diff --git a/src/renderer/pages/code/cliConfig/__tests__/dotenv.test.ts b/src/renderer/pages/code/cliConfig/__tests__/dotenv.test.ts
index 797be16521..2c94baf84f 100644
--- a/src/renderer/pages/code/cliConfig/__tests__/dotenv.test.ts
+++ b/src/renderer/pages/code/cliConfig/__tests__/dotenv.test.ts
@@ -1,3 +1,4 @@
+import { parse as parseWithRealDotenv } from 'dotenv'
 import { describe, expect, it } from 'vitest'
 
 import { parseDotenv, renderDotenvFile } from '../dotenv'
@@ -7,22 +8,51 @@ describe('renderDotenvFile', () => {
     expect(renderDotenvFile(new Map([['KEY', 'value']]))).toBe('KEY=value\n')
   })
 
-  it('quotes a value containing #', () => {
+  it('single-quotes a value containing # (single quotes are read back 100% literally)', () => {
     expect(renderDotenvFile(new Map([['HTTPS_PROXY', 'http://user:p#ss@host']]))).toBe(
-      'HTTPS_PROXY="http://user:p#ss@host"\n'
+      "HTTPS_PROXY='http://user:p#ss@host'\n"
     )
   })
 
-  it('quotes a value with leading/trailing whitespace', () => {
-    expect(renderDotenvFile(new Map([['KEY', ' value ']]))).toBe('KEY=" value "\n')
+  it('single-quotes a value with leading/trailing whitespace', () => {
+    expect(renderDotenvFile(new Map([['KEY', ' value ']]))).toBe("KEY=' value '\n")
   })
 
-  it('quotes and escapes a value containing a double quote', () => {
-    expect(renderDotenvFile(new Map([['KEY', 'say "hi"']]))).toBe('KEY="say \\"hi\\""\n')
+  it('single-quotes a value containing a double quote instead of escaping it', () => {
+    // The real `dotenv` package only re-expands `\n`/`\r` in double-quoted values on read — it never
+    // unescapes `\"`, so a `\"`-escaped double-quoted value would come back with the backslash intact.
+    expect(renderDotenvFile(new Map([['KEY', 'say "hi"']]))).toBe(`KEY='say "hi"'\n`)
   })
 
-  it('quotes an empty value', () => {
-    expect(renderDotenvFile(new Map([['KEY', '']]))).toBe('KEY=""\n')
+  it('single-quotes an empty value', () => {
+    expect(renderDotenvFile(new Map([['KEY', '']]))).toBe("KEY=''\n")
+  })
+
+  it('falls back to double-quoting (unescaped) a value containing a single quote', () => {
+    expect(renderDotenvFile(new Map([['KEY', "it's fine"]]))).toBe(`KEY="it's fine"\n`)
+  })
+
+  it('does not double a backslash in a Windows-style path value', () => {
+    // Regression: escaping `\` to `\\` here corrupted the value on read-back, since the real
+    // `dotenv` package never unescapes `\\` — it would come back with twice as many backslashes.
+    expect(renderDotenvFile(new Map([['KEY', 'C:\\Users\\me']]))).toBe("KEY='C:\\Users\\me'\n")
+  })
+})
+
+describe('renderDotenvFile output round-trips through the real dotenv package', () => {
+  const cases = [
+    'plain-value',
+    'http://user:p#ss@host',
+    ' leading-and-trailing ',
+    'say "hi"',
+    '',
+    'C:\\Users\\me',
+    'sk-proj-\\backslash\\and-hash#mixed'
+  ]
+
+  it.each(cases)('renders %j so the real dotenv package reads it back unchanged', (value) => {
+    const rendered = renderDotenvFile(new Map([['KEY', value]]))
+    expect(parseWithRealDotenv(rendered).KEY).toBe(value)
   })
 })
 
diff --git a/src/renderer/pages/code/cliConfig/__tests__/draftFiles.test.ts b/src/renderer/pages/code/cliConfig/__tests__/draftFiles.test.ts
index 0cc8499dee..d75e5cf3f2 100644
--- a/src/renderer/pages/code/cliConfig/__tests__/draftFiles.test.ts
+++ b/src/renderer/pages/code/cliConfig/__tests__/draftFiles.test.ts
@@ -1,7 +1,8 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
-import { readAndParseDraftFile } from '../draftFiles'
+import { readAndParseDraftFile, validateCliConfigDraftForWrite } from '../draftFiles'
 import { parseTomlOrThrow } from '../file'
+import type { CliConfigFileDraft } from '../types'
 
 describe('readAndParseDraftFile (secret redaction on parse failure)', () => {
   beforeEach(() => {
@@ -23,3 +24,19 @@ describe('readAndParseDraftFile (secret redaction on parse failure)', () => {
     await expect(readAndParseDraftFile('kimi-config', parseTomlOrThrow)).rejects.not.toThrow(/sk-ant-real-secret/)
   })
 })
+
+describe('validateCliConfigDraftForWrite (secret redaction when editing config text directly)', () => {
+  it('does not leak the raw secret from a malformed in-editor TOML draft into the thrown error', () => {
+    const files: CliConfigFileDraft[] = [
+      {
+        target: 'kimi-config',
+        label: 'Kimi config',
+        path: '/resolved~/.kimi-code/config.toml',
+        language: 'toml',
+        content: 'api_key = "sk-ant-real-secret"\nbroken====='
+      }
+    ]
+    expect(() => validateCliConfigDraftForWrite(files)).toThrow(/api_key = "<redacted>"/)
+    expect(() => validateCliConfigDraftForWrite(files)).not.toThrow(/sk-ant-real-secret/)
+  })
+})
diff --git a/src/renderer/pages/code/cliConfig/__tests__/redact.test.ts b/src/renderer/pages/code/cliConfig/__tests__/redact.test.ts
index 810b8c0ccd..ff32bb4845 100644
--- a/src/renderer/pages/code/cliConfig/__tests__/redact.test.ts
+++ b/src/renderer/pages/code/cliConfig/__tests__/redact.test.ts
@@ -1,7 +1,19 @@
+import { parse as parseToml } from 'smol-toml'
 import { describe, expect, it } from 'vitest'
 
 import { redactSecretsInMessage } from '../redact'
 
+/** Parse malformed TOML and return smol-toml's own thrown message (which embeds a raw source
+ * codeblock), so redaction is tested against a real error shape rather than a hand-crafted string. */
+function realTomlParseErrorMessage(malformedToml: string): string {
+  try {
+    parseToml(malformedToml)
+    throw new Error('expected malformed TOML to throw')
+  } catch (err) {
+    return err instanceof Error ? err.message : String(err)
+  }
+}
+
 describe('redactSecretsInMessage', () => {
   it('redacts a quoted TOML-style api_key assignment', () => {
     expect(redactSecretsInMessage('unexpected character at line 3: api_key = "sk-ant-real-secret"')).toBe(
@@ -42,4 +54,22 @@ describe('redactSecretsInMessage', () => {
     const result = redactSecretsInMessage(message)
     expect(result).not.toContain('sk-ant-real-secret')
   })
+
+  it('redacts a secret stranded after a broken/empty quoted value on a real smol-toml error', () => {
+    // A missing separator splits the value into an empty quoted pair followed by the real secret as
+    // a bare trailing token — smol-toml's own message embeds the raw source line verbatim.
+    const message = realTomlParseErrorMessage('api_key = "" sk-ant-REALSECRET')
+    expect(message).toContain('sk-ant-REALSECRET') // sanity: the real message does leak it pre-redaction
+    expect(redactSecretsInMessage(message)).not.toContain('sk-ant-REALSECRET')
+  })
+
+  it('redacts a double-quoted secret containing an apostrophe on a real smol-toml error', () => {
+    // smol-toml's codeblock includes the line before the actual error line too, so a perfectly valid
+    // secret line can still end up embedded in the message when a later line is what fails to parse.
+    // A naive ["'][^"']*["'] value match stops at the embedded apostrophe, leaking the tail (the part
+    // of the secret after it) even though the quoted value read as a whole is fully redacted.
+    const message = realTomlParseErrorMessage(`api_key = "sk-ant-don't-SECRET"\nbroken=====`)
+    expect(message).toContain('SECRET') // sanity: the real message does leak it pre-redaction
+    expect(redactSecretsInMessage(message)).not.toContain('SECRET')
+  })
 })
diff --git a/src/renderer/pages/code/cliConfig/__tests__/writeCliConfigDraft.test.ts b/src/renderer/pages/code/cliConfig/__tests__/writeCliConfigDraft.test.ts
index 63253962a2..d39da2c9ee 100644
--- a/src/renderer/pages/code/cliConfig/__tests__/writeCliConfigDraft.test.ts
+++ b/src/renderer/pages/code/cliConfig/__tests__/writeCliConfigDraft.test.ts
@@ -962,6 +962,43 @@ describe('writeCliConfigDraft', () => {
       ).rejects.toThrow(/missing the API key/)
       expect(writes).toEqual([])
     })
+
+    it('rejects opencode with an API key but no resolvable endpoint base URL, and writes nothing', async () => {
+      const noEndpointProvider = { id: 'noendpoint', name: 'NoEndpoint', endpointConfigs: {} } as unknown as Provider
+      mockGet({
+        '/providers/noendpoint': () => noEndpointProvider,
+        '/providers/noendpoint/api-keys': () => ({ keys: [enabledKey] }),
+        '/models/': () => ({ id: 'some-model', contextWindow: 65536 })
+      })
+      await expect(
+        writeCliConfigDraft({ cliTool: CodeCli.OPEN_CODE, modelId: 'noendpoint::some-model' })
+      ).rejects.toThrow(/missing required fields/)
+      expect(writes).toEqual([])
+    })
+
+    it('rejects qwen-code with an API key but no OpenAI-compatible endpoint base URL, and writes nothing', async () => {
+      mockGet({
+        '/providers/anthropic': () => anthropicProvider,
+        '/providers/anthropic/api-keys': () => ({ keys: [enabledKey] }),
+        '/models/': () => ({ id: 'claude-sonnet-4-5', name: 'Claude Sonnet 4.5' })
+      })
+      await expect(
+        writeCliConfigDraft({ cliTool: CodeCli.QWEN_CODE, modelId: 'anthropic::claude-sonnet-4-5' })
+      ).rejects.toThrow(/missing the OpenAI endpoint base URL/)
+      expect(writes).toEqual([])
+    })
+
+    it('rejects kimi-code with an API key but no OpenAI-compatible endpoint base URL, and writes nothing', async () => {
+      mockGet({
+        '/providers/anthropic': () => anthropicProvider,
+        '/providers/anthropic/api-keys': () => ({ keys: [enabledKey] }),
+        '/models/': () => ({ id: 'claude-sonnet-4-5', contextWindow: 200000 })
+      })
+      await expect(
+        writeCliConfigDraft({ cliTool: CodeCli.KIMI_CODE, modelId: 'anthropic::claude-sonnet-4-5' })
+      ).rejects.toThrow(/missing the OpenAI endpoint base URL/)
+      expect(writes).toEqual([])
+    })
   })
 
   describe('read-error safety (a real read failure must not be treated as "file missing")', () => {
diff --git a/src/renderer/pages/code/cliConfig/dotenv.ts b/src/renderer/pages/code/cliConfig/dotenv.ts
index 1343415b93..8cee52035a 100644
--- a/src/renderer/pages/code/cliConfig/dotenv.ts
+++ b/src/renderer/pages/code/cliConfig/dotenv.ts
@@ -25,8 +25,14 @@ function needsDotenvQuoting(value: string): boolean {
   return value === '' || /^\s|\s$|["'#\\]/.test(value)
 }
 
+// The real `dotenv` package (used by the CLI tools that read these files back) only re-expands
+// literal `\n`/`\r` sequences inside a double-quoted value on read — it does NOT unescape `\\` or
+// `\"`, so injecting those escapes here would corrupt the value on read-back instead of preserving
+// it. A single-quoted value, by contrast, is taken back 100% literally with no escape processing at
+// all, so prefer it whenever the value has no embedded single quote to conflict with the wrapper.
 function quoteDotenvValue(value: string): string {
-  return `"${value.replace(/\\/g, '\\\\').replace(/"/g, '\\"')}"`
+  if (!value.includes("'")) return `'${value}'`
+  return `"${value.replace(/\r/g, '\\r').replace(/\n/g, '\\n')}"`
 }
 
 export function renderDotenvFile(envMap: Map<string, string>): string {
diff --git a/src/renderer/pages/code/cliConfig/draftFiles.ts b/src/renderer/pages/code/cliConfig/draftFiles.ts
index 2653031c6c..be156f343e 100644
--- a/src/renderer/pages/code/cliConfig/draftFiles.ts
+++ b/src/renderer/pages/code/cliConfig/draftFiles.ts
@@ -1,6 +1,5 @@
 import { parseDotenv } from './dotenv'
 import { parseJsonOrThrow, parseTomlOrThrow, readExternal, resolveAbs } from './file'
-import { redactSecretsInMessage } from './redact'
 import { CLI_CONFIG_FILE_SPECS } from './targets'
 import type { CliConfigFileDraft, CliConfigTarget } from './types'
 
@@ -39,10 +38,11 @@ export async function readAndParseDraftFile<T>(
   try {
     return parseFn(content)
   } catch (err) {
+    // parseFn (parseJsonOrThrow/parseTomlOrThrow) already redacts its own message at the source.
     const spec = CLI_CONFIG_FILE_SPECS[target]
     const path = getDraftFile(files, target)?.path ?? (await resolveAbs(spec.path))
     const rawMessage = err instanceof Error ? err.message : String(err)
-    throw new Error(`Failed to parse ${spec.label} at ${path}: ${redactSecretsInMessage(rawMessage)}`)
+    throw new Error(`Failed to parse ${spec.label} at ${path}: ${rawMessage}`)
   }
 }
 
diff --git a/src/renderer/pages/code/cliConfig/file.ts b/src/renderer/pages/code/cliConfig/file.ts
index 7e2fcab8b1..28842d02da 100644
--- a/src/renderer/pages/code/cliConfig/file.ts
+++ b/src/renderer/pages/code/cliConfig/file.ts
@@ -50,8 +50,10 @@ function parseOrThrow<T>(content: string, label: string, absPath: string, parseF
   try {
     return parseFn(content)
   } catch (err) {
+    // parseFn (parseJsonOrThrow/parseTomlOrThrow) already redacts its own message at the source, so
+    // every caller — this wrapper, validateCliConfigDraftForWrite, draftUpdater.ts — is covered.
     const rawMessage = err instanceof Error ? err.message : String(err)
-    throw new Error(`Failed to parse ${label} at ${absPath}: ${redactSecretsInMessage(rawMessage)}`)
+    throw new Error(`Failed to parse ${label} at ${absPath}: ${rawMessage}`)
   }
 }
 
@@ -79,7 +81,14 @@ export async function readValidatedTomlOrNull(absPath: string, label: string): P
 
 export function parseTomlOrThrow(content: string): Record<string, any> {
   if (!content) return {}
-  return parseToml(content) as Record<string, any>
+  try {
+    return parseToml(content) as Record<string, any>
+  } catch (err) {
+    // smol-toml embeds a source codeblock (the offending line +/- 1) straight into its own message,
+    // so this must be redacted right here — every call site (direct or through parseOrThrow) inherits it.
+    const rawMessage = err instanceof Error ? err.message : String(err)
+    throw new Error(redactSecretsInMessage(rawMessage))
+  }
 }
 
 export function parseJsonOrThrow(content: string): Record<string, any> {
diff --git a/src/renderer/pages/code/cliConfig/redact.ts b/src/renderer/pages/code/cliConfig/redact.ts
index 90058c372c..ff9aa817e2 100644
--- a/src/renderer/pages/code/cliConfig/redact.ts
+++ b/src/renderer/pages/code/cliConfig/redact.ts
@@ -1,10 +1,13 @@
 const BEARER_TOKEN_PATTERN = /\bBearer\s+\S+/gi
 
-// Triple-quoted alternatives must come before the single-quote-pair alternative — otherwise that
-// alternative matches only up to the first quote inside the triple-quoted block, leaving the rest
-// of a multiline TOML secret unredacted.
+// Triple-quoted alternatives must come before the bare-value fallback — otherwise a multiline TOML
+// secret is only redacted up to the first embedded newline. The bare-value fallback intentionally
+// consumes the rest of the line (not just one token): a malformed source line can put the real
+// secret past a broken/empty quoted value (e.g. `api_key = "" sk-real-secret`), or inside a
+// double-quoted value containing an apostrophe (e.g. `api_key = "sk-real's-secret"`) — matching only
+// a single quoted pair or token would leave those trailing fragments unredacted.
 const SENSITIVE_MESSAGE_PATTERN =
-  /(["']?(?:api[_-]?key|token|secret|password|auth)\w*["']?\s*[:=]\s*)("""[\s\S]*?"""|'''[\s\S]*?'''|["'][^"']*["']|\S+)/gi
+  /(["']?(?:api[_-]?key|token|secret|password|auth)\w*["']?\s*[:=]\s*)("""[\s\S]*?"""|'''[\s\S]*?'''|[^\r\n]*)/gi
 
 /** Redact likely-sensitive key=value / "key": value / Bearer-token fragments embedded in a raw parser error message. */
 export function redactSecretsInMessage(message: string): string {