part) => {
+              if (part.type === "text" || part.type === "reasoning") {
+                if (typeof (part as any).text === "string") return (part as any).text.trim().length > 0
+                return false
+              }
+              return true
+            })
+            .map((part) => {
+              if ((part.type === "text" || part.type === "reasoning") && typeof (part as any).text === "string") {
+                return { ...part, text: (part as any).text.trim() }
+              }
+              return part
+            })
           if (filtered.length === 0) return undefined
           return { ...msg, content: filtered }
         })
-        .filter((msg): msg is ModelMessage => msg !== undefined && msg.content !== "")
+        .filter((msg): msg is ModelMessage => {
+          if (msg === undefined) return false
+          if (typeof msg.content === "string") return msg.content.length > 0
+          if (Array.isArray(msg.content)) return msg.content.length > 0
+          return true
+        })
     }
 
     if (model.api.id.includes("claude")) {
diff --git a/packages/opencode/test/provider/transform.test.ts b/packages/opencode/test/provider/transform.test.ts
index 2b8f1872f56..e0c68ee01bc 100644
--- a/packages/opencode/test/provider/transform.test.ts
+++ b/packages/opencode/test/provider/transform.test.ts
@@ -596,6 +596,97 @@ describe("ProviderTransform.message - anthropic empty content filtering", () =>
     expect(result[0].content[1]).toEqual({ type: "text", text: "Result" })
   })
 
+  test("filters out messages with whitespace-only string content", () => {
+    const msgs = [
+      { role: "user", content: "Hello" },
+      { role: "assistant", content: "   " },
+      { role: "assistant", content: "\t\n  " },
+      { role: "user", content: "World" },
+    ] as any[]
+
+    const result = ProviderTransform.message(msgs, anthropicModel, {})
+
+    expect(result).toHaveLength(2)
+    expect(result[0].content).toBe("Hello")
+    expect(result[1].content).toBe("World")
+  })
+
+  test("filters out whitespace-only text parts from array content", () => {
+    const msgs = [
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "  " },
+          { type: "text", text: "Hello" },
+          { type: "text", text: "\t\n" },
+          { type: "reasoning", text: "   " },
+          { type: "text", text: "World" },
+        ],
+      },
+    ] as any[]
+
+    const result = ProviderTransform.message(msgs, anthropicModel, {})
+
+    expect(result).toHaveLength(1)
+    expect(result[0].content).toHaveLength(2)
+    expect(result[0].content[0]).toEqual({ type: "text", text: "Hello" })
+    expect(result[0].content[1]).toEqual({ type: "text", text: "World" })
+  })
+
+  test("removes entire message when all parts are whitespace-only", () => {
+    const msgs = [
+      { role: "user", content: "Hello" },
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "  " },
+          { type: "reasoning", text: "\t" },
+        ],
+      },
+      { role: "user", content: "World" },
+    ] as any[]
+
+    const result = ProviderTransform.message(msgs, anthropicModel, {})
+
+    expect(result).toHaveLength(2)
+    expect(result[0].content).toBe("Hello")
+    expect(result[1].content).toBe("World")
+  })
+
+  test("trims leading and trailing whitespace from string content", () => {
+    const msgs = [
+      { role: "user", content: "  Hello  " },
+      { role: "assistant", content: "  World\t\n" },
+    ] as any[]
+
+    const result = ProviderTransform.message(msgs, anthropicModel, {})
+
+    expect(result).toHaveLength(2)
+    expect(result[0].content).toBe("Hello")
+    expect(result[1].content).toBe("World")
+  })
+
+  test("trims leading and trailing whitespace from array text content", () => {
+    const msgs = [
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "  Hello  " },
+          { type: "text", text: "\nWorld\t" },
+          { type: "reasoning", text: "  Thinking  " },
+        ],
+      },
+    ] as any[]
+
+    const result = ProviderTransform.message(msgs, anthropicModel, {})
+
+    expect(result).toHaveLength(1)
+    expect(result[0].content).toHaveLength(3)
+    expect(result[0].content[0]).toEqual({ type: "text", text: "Hello" })
+    expect(result[0].content[1]).toEqual({ type: "text", text: "World" })
+    expect(result[0].content[2]).toEqual({ type: "reasoning", text: "Thinking" })
+  })
+
   test("does not filter for non-anthropic providers", () => {
     const openaiModel = {
       ...anthropicModel,