diff --git a/README.md b/README.md
index 6eaf2e3..70daaca 100644
--- a/README.md
+++ b/README.md
@@ -127,6 +127,13 @@ Slack alert via `FACTORY_CANARY_SLACK_WEBHOOK` on failure. See
 `scripts/com.agentrelay.factory-canary.plist.example` for an every-6h launchd
 template.
 
+### Slack questions
+
+Set `slack.channel` to the Slack channel name, channel ID, or mounted channel
+directory. For example, `factory`, `C1234567890`, and
+`C1234567890__factory` are all accepted when the channel is present under the
+relayfile Slack mount.
+
 ## Tell it what to work on
 
 Two ways to hand the factory an issue — both are just labeling/titling, nothing
diff --git a/src/orchestrator/factory.test.ts b/src/orchestrator/factory.test.ts
index 7577389..907c66b 100644
--- a/src/orchestrator/factory.test.ts
+++ b/src/orchestrator/factory.test.ts
@@ -6875,6 +6875,39 @@ describe('FactoryLoop', () => {
     expect(mount.confirmedPaths.filter((path) => path.includes('/replies/'))).toEqual([])
   })
 
+  it('resolves a configured Slack channel name to the mounted channel directory', async () => {
+    const channelDir = 'C0FACTORY__factory-e2e'
+    const mount = new ConfirmRecordingSlackMountClient({
+      [issuePath(35)]: issueFile(35),
+      [`/slack/channels/${channelDir}/meta.json`]: {},
+    })
+    const fleet = new FakeFleetClient()
+    const factory = createFactory(config({ slack: slackConfig('factory-e2e') }), {
+      mount,
+      fleet,
+      triage: new StaticTriage(),
+    })
+
+    await factory.dispatch(await factory.triageIssue(parseLinearIssue(issuePath(35), issueFile(35))))
+
+    const slackRoots = mount.writes.filter((write) => isSlackRootWritePath(write.path))
+    expect(slackRoots).toHaveLength(1)
+    expect(slackRoots[0]?.path).toMatch(new RegExp(`^/slack/channels/${channelDir}/messages/`))
+    expect(fleet.messages[0]?.text).toContain(`/slack/channels/${channelDir}/messages/${mount.threadTs.replace(/\./g, '_')}/replies/question.json`)
+
+    emitSlackReply(mount, slackReplyFixturePath(channelDir, mount.threadTs, 'human-answer-35'), 'human-answer-35', {
+      text: 'Use the mounted channel directory.',
+      user: 'U123',
+      user_is_bot: false,
+    })
+    await flush()
+    await flush()
+
+    expect(slackAnswerInputs(fleet)).toEqual([
+      { name: 'ar-35-impl-pear', data: '<integration-event source="slack" issue="AR-35">\nHuman reply in the Slack thread:\nUse the mounted channel directory.\n</integration-event>\r' },
+    ])
+  })
+
   it('routes a mid-task agent question to the Slack dispatch thread and returns the human answer via sendInput', async () => {
     const mount = new ConfirmRecordingSlackMountClient({ [issuePath(36)]: issueFile(36) })
     const fleet = new FakeFleetClient()
diff --git a/src/orchestrator/factory.ts b/src/orchestrator/factory.ts
index 78f6192..5442df0 100644
--- a/src/orchestrator/factory.ts
+++ b/src/orchestrator/factory.ts
@@ -53,7 +53,7 @@ import type {
   TriageDecision,
   TriageEngine,
 } from '../types'
-import { MountGithubRead, MountLinearWriteback, MountSlackWriteback } from '../writeback'
+import { MountGithubRead, MountLinearWriteback, MountSlackWriteback, slackChannelAliases, slackChannelSegment } from '../writeback'
 import { asRecord, parseJsonContent, stableHash, wrappedPayload } from '../writeback/shared'
 import { type InFlightIssue, issueKey, type TrackedAgent } from './batch-tracker'
 import { findAgentProcessByName, readProcessIdentity, type AgentProcessFinder } from './process-identity'
@@ -194,6 +194,8 @@ export class FactoryLoop implements Factory {
   readonly #resumeInFlight = new Map<string, Promise<void>>()
   readonly #slackWatchers = new Map<string, SlackThreadWatcher>()
   readonly #slackWatcherStarts = new Map<string, Promise<void>>()
+  #resolvedSlackChannelDir?: string
+  #slackChannelDirRefresh?: Promise<string | undefined>
   // Agents we've already logged an ambiguous-PID-lookup warning for, so the
   // reaper doesn't spam the same benign "ambiguous process lookup" line on every
   // poll (a joined/cloud agent has no local PID to resolve — expected).
@@ -2833,12 +2835,15 @@ export class FactoryLoop implements Factory {
 
       if (this.#slack && this.#config.slack && !await this.#shouldSkipSlackWriteback('merge-done-thread')) {
         try {
-          const root = await this.#slack.postThread({
-            channel: this.#config.slack.channel,
-            text: `${issue.key}: PR merged; Linear state set to Done.`,
-          })
-          await this.#slack.reply(root.threadId, `${issue.key}: Linear state set to Done.`)
-          this.#recordSlackWritebackSuccess('merge-done-thread')
+          const channel = await this.#slackChannelDir()
+          if (channel) {
+            const root = await this.#slack.postThread({
+              channel,
+              text: `${issue.key}: PR merged; Linear state set to Done.`,
+            })
+            await this.#slack.reply(root.threadId, `${issue.key}: Linear state set to Done.`)
+            this.#recordSlackWritebackSuccess('merge-done-thread')
+          }
         } catch (error) {
           this.#markSlackWritebackFailure('merge-done-thread', error)
         }
@@ -3084,21 +3089,24 @@ export class FactoryLoop implements Factory {
 
       if (this.#slack && this.#config.slack && !await this.#shouldSkipSlackWriteback('completion-thread')) {
         try {
-          const merged = opts.completionReason === 'pr-merged'
-          const completionText = merged
-            ? `${record.issue.key}: PR merged; Linear state set to ${statusLabel}.`
-            : `${record.issue.key}: factory agents completed${humanReview ? '; awaiting human review' : ''}.\nStatus: ${statusLabel}\nMerge policy: ${this.#config.mergePolicy}`
-          const stateText = merged
-            ? `${record.issue.key}: PR merged; Linear state set to ${statusLabel}.`
-            : humanReview
-              ? `${record.issue.key}: awaiting human review; Linear state set to ${statusLabel}.`
-              : `${record.issue.key}: Linear state set to ${statusLabel}.`
-          const root = await this.#slack.postThread({
-            channel: this.#config.slack.channel,
-            text: completionText,
-          })
-          await this.#slack.reply(root.threadId, stateText)
-          this.#recordSlackWritebackSuccess('completion-thread')
+          const channel = await this.#slackChannelDir()
+          if (channel) {
+            const merged = opts.completionReason === 'pr-merged'
+            const completionText = merged
+              ? `${record.issue.key}: PR merged; Linear state set to ${statusLabel}.`
+              : `${record.issue.key}: factory agents completed${humanReview ? '; awaiting human review' : ''}.\nStatus: ${statusLabel}\nMerge policy: ${this.#config.mergePolicy}`
+            const stateText = merged
+              ? `${record.issue.key}: PR merged; Linear state set to ${statusLabel}.`
+              : humanReview
+                ? `${record.issue.key}: awaiting human review; Linear state set to ${statusLabel}.`
+                : `${record.issue.key}: Linear state set to ${statusLabel}.`
+            const root = await this.#slack.postThread({
+              channel,
+              text: completionText,
+            })
+            await this.#slack.reply(root.threadId, stateText)
+            this.#recordSlackWritebackSuccess('completion-thread')
+          }
         } catch (error) {
           this.#markSlackWritebackFailure('completion-thread', error)
         }
@@ -3362,7 +3370,7 @@ export class FactoryLoop implements Factory {
     }
 
     const root = await this.#slack.postThread({
-      channel: this.#config.slack.channel,
+      channel: await this.#slackChannelDir() ?? this.#config.slack.channel,
       text: [
         `${record.issue.key}: factory agents dispatched.`,
         `State: ${result.stateId ?? 'dispatching'}`,
@@ -3427,7 +3435,7 @@ export class FactoryLoop implements Factory {
 
     const issue = await this.#readIssue(decision.issue.path)
     const root = await this.#slack.postThread({
-      channel: this.#config.slack.channel,
+      channel: await this.#slackChannelDir() ?? this.#config.slack.channel,
       text: [
         `${decision.issue.key}: factory triage escalation for ${issue?.title ?? decision.issue.key}`,
         `Reason: ${reason}`,
@@ -3449,7 +3457,7 @@ export class FactoryLoop implements Factory {
       return
     }
 
-    const channelDir = this.#config.slack.channel
+    const channelDir = await this.#slackChannelDir() ?? this.#config.slack.channel
     const messagesPrefix = slackChannelMessagesPrefix(channelDir)
     const preExistingPaths = new Set<string>()
     const seenReplies = new Set<string>()
@@ -3687,14 +3695,86 @@ export class FactoryLoop implements Factory {
     return resolve(process.cwd(), '.integrations')
   }
 
+  async #slackChannelDir(): Promise<string | undefined> {
+    if (!this.#config.slack) {
+      return undefined
+    }
+    if (this.#resolvedSlackChannelDir) {
+      return this.#resolvedSlackChannelDir
+    }
+    if (this.#slackChannelDirRefresh) {
+      return this.#slackChannelDirRefresh
+    }
+
+    this.#slackChannelDirRefresh = this.#resolveSlackChannelDir()
+      .finally(() => {
+        this.#slackChannelDirRefresh = undefined
+      })
+    return this.#slackChannelDirRefresh
+  }
+
+  async #resolveSlackChannelDir(): Promise<string | undefined> {
+    const configured = this.#config.slack?.channel.trim()
+    if (!configured) {
+      return undefined
+    }
+
+    const configuredSegment = slackChannelSegment(configured)
+    const configuredAliases = slackChannelAliases(configured)
+    if (configuredAliases.size === 0) {
+      return undefined
+    }
+
+    let paths: string[]
+    try {
+      paths = await this.#mount.listTree('/slack/channels')
+    } catch (error) {
+      this.#logger.warn?.('[factory] unable to resolve Slack channel from mount; using configured channel value', {
+        channel: configured,
+        error,
+      })
+      this.#resolvedSlackChannelDir = configuredSegment
+      return this.#resolvedSlackChannelDir
+    }
+
+    const channelDirs = [...new Set(paths
+      .map((path) => path.match(/^\/slack\/channels\/([^/]+)/u)?.[1])
+      .filter((channelDir): channelDir is string => Boolean(channelDir)))]
+      .sort()
+    const matches = channelDirs.filter((channelDir) => {
+      const aliases = slackChannelAliases(channelDir)
+      return [...aliases].some((alias) => configuredAliases.has(alias))
+    })
+
+    if (matches.length === 0) {
+      this.#logger.warn?.('[factory] Slack channel was not found in mount; using configured channel value', {
+        channel: configured,
+      })
+      this.#resolvedSlackChannelDir = configuredSegment
+      return this.#resolvedSlackChannelDir
+    }
+
+    const exact = matches.find((channelDir) => slackChannelSegment(channelDir).toLowerCase() === configuredSegment.toLowerCase())
+    this.#resolvedSlackChannelDir = exact ?? matches[0]
+    if (matches.length > 1 && !exact) {
+      this.#logger.warn?.('[factory] Slack channel name matched multiple mount directories; using first match', {
+        channel: configured,
+        selected: this.#resolvedSlackChannelDir,
+        matches,
+      })
+    }
+    return this.#resolvedSlackChannelDir
+  }
+
   async #slackDispatchThreadFor(record: InFlightIssue): Promise<{ channel: string; threadId: string; mountRoot: string } | undefined> {
     if (!this.#config.slack) {
       return undefined
     }
 
     const threadId = await this.#state.getSlackThread(this.#workspaceId, issueKey(record.issue))
+    const channel = await this.#slackChannelDir() ?? this.#config.slack.channel
     return threadId
-      ? { channel: this.#config.slack.channel, threadId, mountRoot: this.#integrationsMountRoot() }
+      ? { channel, threadId, mountRoot: this.#integrationsMountRoot() }
       : undefined
   }
 
diff --git a/src/writeback/index.ts b/src/writeback/index.ts
index 2c3091a..83d80f6 100644
--- a/src/writeback/index.ts
+++ b/src/writeback/index.ts
@@ -10,6 +10,8 @@ export type {
 } from './linear'
 export {
   MountSlackWriteback,
+  slackChannelAliases,
+  slackChannelSegment,
 } from './slack'
 export type {
   MountSlackWritebackConfig,
diff --git a/src/writeback/slack.ts b/src/writeback/slack.ts
index 3e79e6f..e452068 100644
--- a/src/writeback/slack.ts
+++ b/src/writeback/slack.ts
@@ -16,14 +16,14 @@ interface ThreadRef {
 
 const channelIdFromDir = (channelDir: string): string => channelDir.split('__')[0] ?? channelDir
 
-const channelSegment = (value: string): string => {
+export const slackChannelSegment = (value: string): string => {
   const trimmed = value.trim().replace(/^#/u, '')
   const match = trimmed.match(/(?:^|\/)slack\/channels\/([^/]+)/u)
   return match?.[1] ?? trimmed.split('/')[0] ?? trimmed
 }
 
-const channelAliases = (value?: string): Set<string> => {
-  const segment = typeof value === 'string' ? channelSegment(value) : ''
+export const slackChannelAliases = (value?: string): Set<string> => {
+  const segment = typeof value === 'string' ? slackChannelSegment(value) : ''
   if (!segment) return new Set()
 
   const aliases = new Set<string>()
@@ -45,8 +45,8 @@ const assertSlackChannelAllowed = (
   targetChannel: string | undefined,
   context: string,
 ): void => {
-  const configured = channelAliases(configuredChannel)
-  const target = channelAliases(targetChannel)
+  const configured = slackChannelAliases(configuredChannel)
+  const target = slackChannelAliases(targetChannel)
   if (configured.size === 0) {
     throw new Error(`Refusing Slack writeback for ${context}: configured factory-e2e channel is required`)
   }