diff --git a/src/mcp/cli.ts b/src/mcp/cli.ts
index 3daf77d..e8e2e4d 100644
--- a/src/mcp/cli.ts
+++ b/src/mcp/cli.ts
@@ -22,6 +22,11 @@ import {
     allClients,
     type McpServerEntry,
 } from './install'
+import {
+    parseFlags,
+    buildEntryFromFlags,
+    type ParsedFlags,
+} from './install/flags'
 
 const HELP = `agentmark-mcp — Model Context Protocol server for AgentMark
 
@@ -47,7 +52,22 @@ OPTIONS (install / setup / uninstall)
                     Known: ${allClients().map((c) => c.id).join(', ')}
   --name=<name>     Entry name to register under (default: agentmark)
   --command=<path>  Absolute command path to register (default: auto-detected)
+  --env=KEY=VALUE   Add an env var that the client launches the MCP server
+                    with. Repeatable. Used to wire THINKFLEET_* credentials
+                    so the memory plugin talks to your ThinkFleet workspace
+                    instead of the on-disk default backend.
+
+                    Security note: the value is written into the client's
+                    MCP config file on disk. Prefer rotating secrets from
+                    an OS keychain (ThinkFleet Desktop does this) rather
+                    than passing long-lived keys on a shared machine.
   --dry-run         Show what would change without writing
+
+EXAMPLE — wire Claude Code to ThinkFleet memory:
+  agentmark-mcp install --client=claude-code \\
+      --env=THINKFLEET_BASE_URL=https://app.thinkfleet.ai \\
+      --env=THINKFLEET_PROJECT_ID=proj_xxx \\
+      --env=THINKFLEET_API_KEY=sk-xxx
 `
 
 async function main(argv: string[]): Promise<number> {
@@ -80,7 +100,7 @@ async function main(argv: string[]): Promise<number> {
 
 async function runInstall(args: string[]): Promise<number> {
     const flags = parseFlags(args)
-    const entry = buildEntryFromFlags(flags)
+    const entry = entryForCli(flags)
     const result = await installToClients({
         clientIds: flags.client,
         entry,
@@ -115,39 +135,8 @@ async function runDoctor(): Promise<number> {
     return 0
 }
 
-interface ParsedFlags {
-    client: string[] | undefined
-    name: string[] | undefined
-    command: string[] | undefined
-    dryRun: boolean
-}
-
-function parseFlags(args: string[]): ParsedFlags {
-    const client: string[] = []
-    const name: string[] = []
-    const command: string[] = []
-    let dryRun = false
-    for (const arg of args) {
-        if (arg === '--dry-run' || arg === '-n') { dryRun = true; continue }
-        const m = arg.match(/^--(client|name|command)(?:=(.*))?$/)
-        if (!m) continue
-        const value = m[2]
-        if (value === undefined) continue
-        if (m[1] === 'client') value.split(',').filter(Boolean).forEach((v) => client.push(v.trim()))
-        if (m[1] === 'name') name.push(value)
-        if (m[1] === 'command') command.push(value)
-    }
-    return {
-        client: client.length > 0 ? client : undefined,
-        name: name.length > 0 ? name : undefined,
-        command: command.length > 0 ? command : undefined,
-        dryRun,
-    }
-}
-
-function buildEntryFromFlags(flags: ParsedFlags): McpServerEntry {
-    const command = flags.command?.[0] ?? defaultCommand()
-    return { command, args: [] }
+function entryForCli(flags: ParsedFlags): McpServerEntry {
+    return buildEntryFromFlags(flags, { command: defaultCommand() })
 }
 
 /**
diff --git a/src/mcp/install/flags.ts b/src/mcp/install/flags.ts
new file mode 100644
index 0000000..8e0ed7f
--- /dev/null
+++ b/src/mcp/install/flags.ts
@@ -0,0 +1,121 @@
+/**
+ * Flag parser for `agentmark-mcp install / setup / uninstall`.
+ *
+ * Extracted into a standalone module so tests can exercise the
+ * parser without importing `cli.ts` (which has top-level
+ * side effects: it spawns the MCP server on import).
+ *
+ * Supported flags:
+ *   --client=<id>     repeatable, comma-separable
+ *   --name=<name>     entry name (default: agentmark)
+ *   --command=<path>  command to register
+ *   --env=KEY=VALUE   env var for the registered server. Repeatable.
+ *   --dry-run | -n    no-op write
+ */
+import type { McpServerEntry } from './types'
+
+export interface ParsedFlags {
+    client: string[] | undefined
+    name: string[] | undefined
+    command: string[] | undefined
+    /** When supplied, the resolved env map. Empty object means
+     *  `--env` was used but every value parsed empty (still valid). */
+    env: Record<string, string> | undefined
+    dryRun: boolean
+}
+
+/**
+ * Env-var name shape. Restricted to identifier chars so a malformed
+ * `--env` can't be coerced into shell metacharacters that an MCP
+ * client's launcher might interpret. Mixed case allowed because some
+ * tools use them (e.g. `NodeEnv`).
+ */
+const ENV_KEY_PATTERN = /^[A-Za-z_][A-Za-z0-9_]*$/
+const ENV_VALUE_MAX_LEN = 4 * 1024
+
+export function parseFlags(args: string[], emit?: (line: string) => void): ParsedFlags {
+    const client: string[] = []
+    const name: string[] = []
+    const command: string[] = []
+    const env: Record<string, string> = {}
+    let envSeen = false
+    let dryRun = false
+    const warn = emit ?? ((line: string) => process.stderr.write(`${line}\n`))
+
+    for (const arg of args) {
+        if (arg === '--dry-run' || arg === '-n') { dryRun = true; continue }
+        const m = arg.match(/^--(client|name|command|env)(?:=(.*))?$/)
+        if (!m) continue
+        const value = m[2]
+        if (value === undefined) continue
+        if (m[1] === 'client') value.split(',').filter(Boolean).forEach((v) => client.push(v.trim()))
+        if (m[1] === 'name') name.push(value)
+        if (m[1] === 'command') command.push(value)
+        if (m[1] === 'env') {
+            const { key, value: envValue } = parseEnvFlag(value)
+            if (Object.prototype.hasOwnProperty.call(env, key)) {
+                warn(`warning: --env=${key}=… specified more than once; later value wins.`)
+            }
+            env[key] = envValue
+            envSeen = true
+        }
+    }
+
+    return {
+        client: client.length > 0 ? client : undefined,
+        name: name.length > 0 ? name : undefined,
+        command: command.length > 0 ? command : undefined,
+        env: envSeen ? env : undefined,
+        dryRun,
+    }
+}
+
+/**
+ * Parse one `KEY=value` pair. Throws on malformed input so a typo
+ * fails the install loudly instead of silently writing a broken
+ * config block to the user's AI client.
+ */
+export function parseEnvFlag(raw: string): { key: string; value: string } {
+    const idx = raw.indexOf('=')
+    if (idx < 1) {
+        throw new Error(
+            `--env must be in KEY=VALUE form (got "${raw}"). `
+            + 'Quote the whole pair if the value contains spaces.',
+        )
+    }
+    const key = raw.slice(0, idx)
+    const value = raw.slice(idx + 1)
+    if (!ENV_KEY_PATTERN.test(key)) {
+        throw new Error(
+            `--env key "${key}" is not a valid env-var name. `
+            + 'Must match [A-Za-z_][A-Za-z0-9_]*.',
+        )
+    }
+    if (value.length > ENV_VALUE_MAX_LEN) {
+        throw new Error(
+            `--env value for "${key}" exceeds ${ENV_VALUE_MAX_LEN} chars. `
+            + 'Use a credential reference instead of inlining a long secret.',
+        )
+    }
+    if (value.indexOf('\0') !== -1) {
+        throw new Error(`--env value for "${key}" contains a null byte; rejected.`)
+    }
+    return { key, value }
+}
+
+/**
+ * Compose an {@link McpServerEntry} from parsed flags. `command`
+ * defaults to whatever the caller resolves; passing it in keeps
+ * this module pure (no PATH lookups, no fs).
+ */
+export function buildEntryFromFlags(
+    flags: ParsedFlags,
+    defaults: { command: string },
+): McpServerEntry {
+    const command = flags.command?.[0] ?? defaults.command
+    const entry: McpServerEntry = { command, args: [] }
+    if (flags.env && Object.keys(flags.env).length > 0) {
+        entry.env = flags.env
+    }
+    return entry
+}
diff --git a/test/mcp/install-flags.test.ts b/test/mcp/install-flags.test.ts
new file mode 100644
index 0000000..bf09ecf
--- /dev/null
+++ b/test/mcp/install-flags.test.ts
@@ -0,0 +1,165 @@
+/**
+ * Tests for the install-CLI flag parser.
+ *
+ * Focus on the new `--env=KEY=VALUE` surface introduced for the
+ * ThinkFleet Memory Bridge — it carries credentials into the AI
+ * client's MCP config, so malformed input must fail loud and the
+ * happy path must produce exactly the McpServerEntry shape the
+ * downstream writer expects.
+ */
+import { describe, it, expect } from 'vitest'
+import {
+    parseFlags,
+    parseEnvFlag,
+    buildEntryFromFlags,
+} from '../../src/mcp/install/flags'
+
+describe('parseEnvFlag', () => {
+    it('parses a simple KEY=VALUE pair', () => {
+        expect(parseEnvFlag('FOO=bar')).toEqual({ key: 'FOO', value: 'bar' })
+    })
+
+    it('preserves "=" signs inside the value (e.g. base64)', () => {
+        expect(parseEnvFlag('TOKEN=abc=def==')).toEqual({
+            key: 'TOKEN',
+            value: 'abc=def==',
+        })
+    })
+
+    it('allows empty values', () => {
+        expect(parseEnvFlag('FLAG=')).toEqual({ key: 'FLAG', value: '' })
+    })
+
+    it('rejects missing "=" entirely', () => {
+        expect(() => parseEnvFlag('NOEQUALS')).toThrowError(/KEY=VALUE form/)
+    })
+
+    it('rejects "=value" without a key', () => {
+        expect(() => parseEnvFlag('=oops')).toThrowError(/KEY=VALUE form/)
+    })
+
+    it('rejects keys with shell-relevant characters', () => {
+        expect(() => parseEnvFlag('FOO;rm=anything')).toThrowError(/not a valid env-var name/)
+        expect(() => parseEnvFlag('FOO BAR=x')).toThrowError(/not a valid env-var name/)
+        expect(() => parseEnvFlag('FOO`x`=y')).toThrowError(/not a valid env-var name/)
+    })
+
+    it('rejects keys starting with a digit', () => {
+        expect(() => parseEnvFlag('1FOO=bar')).toThrowError(/not a valid env-var name/)
+    })
+
+    it('accepts mixed-case keys (NodeEnv-style)', () => {
+        expect(parseEnvFlag('NodeEnv=production')).toEqual({
+            key: 'NodeEnv',
+            value: 'production',
+        })
+    })
+
+    it('rejects values containing a null byte', () => {
+        expect(() => parseEnvFlag('FOO=before\0after')).toThrowError(/null byte/)
+    })
+
+    it('rejects values over the 4KB cap', () => {
+        const big = 'x'.repeat(4 * 1024 + 1)
+        expect(() => parseEnvFlag(`FOO=${big}`)).toThrowError(/exceeds 4096/)
+    })
+})
+
+describe('parseFlags — --env', () => {
+    it('returns env undefined when no --env was passed', () => {
+        const flags = parseFlags(['--client=cursor'])
+        expect(flags.env).toBeUndefined()
+    })
+
+    it('captures a single --env=KEY=VAL', () => {
+        const flags = parseFlags(['--env=THINKFLEET_API_KEY=sk-abc'])
+        expect(flags.env).toEqual({ THINKFLEET_API_KEY: 'sk-abc' })
+    })
+
+    it('captures multiple --env flags in order', () => {
+        const flags = parseFlags([
+            '--env=THINKFLEET_BASE_URL=https://app.thinkfleet.ai',
+            '--env=THINKFLEET_PROJECT_ID=proj_test',
+            '--env=THINKFLEET_API_KEY=sk-test',
+        ])
+        expect(flags.env).toEqual({
+            THINKFLEET_BASE_URL: 'https://app.thinkfleet.ai',
+            THINKFLEET_PROJECT_ID: 'proj_test',
+            THINKFLEET_API_KEY: 'sk-test',
+        })
+    })
+
+    it('lets a later --env override an earlier one and warns on stderr', () => {
+        const warnings: string[] = []
+        const flags = parseFlags(
+            ['--env=THINKFLEET_API_KEY=sk-old', '--env=THINKFLEET_API_KEY=sk-new'],
+            (l) => warnings.push(l),
+        )
+        expect(flags.env).toEqual({ THINKFLEET_API_KEY: 'sk-new' })
+        expect(warnings.length).toBe(1)
+        expect(warnings[0]).toContain('THINKFLEET_API_KEY')
+        expect(warnings[0]).toContain('more than once')
+    })
+
+    it('warning lines NEVER contain the env values (secret-safe)', () => {
+        const warnings: string[] = []
+        parseFlags(
+            ['--env=APIKEY=sk-very-secret-original', '--env=APIKEY=sk-equally-secret-replacement'],
+            (l) => warnings.push(l),
+        )
+        const joined = warnings.join('\n')
+        expect(joined).not.toContain('sk-very-secret-original')
+        expect(joined).not.toContain('sk-equally-secret-replacement')
+    })
+
+    it('coexists with the other flags', () => {
+        const flags = parseFlags([
+            '--client=claude-code,cursor',
+            '--env=A=1',
+            '--name=thinkfleet',
+            '--dry-run',
+        ])
+        expect(flags.client).toEqual(['claude-code', 'cursor'])
+        expect(flags.env).toEqual({ A: '1' })
+        expect(flags.name).toEqual(['thinkfleet'])
+        expect(flags.dryRun).toBe(true)
+    })
+
+    it('throws (propagates parseEnvFlag error) on a malformed --env', () => {
+        expect(() => parseFlags(['--env=NOEQ'])).toThrowError(/KEY=VALUE form/)
+    })
+
+    it('returns env as an empty object when --env was used but only empty-value pairs were supplied', () => {
+        // Edge case: `--env=FLAG=` is legal and means "set FLAG to empty string".
+        const flags = parseFlags(['--env=FLAG='])
+        expect(flags.env).toEqual({ FLAG: '' })
+    })
+})
+
+describe('buildEntryFromFlags', () => {
+    it('uses the default command when --command is absent', () => {
+        const flags = parseFlags([])
+        const entry = buildEntryFromFlags(flags, { command: '/opt/agentmark/bin/agentmark-mcp' })
+        expect(entry.command).toBe('/opt/agentmark/bin/agentmark-mcp')
+        expect(entry.args).toEqual([])
+        expect(entry.env).toBeUndefined()
+    })
+
+    it('honors --command when supplied', () => {
+        const flags = parseFlags(['--command=/usr/local/bin/agentmark-mcp'])
+        const entry = buildEntryFromFlags(flags, { command: '/should/not/be/used' })
+        expect(entry.command).toBe('/usr/local/bin/agentmark-mcp')
+    })
+
+    it('populates entry.env from parsed flags', () => {
+        const flags = parseFlags(['--env=A=1', '--env=B=2'])
+        const entry = buildEntryFromFlags(flags, { command: '/opt/agentmark/bin/agentmark-mcp' })
+        expect(entry.env).toEqual({ A: '1', B: '2' })
+    })
+
+    it('omits entry.env when no --env was supplied (clean JSON)', () => {
+        const entry = buildEntryFromFlags(parseFlags([]), { command: '/x' })
+        // Strict undefined — the writer's JSON serializer will skip it.
+        expect(entry.env).toBeUndefined()
+    })
+})
diff --git a/test/mcp/install.test.ts b/test/mcp/install.test.ts
index b2f4769..a1a3525 100644
--- a/test/mcp/install.test.ts
+++ b/test/mcp/install.test.ts
@@ -129,6 +129,37 @@ describe('Fake client end-to-end — apply + remove', () => {
         expect(written).toEqual({ mcpServers: { agentmark: ENTRY } })
     })
 
+    it('writes the env block when the entry carries env vars', async () => {
+        const client = fakeClient('test-a-env', 'a-env.json')
+        const envEntry: McpServerEntry = {
+            command: '/opt/thinkfleet/agentmark/bin/agentmark-mcp',
+            args: [],
+            env: {
+                THINKFLEET_BASE_URL: 'https://app.thinkfleet.ai',
+                THINKFLEET_PROJECT_ID: 'proj_test',
+                THINKFLEET_API_KEY: 'sk-test-token',
+            },
+        }
+        await applyToFake(client, envEntry)
+        const written = JSON.parse(await readFile(client.configPath()!, 'utf8'))
+        expect(written.mcpServers.agentmark.env).toEqual(envEntry.env)
+    })
+
+    it('updates the env block when the install is re-run with new values', async () => {
+        const client = fakeClient('test-a-rotate', 'a-rotate.json')
+        await applyToFake(client, {
+            command: '/x', args: [],
+            env: { THINKFLEET_API_KEY: 'sk-old' },
+        })
+        const second = await applyToFake(client, {
+            command: '/x', args: [],
+            env: { THINKFLEET_API_KEY: 'sk-new' },
+        })
+        expect(second.action).toBe('updated')
+        const written = JSON.parse(await readFile(client.configPath()!, 'utf8'))
+        expect(written.mcpServers.agentmark.env.THINKFLEET_API_KEY).toBe('sk-new')
+    })
+
     it('preserves unrelated keys (mcp + other) in the config', async () => {
         const client = fakeClient('test-b', 'b.json')
         await writeJson(client.configPath()!, {