diff --git a/src/plugin-config.test.ts b/src/plugin-config.test.ts
index c8bac63ba..fbe4d8599 100644
--- a/src/plugin-config.test.ts
+++ b/src/plugin-config.test.ts
@@ -560,7 +560,6 @@ describe("loadPluginConfig", () => {
       git_env_prefix: "GIT_MASTER=1",
     })
   })
-
   describe("team_mode.tmux_visualization", () => {
     it("#given canonical user config enables team_mode and legacy config also exists #when loadPluginConfig runs #then tmux_visualization remains false", async () => {
       // given
@@ -639,4 +638,201 @@ describe("loadPluginConfig", () => {
       expect(config.team_mode).toBeUndefined()
     })
   })
+
+  it("should merge configs from ancestor directories with closer winning", async () => {
+    // given
+    const rootDir = mkdtempSync(join(tmpdir(), "omo-plugin-config-walk-"))
+    const userConfigDir = join(rootDir, "user-config")
+    const homeDir = join(rootDir, "home")
+    const workDir = join(homeDir, "work")
+    const projectDir = join(workDir, "project")
+
+    tempDirs.push(rootDir)
+    mkdirSync(userConfigDir, { recursive: true })
+    mkdirSync(join(homeDir, ".opencode"), { recursive: true })
+    mkdirSync(join(workDir, ".opencode"), { recursive: true })
+    mkdirSync(join(projectDir, ".opencode"), { recursive: true })
+
+    writeFileSync(
+      join(userConfigDir, "oh-my-openagent.jsonc"),
+      JSON.stringify({ agents: { oracle: { model: "user/model" } } })
+    )
+    writeFileSync(
+      join(homeDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ agents: { oracle: { model: "home/model" } } })
+    )
+    writeFileSync(
+      join(workDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ agents: { oracle: { model: "work/model" } } })
+    )
+    writeFileSync(
+      join(projectDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ agents: { oracle: { model: "project/model" } } })
+    )
+
+    process.env.OPENCODE_CONFIG_DIR = userConfigDir
+    process.env.HOME = homeDir
+
+    // when
+    const { loadPluginConfig } = await importFreshPluginConfigModule()
+    const config = loadPluginConfig(projectDir, {})
+
+    // then
+    expect(config.agents?.oracle?.model).toBe("project/model")
+  })
+
+  it("should layer ancestor configs so each contributes fields not overridden by closer ones", async () => {
+    // given
+    const rootDir = mkdtempSync(join(tmpdir(), "omo-plugin-config-walk-layer-"))
+    const userConfigDir = join(rootDir, "user-config")
+    const homeDir = join(rootDir, "home")
+    const workDir = join(homeDir, "work")
+    const projectDir = join(workDir, "project")
+
+    tempDirs.push(rootDir)
+    mkdirSync(userConfigDir, { recursive: true })
+    mkdirSync(join(homeDir, ".opencode"), { recursive: true })
+    mkdirSync(join(workDir, ".opencode"), { recursive: true })
+    mkdirSync(join(projectDir, ".opencode"), { recursive: true })
+
+    writeFileSync(join(userConfigDir, "oh-my-openagent.jsonc"), "{}")
+    writeFileSync(
+      join(homeDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ agents: { oracle: { model: "home/oracle" } } })
+    )
+    writeFileSync(
+      join(workDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ agents: { hephaestus: { model: "work/hephaestus" } } })
+    )
+    writeFileSync(
+      join(projectDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ agents: { sisyphus: { model: "project/sisyphus" } } })
+    )
+
+    process.env.OPENCODE_CONFIG_DIR = userConfigDir
+    process.env.HOME = homeDir
+
+    // when
+    const { loadPluginConfig } = await importFreshPluginConfigModule()
+    const config = loadPluginConfig(projectDir, {})
+
+    // then - each level contributes a non-conflicting field
+    expect(config.agents?.oracle?.model).toBe("home/oracle")
+    expect(config.agents?.hephaestus?.model).toBe("work/hephaestus")
+    expect(config.agents?.sisyphus?.model).toBe("project/sisyphus")
+  })
+
+  it("should preserve mcp_env_allowlist as user-only when ancestors set their own allowlists", async () => {
+    // given
+    const rootDir = mkdtempSync(join(tmpdir(), "omo-plugin-config-walk-allowlist-"))
+    const userConfigDir = join(rootDir, "user-config")
+    const homeDir = join(rootDir, "home")
+    const workDir = join(homeDir, "work")
+    const projectDir = join(workDir, "project")
+
+    tempDirs.push(rootDir)
+    mkdirSync(userConfigDir, { recursive: true })
+    mkdirSync(join(homeDir, ".opencode"), { recursive: true })
+    mkdirSync(join(workDir, ".opencode"), { recursive: true })
+    mkdirSync(join(projectDir, ".opencode"), { recursive: true })
+
+    writeFileSync(
+      join(userConfigDir, "oh-my-openagent.jsonc"),
+      JSON.stringify({ mcp_env_allowlist: ["USER_ONLY_TOKEN"] })
+    )
+    writeFileSync(
+      join(homeDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ mcp_env_allowlist: ["HOME_TOKEN"] })
+    )
+    writeFileSync(
+      join(workDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ mcp_env_allowlist: ["WORK_TOKEN"] })
+    )
+    writeFileSync(
+      join(projectDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ mcp_env_allowlist: ["PROJECT_TOKEN"] })
+    )
+
+    process.env.OPENCODE_CONFIG_DIR = userConfigDir
+    process.env.HOME = homeDir
+
+    // when
+    const { loadPluginConfig } = await importFreshPluginConfigModule()
+    const config = loadPluginConfig(projectDir, {})
+
+    // then - only the canonical user config can extend the allowlist
+    expect(config.mcp_env_allowlist).toEqual(["USER_ONLY_TOKEN"])
+  })
+
+  it("should stop walking at $HOME and ignore configs above it", async () => {
+    // given
+    const rootDir = mkdtempSync(join(tmpdir(), "omo-plugin-config-walk-stop-"))
+    const userConfigDir = join(rootDir, "user-config")
+    const aboveHomeDir = join(rootDir, "above-home")
+    const homeDir = join(aboveHomeDir, "home")
+    const projectDir = join(homeDir, "project")
+
+    tempDirs.push(rootDir)
+    mkdirSync(userConfigDir, { recursive: true })
+    mkdirSync(join(aboveHomeDir, ".opencode"), { recursive: true })
+    mkdirSync(join(homeDir, ".opencode"), { recursive: true })
+    mkdirSync(join(projectDir, ".opencode"), { recursive: true })
+
+    writeFileSync(join(userConfigDir, "oh-my-openagent.jsonc"), "{}")
+    writeFileSync(
+      join(aboveHomeDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ agents: { oracle: { model: "above-home/leak" } } })
+    )
+    writeFileSync(
+      join(homeDir, ".opencode", "oh-my-openagent.jsonc"),
+      JSON.stringify({ agents: { hephaestus: { model: "home/wins" } } })
+    )
+    writeFileSync(join(projectDir, ".opencode", "oh-my-openagent.jsonc"), "{}")
+
+    process.env.OPENCODE_CONFIG_DIR = userConfigDir
+    process.env.HOME = homeDir
+
+    // when
+    const { loadPluginConfig } = await importFreshPluginConfigModule()
+    const config = loadPluginConfig(projectDir, {})
+
+    // then - $HOME's config applies, but the directory above it does NOT
+    expect(config.agents?.hephaestus?.model).toBe("home/wins")
+    expect(config.agents?.oracle).toBeUndefined()
+  })
+
+  it("should migrate legacy basenames found in ancestor directories", async () => {
+    // given
+    const rootDir = mkdtempSync(join(tmpdir(), "omo-plugin-config-walk-legacy-"))
+    const userConfigDir = join(rootDir, "user-config")
+    const homeDir = join(rootDir, "home")
+    const workDir = join(homeDir, "work")
+    const projectDir = join(workDir, "project")
+    const ancestorLegacyPath = join(workDir, ".opencode", "oh-my-opencode.jsonc")
+    const ancestorCanonicalPath = join(workDir, ".opencode", "oh-my-openagent.jsonc")
+
+    tempDirs.push(rootDir)
+    mkdirSync(userConfigDir, { recursive: true })
+    mkdirSync(join(homeDir, ".opencode"), { recursive: true })
+    mkdirSync(join(workDir, ".opencode"), { recursive: true })
+    mkdirSync(join(projectDir, ".opencode"), { recursive: true })
+
+    writeFileSync(join(userConfigDir, "oh-my-openagent.jsonc"), "{}")
+    writeFileSync(
+      ancestorLegacyPath,
+      JSON.stringify({ agents: { oracle: { model: "ancestor-legacy/model" } } })
+    )
+
+    process.env.OPENCODE_CONFIG_DIR = userConfigDir
+    process.env.HOME = homeDir
+
+    // when
+    const { loadPluginConfig } = await importFreshPluginConfigModule()
+    const config = loadPluginConfig(projectDir, {})
+
+    // then
+    expect(existsSync(ancestorLegacyPath)).toBe(false)
+    expect(existsSync(ancestorCanonicalPath)).toBe(true)
+    expect(config.agents?.oracle?.model).toBe("ancestor-legacy/model")
+  })
 })
diff --git a/src/plugin-config.ts b/src/plugin-config.ts
index 008c7cd09..f745f9181 100644
--- a/src/plugin-config.ts
+++ b/src/plugin-config.ts
@@ -1,4 +1,5 @@
 import * as fs from "fs";
+import { homedir } from "node:os";
 import * as path from "path";
 import { OhMyOpenCodeConfigSchema, type OhMyOpenCodeConfig } from "./config";
 import {
@@ -8,12 +9,41 @@ import {
   addConfigLoadError,
   parseJsonc,
   detectPluginConfigFile,
+  findProjectOpencodePluginConfigFiles,
   migrateConfigFile,
   resolveAgentDefinitionPaths,
 } from "./shared";
 import { migrateLegacyConfigFile } from "./shared/migrate-legacy-config-file";
 import { CONFIG_BASENAME, LEGACY_CONFIG_BASENAME } from "./shared/plugin-identity";
 
+function resolveHomeDirectory(): string {
+  // Read env vars directly to bypass os.homedir() caching. Bun caches the
+  // first os.homedir() result, which means tests that set process.env.HOME
+  // after import never see the new value. Production behaviour is preserved
+  // because HOME (or USERPROFILE on Windows) is set by the OS at startup.
+  return process.env.HOME ?? process.env.USERPROFILE ?? homedir()
+}
+
+function migrateLegacyAndResolveCanonicalPath(detectedPath: string): string {
+  if (!path.basename(detectedPath).startsWith(LEGACY_CONFIG_BASENAME)) {
+    return detectedPath
+  }
+
+  const migrated = migrateLegacyConfigFile(detectedPath)
+  const canonicalPath = path.join(
+    path.dirname(detectedPath),
+    `${CONFIG_BASENAME}${path.extname(detectedPath)}`,
+  )
+
+  // Only switch to canonical path if migration succeeded OR canonical file already exists
+  if (migrated || fs.existsSync(canonicalPath)) {
+    return canonicalPath
+  }
+
+  // Otherwise keep loading from the legacy path that was detected
+  return detectedPath
+}
+
 function loadExplicitGitMasterOverrides(configPath: string): Record<string, unknown> | undefined {
   try {
     if (!fs.existsSync(configPath)) {
@@ -214,47 +244,35 @@ export function loadPluginConfig(
   }
 
   // Auto-copy legacy config file to canonical name if needed
-  if (userDetected.format !== "none" && path.basename(userDetected.path).startsWith(LEGACY_CONFIG_BASENAME)) {
-    const migrated = migrateLegacyConfigFile(userDetected.path);
-    const canonicalPath = path.join(
-      path.dirname(userDetected.path),
-      `${CONFIG_BASENAME}${path.extname(userDetected.path)}`
-    );
-    // Only switch to canonical path if migration succeeded OR canonical file already exists
-    if (migrated || fs.existsSync(canonicalPath)) {
-      userConfigPath = canonicalPath;
+  if (userDetected.format !== "none") {
+    userConfigPath = migrateLegacyAndResolveCanonicalPath(userConfigPath)
+  }
+
+  // Walk up from directory to $HOME for ancestor configs (closest first)
+  // This subsumes the previous single project-config load: the closest hit is
+  // the project's own .opencode/oh-my-openagent.json[c], and walking continues
+  // up so configs in ~/work/ (etc.) apply to all subprojects.
+  const ancestorConfigPaths = findProjectOpencodePluginConfigFiles(
+    directory,
+    resolveHomeDirectory(),
+  )
+  log("Walked ancestor plugin configs", {
+    paths: ancestorConfigPaths,
+    count: ancestorConfigPaths.length,
+  })
+
+  // Migrate any legacy basenames among ancestors and warn on dual-config presence
+  const canonicalAncestorPaths = ancestorConfigPaths.map((ancestorPath) => {
+    const opencodeDir = path.dirname(ancestorPath)
+    const ancestorDetected = detectPluginConfigFile(opencodeDir)
+    if (ancestorDetected.legacyPath) {
+      log("Canonical plugin config detected alongside legacy config. Remove the legacy file to avoid confusion.", {
+        canonicalPath: ancestorDetected.path,
+        legacyPath: ancestorDetected.legacyPath,
+      })
     }
-    // Otherwise keep loading from the legacy path that was detected
-  }
-
-  // Project-level config path - prefer .jsonc over .json
-  const projectBasePath = path.join(directory, ".opencode");
-  const projectDetected = detectPluginConfigFile(projectBasePath);
-  let projectConfigPath =
-    projectDetected.format !== "none"
-      ? projectDetected.path
-      : path.join(projectBasePath, `${CONFIG_BASENAME}.json`);
-
-  if (projectDetected.legacyPath) {
-    log("Canonical plugin config detected alongside legacy config. Remove the legacy file to avoid confusion.", {
-      canonicalPath: projectDetected.path,
-      legacyPath: projectDetected.legacyPath,
-    });
-  }
-
-  // Auto-copy legacy project config file to canonical name if needed
-  if (projectDetected.format !== "none" && path.basename(projectDetected.path).startsWith(LEGACY_CONFIG_BASENAME)) {
-    const projectMigrated = migrateLegacyConfigFile(projectDetected.path);
-    const canonicalProjectPath = path.join(
-      path.dirname(projectDetected.path),
-      `${CONFIG_BASENAME}${path.extname(projectDetected.path)}`
-    );
-    // Only switch to canonical path if migration succeeded OR canonical file already exists
-    if (projectMigrated || fs.existsSync(canonicalProjectPath)) {
-      projectConfigPath = canonicalProjectPath;
-    }
-    // Otherwise keep loading from the legacy path that was detected
-  }
+    return migrateLegacyAndResolveCanonicalPath(ancestorPath)
+  })
 
   // Load user config first (base). Parse empty config through Zod to apply field defaults.
   const userConfig = loadConfigFromPath(userConfigPath, ctx)
@@ -271,34 +289,52 @@ export function loadPluginConfig(
   let config: OhMyOpenCodeConfig =
     userConfig ?? OhMyOpenCodeConfigSchema.parse({});
 
-  // Override with project config
+  // Merge ancestor configs from farthest to nearest, so closer overrides farther.
+  // Walker returns nearest-first; reverse for merge order.
   const defaultGitMaster = OhMyOpenCodeConfigSchema.parse({}).git_master
-  const projectConfig = loadConfigFromPath(projectConfigPath, ctx);
-  const projectGitMasterOverrides = loadExplicitGitMasterOverrides(projectConfigPath)
+  const ancestorGitMasterOverrides: Array<Record<string, unknown>> = []
 
-  if (projectConfig?.agent_definitions) {
-    projectConfig.agent_definitions = resolveAgentDefinitionPaths(
-      projectConfig.agent_definitions,
-      projectBasePath,
-      directory
-    )
+  for (const ancestorPath of canonicalAncestorPaths.slice().reverse()) {
+    const ancestorConfig = loadConfigFromPath(ancestorPath, ctx)
+    const ancestorOverrides = loadExplicitGitMasterOverrides(ancestorPath)
+
+    if (ancestorConfig?.agent_definitions) {
+      // Resolve relative paths against this ancestor's own .opencode/ base.
+      const ancestorBasePath = path.dirname(ancestorPath)
+      const ancestorDir = path.dirname(ancestorBasePath)
+      ancestorConfig.agent_definitions = resolveAgentDefinitionPaths(
+        ancestorConfig.agent_definitions,
+        ancestorBasePath,
+        ancestorDir,
+      )
+    }
+
+    if (ancestorConfig) {
+      config = mergeConfigs(config, ancestorConfig)
+    }
+
+    if (ancestorOverrides) {
+      ancestorGitMasterOverrides.push(ancestorOverrides)
+    }
   }
 
-  if (projectConfig) {
-    config = mergeConfigs(config, projectConfig);
-  }
-
-  if (userGitMasterOverrides || projectGitMasterOverrides) {
+  if (userGitMasterOverrides || ancestorGitMasterOverrides.length > 0) {
     config = {
       ...config,
       git_master: {
         ...defaultGitMaster,
         ...(userGitMasterOverrides ?? {}),
-        ...(projectGitMasterOverrides ?? {}),
+        // Ancestors are pushed far-to-near; Object.assign with an empty seed
+        // applies each in order so the nearest (last) wins.
+        ...Object.assign({}, ...ancestorGitMasterOverrides),
       },
     }
   }
 
+  // Security: mcp_env_allowlist remains user-only across the entire walk.
+  // This prevents clone-and-load attacks where a malicious project (or any
+  // walked ancestor) could extend the env var allowlist used during ${VAR}
+  // expansion in .mcp.json files. See commit 316d2504 for context.
   config = {
     ...config,
     mcp_env_allowlist: userConfig?.mcp_env_allowlist ?? [],