claude-sessions-mcp

Instructions

Implementation Reference

• src/lib/session.ts:468-525 (handler)

  Core implementation of getSessionDiffSummary: reads session messages, derives session title from first human message, iterates through messages to find file-history-snapshot events, extracts unique file changes with backup previews, counts snapshots, and returns a structured summary.

  export const getSessionDiffSummary = (projectName: string, sessionId: string) =>
    Effect.gen(function* () {
      const messages = yield* readSession(projectName, sessionId)
  
      // Extract title
      const title = pipe(
        messages,
        A.findFirst((m) => m.type === 'human'),
        O.map((m) => {
          const msg = m.message as { content?: string } | undefined
          const content = msg?.content ?? ''
          return content.slice(0, 50) + (content.length > 50 ? '...' : '')
        }),
        O.getOrElse(() => 'Untitled')
      )
  
      const changes: FileDiffSummary['changes'] = []
      const seenFiles = new Set<string>()
      let snapshotCount = 0
  
      for (const msg of messages) {
        if (msg.type === 'file-history-snapshot') {
          snapshotCount++
          const snapshot = msg as {
            type: string
            snapshot?: {
              trackedFileBackups?: Record<string, { content?: string }>
            }
          }
  
          const backups = snapshot.snapshot?.trackedFileBackups
          if (backups && typeof backups === 'object') {
            for (const [filePath, backup] of Object.entries(backups)) {
              if (!seenFiles.has(filePath)) {
                seenFiles.add(filePath)
                const backupData = backup as { content?: string } | undefined
                const content = backupData?.content ?? ''
                changes.push({
                  path: filePath,
                  action: 'modified',
                  hasBackup: content.length > 0,
                  backupPreview: content.slice(0, 100) + (content.length > 100 ? '...' : ''),
                })
              }
            }
          }
        }
      }
  
      return {
        sessionId,
        projectName,
        title,
        changes,
        totalFiles: changes.length,
        snapshotCount,
      } satisfies FileDiffSummary
    })

• src/mcp/index.ts:154-167 (registration)

  Registers the MCP tool 'get_session_diff' with server.tool, providing description, input schema, and a thin handler that invokes the core getSessionDiffSummary function and returns JSON response.

  server.tool(
    'get_session_diff',
    'Get diff summary for a session including file changes and snapshot info',
    {
      project_name: z.string().describe('Project folder name'),
      session_id: z.string().describe('Session ID'),
    },
    async ({ project_name, session_id }) => {
      const result = await Effect.runPromise(session.getSessionDiffSummary(project_name, session_id))
      return {
        content: [{ type: 'text', text: JSON.stringify(result, null, 2) }],
      }
    }
  )

• src/mcp/index.ts:157-160 (schema)

  Zod input schema defining required string parameters: project_name and session_id for the get_session_diff tool.

  {
    project_name: z.string().describe('Project folder name'),
    session_id: z.string().describe('Session ID'),
  },