/**
 * dsh-slopo — slopo as a DeepSeek Harness bundle.
 *
 * Three contributions:
 *
 *   1. Three skills on `ctx.skills`, ported from slopo's own agent configs.
 *      All three are user-invocable and deliberately NOT model-invocable,
 *      matching upstream: every one of these commands can spend minutes
 *      embedding, so the human decides when.
 *   2. The `dsh-slopo` configuration: this module's own exported `Config`, which
 *      the framework projects onto the Loader entry that composed it and
 *      addresses by that entry's id. Nothing is registered for it — a section
 *      assembled from a schema cannot disagree with the schema — and the page
 *      that edits it lives in `client/client.js`.
 *   3. One `slopo` tool that resolves the CLI, materialises the config, and
 *      runs the long work as a background job.
 *
 * Why `ctx.inject(['settings'], ...)` rather than `inject: ['settings']`: a
 * Cordis plugin with an unsatisfied required dependency never runs `apply` at
 * all. Putting `settings` in the top-level inject would make the tool and the
 * skills disappear on any profile without a settings provider, which is a
 * silent whole-plugin failure for an optional capability. The optional form
 * simply has nowhere to persist a `configure` and says so.
 *
 * Plain ESM, no build step — deliberately. `dsh plugin add git+...` fetches the
 * source tree, not build output, and a `prepare` script would make every user
 * allowlist a build before the first install succeeds.
 */

import { existsSync } from 'node:fs'
import { mkdir, readFile, writeFile } from 'node:fs/promises'
import { join, sep } from 'node:path'
import { fileURLToPath } from 'node:url'

import { defineTool } from '@deepseek-ai/dsh-tools'
import Schema from '@deepseek-ai/schemastery'

import { missingRequired, normalizeConfig, renderSlopoConfig } from './lib/config.js'
import { probeEmbeddingEndpoint } from './lib/probe.js'
import { toJsonValue } from './lib/json.js'
import {
  budgetRemedy,
  checkBudget,
  effectiveExcludes,
  parseIndexOutput,
  readIndexCounts,
} from './lib/scope.js'
import {
  resolveDshHome,
  workspaceStateDir,
} from './lib/paths.js'
import {
  explainFailure,
  findSlopo,
  installEnv,
  lastLogError,
  commandLine,
  runShell,
  slopoArgs,
  uvInstallArgs,
} from './lib/slopo.js'

/** Rank of a packaged bundle's skills. Hardcoded, not imported. */
const BUNDLED_SKILL_RANK = 600

/** Reserved provider name inside dsh; registering it throws. */
const PROVIDER_NAME = 'dsh-slopo'

/** Settings namespace. Must match /^[a-z][a-z0-9-]*$/. */
const SETTINGS_NAMESPACE = 'dsh-slopo'

const SKILL_NAMES = ['slopo-review', 'slopo-analyze-ignore', 'slopo-analyze-one']

const SKILLS_DIR = fileURLToPath(new URL('./skills/', import.meta.url))

/** Long-running actions, in the order the tool description advertises them. */
/**
 * Actions that default to a background job.
 *
 * Only the warm-up. `index` plus `embed` is the long, watchable step — the one
 * the user asked to be able to watch — while a review finds a warm index and
 * returns its report directly. Named after dsh-tool-bash's `run_in_background`,
 * because a model's prior is that backgrounding is something it ASKS for rather
 * than the default.
 */
const BACKGROUND_BY_DEFAULT = new Set(['prepare'])

/** Every configuration field this plugin exposes. */
const SETTING_KEYS = [
  'binary',
  'autoInstall',
  'embeddingModel',
  'embeddingDimensions',
  'embeddingApiBase',
  'embeddingApiKey',
  'embeddingParamsJson',
  'sourceDir',
  'sourceDirExclude',
  'useDefaultExcludes',
  'maxIndexUnits',
  'ignoreFile',
  'stateDir',
  'embeddingRequestDelay',
  'timeoutMs',
]

/**
 * The plugin's composition schema.
 *
 * Nothing meaningful is defaulted: slopo itself requires `source_dir`,
 * `embedding_model` and `embedding_dimensions`, and guessing an embedding
 * backend would mean guessing where money is spent. Unset means unset, and the
 * tool says so.
 *
 * Every field is marked `volatile()`, which is what puts it on the settings
 * page: the framework's form projection keeps only the fields whose nearest
 * volatile ancestor makes them editable without remounting the plugin, and an
 * entry with no such field is dropped from `settings.describe` entirely. An
 * unmarked field would still be *configurable* through the profile patch — it
 * would simply be invisible to every settings UI.
 *
 * `embeddingApiKey` additionally carries `role('secret')`, so the settings
 * wire never carries it: every remote read is redacted (`secrets` reports only
 * whether a value is set) and the browser sends the key one way, on write.
 */
export const Config = Schema.object({
  /** Explicit slopo executable. Empty means autodiscover. */
  binary: Schema.string().default('').volatile(),
  /** Install slopo into $DSH_HOME with uv when it is missing. */
  autoInstall: Schema.boolean().default(true).volatile(),
  /** LiteLLM model string, e.g. `ollama/jina-embeddings-v2-base-code:latest`. */
  embeddingModel: Schema.string().default('').volatile(),
  /** Output dimensions, which must match the model. */
  embeddingDimensions: Schema.number().default(0).volatile(),
  /** Provider base URL, e.g. `http://127.0.0.1:11434` for Ollama. */
  embeddingApiBase: Schema.string().default('').volatile(),
  /** Provider key. Passed to slopo in its environment, never written to disk. */
  embeddingApiKey: Schema.string().default('').role('secret').volatile(),
  /** Extra LiteLLM embedding params, as a JSON object string. */
  embeddingParamsJson: Schema.string().default('{}').volatile(),
  /** Code to index. Empty means the session's working directory. */
  sourceDir: Schema.string().default('').volatile(),
  /** Extra gitignore-style paths to skip, on top of the defaults. */
  sourceDirExclude: Schema.array(String).default([]).volatile(),
  /** Exclude vendored dependencies and build output. Off means slopo sees everything. */
  useDefaultExcludes: Schema.boolean().default(true).volatile(),
  /** Refuse to embed more than this many units without being asked. 0 removes the limit. */
  maxIndexUnits: Schema.number().default(5000).volatile(),
  /** Ignore file. Empty means inside the per-workspace state directory. */
  ignoreFile: Schema.string().default('').volatile(),
  /** State directory. Empty means $DSH_HOME/dsh-slopo/workspaces/<workspace>. */
  stateDir: Schema.string().default('').volatile(),
  /** Milliseconds between embedding requests, for rate-limited providers. */
  embeddingRequestDelay: Schema.number().default(0).volatile(),
  /** Cooperative budget for a foreground slopo run. */
  timeoutMs: Schema.number().default(600_000).volatile(),
})

/** Resolve the harness home, preferring the harness's own resolver. */
function dshHomeOf(ctx) {
  try {
    const homePath = ctx.get('dshHomePath')
    if (typeof homePath === 'function') {
      const resolved = homePath()
      if (typeof resolved === 'string' && resolved !== '') return resolved
    }
  } catch {
    // The service is declared optional; absence is expected outside dsh-app-boot.
  }
  return resolveDshHome()
}

/** Every path one workspace's slopo state occupies. */
export function workspacePaths(dshHome, cwd, settings) {
  const stateDir =
    typeof settings.stateDir === 'string' && settings.stateDir.trim() !== ''
      ? settings.stateDir.trim()
      : workspaceStateDir(dshHome, cwd)
  return {
    stateDir,
    cwd,
    sourceDir: typeof settings.sourceDir === 'string' && settings.sourceDir.trim() !== ''
      ? settings.sourceDir.trim()
      : cwd,
    configPath: join(stateDir, 'slopo.conf.yaml'),
    dbFile: join(stateDir, 'slopo.db'),
    reportDir: join(stateDir, 'report'),
    ignoreFile:
      typeof settings.ignoreFile === 'string' && settings.ignoreFile.trim() !== ''
        ? settings.ignoreFile.trim()
        : join(stateDir, 'slopo.ignore.txt'),
    logFile: join(stateDir, 'slopo.agent.log'),
  }
}

/** Parse the JSON params field, tolerating an unset or malformed value. */
function embeddingParams(settings, problems) {
  const raw = typeof settings.embeddingParamsJson === 'string' ? settings.embeddingParamsJson.trim() : ''
  const params = {}
  if (raw !== '' && raw !== '{}') {
    try {
      const parsed = JSON.parse(raw)
      if (parsed === null || typeof parsed !== 'object' || Array.isArray(parsed)) {
        problems.push('embeddingParamsJson must be a JSON object')
      } else {
        Object.assign(params, parsed)
      }
    } catch (error) {
      problems.push(`embeddingParamsJson is not valid JSON: ${error.message}`)
    }
  }
  const apiBase = typeof settings.embeddingApiBase === 'string' ? settings.embeddingApiBase.trim() : ''
  if (apiBase !== '') params.api_base = apiBase
  return params
}

/**
 * Map this plugin's settings onto slopo's own key names.
 *
 * The names differ on purpose: dsh settings are camelCase by convention while
 * slopo's config file is snake_case, and slopo treats an unknown key as a hard
 * error, so this mapping is the only place a name can go wrong.
 */
export function toSlopoConfig(settings, paths, problems = []) {
  const config = {
    source_dir: paths.sourceDir,
    source_dir_exclude: effectiveExcludes(settings),
    db_file: paths.dbFile,
    report_dir: paths.reportDir,
    ignore_file: paths.ignoreFile,
    agent_log_file: paths.logFile,
    embedding_model: typeof settings.embeddingModel === 'string' ? settings.embeddingModel.trim() : '',
    // Omitted rather than written as 0 when unset: slopo requires a positive
    // integer, and pruneConfig drops an undefined value entirely.
    embedding_dimensions: Number(settings.embeddingDimensions) > 0 ? Number(settings.embeddingDimensions) : undefined,
    embedding_params: embeddingParams(settings, problems),
    embedding_request_delay: Number(settings.embeddingRequestDelay) || 0,
  }
  const { config: normalized, problems: numericProblems } = normalizeConfig(config)
  problems.push(...numericProblems)
  delete normalized.embedding_api_key
  return normalized
}

/** Read the `description:` line out of a SKILL.md frontmatter block. */
export function readDescription(body) {
  const frontmatter = /^---\r?\n([\s\S]*?)\r?\n---/.exec(body)
  if (frontmatter === null) return undefined
  const line = /^description:[ \t]*(.+)$/m.exec(frontmatter[1])
  if (line === null) return undefined
  const raw = line[1].trim()
  if (raw.startsWith('"') && raw.endsWith('"') && raw.length > 1) {
    return raw.slice(1, -1).replace(/\\"/g, '"').replace(/\\\\/g, '\\')
  }
  if (raw.startsWith("'") && raw.endsWith("'") && raw.length > 1) return raw.slice(1, -1).replace(/''/g, "'")
  return raw
}

const SKILL_INVOCATION = Object.freeze({ modelInvocable: false, userInvocable: true })
const RESOURCE_BASE = Object.freeze({ kind: 'directory', path: SKILLS_DIR })

/** Load one packaged skill, or `undefined` when it cannot be read. */
async function loadSkill(name, signal) {
  const url = new URL(`${name}/SKILL.md`, new URL('./skills/', import.meta.url))
  try {
    const content = await readFile(url, { encoding: 'utf8', signal })
    const description = readDescription(content)
    if (description === undefined) return undefined
    return { description, content, url }
  } catch (error) {
    if (error?.name === 'AbortError') throw error
    return undefined
  }
}

const skillsProvider = {
  name: PROVIDER_NAME,
  async list(options = {}) {
    const found = []
    for (const name of SKILL_NAMES) {
      const skill = await loadSkill(name, options.signal)
      if (skill === undefined) continue
      found.push({
        name,
        description: skill.description,
        invocation: SKILL_INVOCATION,
        provider: PROVIDER_NAME,
        source: 'bundled',
        resourceBase: RESOURCE_BASE,
        rank: BUNDLED_SKILL_RANK,
        locator: name,
      })
    }
    return found
  },
  async get(candidate, options = {}) {
    const name = typeof candidate.locator === 'string' ? candidate.locator : candidate.name
    const skill = await loadSkill(name, options.signal)
    if (skill === undefined) return undefined
    return {
      name,
      description: skill.description,
      invocation: SKILL_INVOCATION,
      provider: PROVIDER_NAME,
      source: 'bundled',
      resourceBase: RESOURCE_BASE,
      content: skill.content,
    }
  },
}

const BACKGROUND_OUTPUT = {
  type: 'object',
  additionalProperties: false,
  properties: {
    kind: { type: 'string', required: true, const: 'background' },
    action: { type: 'string', required: true },
    jobId: { type: 'string', required: true },
    logPath: { type: 'string' },
    configPath: { type: 'string' },
  },
}

const FOREGROUND_OUTPUT = {
  type: 'object',
  additionalProperties: false,
  properties: {
    kind: { type: 'string', required: true, const: 'foreground' },
    action: { type: 'string', required: true },
    ok: { type: 'boolean', required: true },
    exitCode: { required: true, oneOf: [{ type: 'integer' }, { type: 'null' }] },
    report: { type: 'string' },
    message: { type: 'string' },
    errorCode: { type: 'string' },
    remedy: { type: 'string' },
    logError: { type: 'string' },
    configPath: { type: 'string' },
    logPath: { type: 'string' },
    details: { type: 'json' },
  },
}

export const name = 'dsh-slopo'
export const inject = ['tools', 'skills']

/**
 * Register the skills, the settings namespace, and the tool.
 *
 * @param {import('@deepseek-ai/cordis').Context} ctx
 * @param {Record<string, unknown>} config validated composition config
 */
export function apply(ctx, config) {
  const logger = ctx.logger('dsh-slopo')
  const dshHome = dshHomeOf(ctx)

  // `config` is the live configuration, not a snapshot of the composition
  // layer: a settings write rewrites this entry's patch and the Loader
  // re-applies the plugin with the new values, so every read below sees the
  // deployment's current answer. There is deliberately no cached copy — a cache
  // is exactly what a reload invalidates.
  let writeSettings

  // The settings namespace IS this plugin's Config. The framework projects the
  // exported schema onto the Loader entry that composed it and addresses it by
  // that entry's id, which the bundle's patch declares as `dsh-slopo` — the
  // same string the browser card binds to. Nothing is registered here any more:
  // 0.1.7-rc.2 removed `ctx.settings.installSection`, because a section
  // assembled from a schema cannot disagree with the schema.
  //
  // `configure({ auto: false })` records that this entry ships its own page
  // (`client/client.js` registers one onto the Plugins page), so the deployment
  // must not also generate one for the same entry.
  ctx.inject(['settings'], (settingsCtx) => {
    try {
      settingsCtx.effect(
        () => settingsCtx.settings.configure({ auto: false }, ctx.fiber),
        'dsh-slopo: settings page policy',
      )
      writeSettings = (patch) => settingsCtx.settings.update(SETTINGS_NAMESPACE, patch)
    } catch (error) {
      logger.warn('dsh-slopo: settings namespace unavailable: %s', error?.message ?? error)
    }
  })

  ctx.skills.registerProvider(() => skillsProvider)

  /**
   * The slopo executable, installing it first when allowed.
   *
   * `installInto` is the directory the install runs in. It is deliberately NOT
   * the workspace: `uv tool install` has nothing to do with the project, and a
   * shell that must `cd` into a workspace that does not exist yet fails before
   * `uv` is ever reached.
   */
  async function ensureSlopo(settings, run, installInto) {
    const configured = typeof settings.binary === 'string' ? settings.binary.trim() : ''
    if (configured !== '' && existsSync(configured)) return configured
    const found = findSlopo(dshHome)
    if (found !== undefined) return found
    if (settings.autoInstall !== true) {
      return { error: 'SLOPO_NOT_INSTALLED', remedy: 'Set `autoInstall`, or install slopo yourself and set `binary`.' }
    }
    const install = await run(commandLine(['uv', ...uvInstallArgs()]), {
      env: installEnv(dshHome),
      timeoutMs: 900_000,
      workdir: installInto,
    })
    if (install.exitCode !== 0) {
      return {
        error: 'SLOPO_INSTALL_FAILED',
        remedy:
          'Install slopo manually with `uv tool install slopo --python 3.12`, or set the `binary` setting to ' +
          'an existing slopo executable.',
        detail: install.stderr || install.stdout,
      }
    }
    const installed = findSlopo(dshHome)
    if (installed === undefined) {
      return { error: 'SLOPO_INSTALL_MISSING', remedy: 'uv reported success but no executable appeared.' }
    }
    return installed
  }

  ctx.tools.register(
    defineTool({
      name: 'slopo',
      description:
        'Run slopo, an embedding-based duplicate-code detector, against the current workspace. ' +
        'Actions: "status" reports the resolved configuration and index state; "configure" updates the ' +
        'dsh-slopo settings; "prepare" runs the local index and then embeds (the slow, possibly costly ' +
        'step); "review" finds similar code involving Git changes; "analyze" triages the whole codebase; ' +
        '"analyze-one" reports a single cluster by hash; "update" upgrades the slopo CLI. Slopo is ' +
        'installed and driven as a separate process. "prepare" starts a background job by default, because ' +
        'indexing and embedding a repository takes minutes and slopo writes its progress to a log file rather ' +
        'than to stdout; everything else returns its report directly.',
      parameters: {
        action: {
          type: 'string',
          required: true,
          enum: ['status', 'configure', 'prepare', 'review', 'analyze', 'analyze-one', 'update'],
          description: 'What to do.',
        },
        base: { type: 'string', description: 'Git ref to compare against for "review". Defaults to HEAD.' },
        cluster: { type: 'string', description: 'Cluster hash for "analyze-one". Omit for the next cluster.' },
        run_in_background: {
          type: 'boolean',
          description:
            'Return a job id instead of the result, for a run long enough to watch. Defaults to true for ' +
            '"prepare" (the warm-up) and false for everything else, which is quick once the index is warm.',
        },
        config: {
          type: 'json',
          description:
            'Settings patch for "configure", using this plugin\'s own camelCase field names, for example ' +
            '{"embeddingModel":"ollama/nomic-embed-text:latest","embeddingDimensions":768}.',
        },
      },
      output: {
        schema: { oneOf: [BACKGROUND_OUTPUT, FOREGROUND_OUTPUT] },
        render: (_args, value) => {
          if (value.kind === 'background') {
            const log = value.logPath === undefined ? '' : ` Progress is written to ${value.logPath}.`
            return [
              {
                type: 'text',
                text:
                  `Started slopo ${value.action} as background job ${value.jobId}.${log} You will be notified when ` +
                  `it settles; collect it with job_output for "${value.jobId}" (add wait: true if you are blocked on it).`,
              },
            ]
          }
          const parts = []
          if (typeof value.report === 'string' && value.report !== '') parts.push(value.report)
          if (typeof value.message === 'string' && value.message !== '') parts.push(value.message)
          if (typeof value.logError === 'string' && value.logError !== '') parts.push(`Slopo log: ${value.logError}`)
          if (typeof value.remedy === 'string' && value.remedy !== '') parts.push(`Next: ${value.remedy}`)
          if (typeof value.logPath === 'string' && value.logPath !== '') parts.push(`(agent log: ${value.logPath})`)
          if (parts.length === 0) parts.push(`slopo ${value.action} finished with exit code ${value.exitCode}.`)
          return [{ type: 'text', text: parts.join('\n\n') }]
        },
      },
      async execute(args, exec) {
        const cwd = exec.agent?.session.header.cwd ?? process.cwd()
        const settings = config
        const paths = workspacePaths(dshHome, cwd, settings)
        const shell = ctx.get('shell')
        // Resolved once, up front, so `status` can probe without a second
        // resolution. The NO_SANDBOX_POLICY refusal stays with the actions that
        // actually execute something.
        const sandboxDefault = shell?.sandboxMode
        const policyService = sandboxDefault === undefined ? undefined : ctx.get('sandboxPolicy')
        const sandboxPolicy = policyService?.resolve(
          exec.agent === undefined ? {} : { session: exec.agent.session },
        )

        // Every return funnels through here. The harness enforces the declared
        // output schema against this value BEFORE materialising it, and an
        // explicit `undefined` property is not lossless JSON — which is exactly
        // how a probe result carrying `error: undefined` broke the status call.
        const foreground = (value) =>
          toJsonValue({
            kind: 'foreground',
            action: args.action,
            configPath: paths.configPath,
            logPath: paths.logFile,
            ...value,
          })

        if (args.action === 'status') {
          const binary = findSlopo(dshHome)
          const problems = []
          const slopoConfig = toSlopoConfig(settings, paths, problems)
          const missing = missingRequired(slopoConfig)

          // Two pre-flight checks, because slopo reports a bad embedding
          // configuration as the two words "Embedding failed." on stdout with
          // the real reason buried in its agent log. That is a slow way to
          // discover a wrong provider prefix or a dimension mismatch.
          let slopoVersion
          if (binary !== undefined && shell !== undefined) {
            try {
              const versionResult = await runShell(shell, {
                command: commandLine([binary, '--version']),
                workdir: paths.cwd,
                timeoutMs: 30_000,
                ...(sandboxPolicy === undefined ? {} : { sandboxPolicy }),
              })
              slopoVersion =
                versionResult.exitCode === 0
                  ? versionResult.stdout.text.trim().split('\n')[0]
                  : `exit code ${versionResult.exitCode}: ${versionResult.stderr.text.trim().slice(0, 200)}`
            } catch (error) {
              slopoVersion = `could not run: ${error?.message ?? error}`
            }
          }

          // A direct fetch rather than the shell seam: the probe is one small
          // HTTP request and does not belong behind a sandbox boundary that
          // exists to confine filesystem writes.
          const endpoint =
            missing.length === 0
              ? await probeEmbeddingEndpoint({
                  apiBase: typeof settings.embeddingApiBase === 'string' ? settings.embeddingApiBase : '',
                  model: String(slopoConfig.embedding_model ?? ''),
                  dimensions: Number(slopoConfig.embedding_dimensions ?? 0),
                  apiKey: typeof settings.embeddingApiKey === 'string' ? settings.embeddingApiKey : '',
                })
              : { checked: false, skipped: 'nothing is configured yet' }

          let message
          if (missing.length > 0) {
            message =
              `Not configured yet. Missing: ${missing.join(', ')}. Run this tool with action "configure" ` +
              'to set embeddingModel and embeddingDimensions, then "prepare".'
          } else if (endpoint.ok === false) {
            message =
              `Configured, but the embedding backend failed its check: ${endpoint.error}. ` +
              `(probed ${endpoint.url} with model "${endpoint.sentModel}")`
          } else if (endpoint.checked === true) {
            message =
              `Ready. ${binary ?? 'slopo'} will use "${slopoConfig.embedding_model}" at ` +
              `${Number(slopoConfig.embedding_dimensions)} dimensions, confirmed against ${endpoint.url}.`
          } else {
            message =
              `Configured against "${slopoConfig.embedding_model}" at ` +
              `${Number(slopoConfig.embedding_dimensions)} dimensions. Nothing was probed: ${endpoint.skipped}.`
          }

          return foreground({
            ok: missing.length === 0 && endpoint.ok !== false,
            exitCode: null,
            details: {
              dshHome,
              cwd,
              stateDir: paths.stateDir,
              configPath: paths.configPath,
              database: existsSync(paths.dbFile) ? paths.dbFile : null,
              ignoreFile: existsSync(paths.ignoreFile) ? paths.ignoreFile : null,
              agentLog: existsSync(paths.logFile) ? paths.logFile : null,
              slopoBinary: binary ?? null,
              slopoVersion: slopoVersion ?? null,
              slopoInstalledInto: binary === undefined ? null : dshHome,
              settingsNamespace: writeSettings === undefined ? null : SETTINGS_NAMESPACE,
              embeddingModel: slopoConfig.embedding_model ?? null,
              embeddingDimensions: slopoConfig.embedding_dimensions ?? null,
              apiKeyConfigured: typeof settings.embeddingApiKey === 'string' && settings.embeddingApiKey !== '',
              embeddingEndpoint: endpoint,
              // What slopo will actually look at, and the limit on how much of
              // it may be embedded without being asked. Both are the levers a
              // runaway scope is fixed with, so status has to name them.
              sourceDirExclude: effectiveExcludes(settings),
              useDefaultExcludes: settings.useDefaultExcludes !== false,
              maxIndexUnits: Number(settings.maxIndexUnits),
              missingSettings: missing,
              problems,
            },
            message,
          })
        }

        if (args.action === 'configure') {
          const patch = args.config
          if (patch === undefined || patch === null || typeof patch !== 'object' || Array.isArray(patch)) {
            return foreground({ ok: false, exitCode: null, message: 'The `config` parameter must be an object.', errorCode: 'BAD_PATCH' })
          }
          const unknown = Object.keys(patch).filter((key) => !SETTING_KEYS.includes(key))
          if (unknown.length > 0) {
            return foreground({
              ok: false,
              exitCode: null,
              errorCode: 'UNKNOWN_SETTING',
              message: `Unknown setting(s): ${unknown.join(', ')}.`,
              remedy: `Known settings: ${SETTING_KEYS.join(', ')}.`,
            })
          }
          if (writeSettings === undefined) {
            return foreground({
              ok: false,
              exitCode: null,
              errorCode: 'NO_SETTINGS_PROVIDER',
              message: 'No settings provider is mounted, so configuration cannot be persisted at runtime.',
              remedy: `Set these values in the dsh-slopo row of your cordis layer instead: ${JSON.stringify(patch)}`,
            })
          }
          await writeSettings(patch)
          return foreground({ ok: true, exitCode: 0, message: `Updated ${Object.keys(patch).join(', ')}.` })
        }

        if (shell === undefined) {
          return foreground({
            ok: false,
            exitCode: null,
            errorCode: 'NO_SHELL',
            message: 'No shell executor is available, so slopo cannot be run.',
            remedy: 'Load @deepseek-ai/dsh-bash-local (or another shell provider) into this profile.',
          })
        }

        // Resolve the CALLING SESSION's sandbox policy, the way the bash tool
        // does. `dsh-bash-sandbox.resolve()` stamps
        // `request.sandboxPolicy ?? ctx.sandboxPolicy.resolve()`, so omitting it
        // does not mean "unconfined" — it silently substitutes the DEPLOYMENT
        // default (`DSH_PERMISSION_MODE ?? 'workspace-write'`) for the session's
        // preset. That confines a call the session asked to run unconfined, and
        // on a host with no sandbox runner it fails with SandboxUnavailableError
        // before slopo is ever reached.
        if (sandboxDefault !== undefined && policyService === undefined) {
          return foreground({
            ok: false,
            exitCode: null,
            errorCode: 'NO_SANDBOX_POLICY',
            message: 'The mounted shell executor confines commands, but ctx.sandboxPolicy is absent.',
            remedy: 'Compose @deepseek-ai/dsh-sandbox-policy, or mount an unconfining shell executor.',
          })
        }

        // Slopo's state is deliberately outside the workspace, which a
        // workspace-write sandbox forbids writing to. Say so before a run and
        // name both ways out, rather than letting a write fail mid-embed.
        if (
          sandboxPolicy !== undefined &&
          sandboxPolicy.mode !== 'danger-full-access' &&
          !isInside(sandboxPolicy.workspaceRoot, paths.stateDir)
        ) {
          return foreground({
            ok: false,
            exitCode: null,
            errorCode: 'STATE_OUTSIDE_SANDBOX',
            message:
              `This session runs under the "${sandboxPolicy.mode}" sandbox, which permits writes only under ` +
              `${sandboxPolicy.workspaceRoot} — but slopo's index, config and log live in ${paths.stateDir}.`,
            remedy:
              'Either run this session under the danger-full-access preset, or set `stateDir` to a directory ' +
              'inside the workspace using action "configure".',
          })
        }

        /**
         * Run one command through the shell seam.
         *
         * `runShell` returns the seam's own result; everything below wants the
         * flattened strings, so the adaptation happens once, here.
         *
         * `workdir` is overridable because installing slopo has nothing to do
         * with the workspace: the workspace may not even exist yet on a fresh
         * session, and a shell that cannot `cd` there fails before `uv` is
         * reached. The plugin's own state directory is always a real directory
         * by the time an install runs.
         */
        const run = async (command, { env, timeoutMs, signal, workdir } = {}) => {
          const result = await runShell(shell, {
            command,
            workdir: workdir ?? paths.cwd,
            timeoutMs: timeoutMs ?? (Number(settings.timeoutMs) || 600_000),
            ...(signal === undefined ? {} : { signal }),
            // Merges over a parent-derived base, so PATH and HOME survive.
            ...(env === undefined ? {} : { env }),
            // Omitting this substitutes the deployment default; see above.
            ...(sandboxPolicy === undefined ? {} : { sandboxPolicy }),
          })
          return {
            exitCode: result.exitCode,
            stdout: result.stdout.text,
            stderr: result.stderr.text,
            truncated: result.stdout.truncated || result.stderr.truncated,
            timedOut: Boolean(result.timedOut),
          }
        }

        if (args.action === 'update') {
          const result = await run(commandLine(['uv', ...uvInstallArgs({ upgrade: true })]), {
            env: installEnv(dshHome),
            timeoutMs: 900_000,
            signal: exec.signal,
          })
          return foreground({
            ok: result.exitCode === 0,
            exitCode: result.exitCode,
            report: result.stdout.trim(),
            errorCode: result.exitCode === 0 ? undefined : 'UPDATE_FAILED',
            remedy: result.exitCode === 0 ? undefined : result.stderr.trim(),
          })
        }

        // Everything below actually needs slopo.
        const problems = []
        const slopoConfig = toSlopoConfig(settings, paths, problems)
        const missing = missingRequired(slopoConfig)
        if (missing.length > 0) {
          return foreground({
            ok: false,
            exitCode: null,
            errorCode: 'NOT_CONFIGURED',
            message: `Slopo is not configured for this workspace yet. Missing: ${missing.join(', ')}.`,
            remedy:
              'Call this tool with action "configure" first, for example ' +
              '{"embeddingModel":"ollama/<model>:latest","embeddingDimensions":768,"embeddingApiBase":"http://127.0.0.1:11434"}.',
            details: { missing, problems },
          })
        }

        // The state directory and the config file come FIRST, before the
        // executable is resolved. The config is a pure function of the
        // settings — nothing about it needs slopo to exist — and writing it
        // early means a run that stops at "not installed" still leaves the
        // resolved configuration on disk to look at. It also gives the install
        // below a real working directory to run in.
        await mkdir(paths.stateDir, { recursive: true })
        await writeFile(paths.configPath, renderSlopoConfig(slopoConfig), 'utf8')

        const binary = await ensureSlopo(settings, run, paths.stateDir)
        if (typeof binary !== 'string') {
          return foreground({ ok: false, exitCode: null, errorCode: binary.error, message: binary.remedy, remedy: binary.detail })
        }

        const env =
          typeof settings.embeddingApiKey === 'string' && settings.embeddingApiKey !== ''
            ? { SLOPO_EMBEDDING_API_KEY: settings.embeddingApiKey }
            : undefined

        // Every action indexes FIRST, so the size gate sees the real scope
        // before any embedding is paid for. Slopo's own >1000 guard cannot do
        // this: it measures the pre-existing backlog, and a fresh database has
        // no units at all — which is exactly when a runaway costs the most.
        const excludes = effectiveExcludes(settings)
        const indexArgs = slopoArgs(paths.configPath, 'index')
        const restArgs =
          args.action === 'prepare'
            ? [slopoArgs(paths.configPath, 'embed')]
            : [slopoArgs(paths.configPath, args.action, { base: args.base, cluster: args.cluster })]

        /**
         * Index, check the budget, then run the action.
         * Returns a refusal instead of running when the scope is too large.
         */
        const runScoped = async (signal) => {
          const indexed = await run(commandLine([binary, ...indexArgs]), { env, signal })
          const parsed = parseIndexOutput(indexed.stdout)
          // Prefer the database. `Indexed N` counts only what was NEWLY indexed,
          // so it reads zero on a warm database whose backlog is still full —
          // exactly the state a refused run leaves behind.
          const fromDb = readIndexCounts(paths.dbFile)
          const counted =
            fromDb === undefined
              ? parsed
              : { units: fromDb.unembedded, files: fromDb.files, inScope: fromDb.units, embedded: fromDb.embedded }
          if (indexed.exitCode !== 0) return { refused: undefined, counted, outcome: indexed }
          const decision = checkBudget(counted, Number(settings.maxIndexUnits), excludes)
          if (!decision.allowed) return { refused: decision.reason, counted, outcome: undefined }
          const restCommand = restArgs.map((argv) => commandLine([binary, ...argv])).join(' && ')
          return { refused: undefined, counted, outcome: await run(restCommand, { env, signal }) }
        }

        const scopeRefusal = (reason, counted) =>
          foreground({
            ok: false,
            exitCode: null,
            errorCode: 'SCOPE_TOO_LARGE',
            message: reason,
            remedy: budgetRemedy(Number(settings.maxIndexUnits), excludes),
            details: { counted, excludes, maxIndexUnits: Number(settings.maxIndexUnits) },
          })

        // Background is for the long warm-up, not for every action. A completion
        // notice is best-effort: a KILLED job deliberately produces none, and an
        // agent whose turn has ended may have the message injected rather than be
        // woken for it. A review that returns its report directly is worth more
        // than a job id the caller has to remember to collect.
        const wantsBackground = args.run_in_background ?? BACKGROUND_BY_DEFAULT.has(args.action)
        const jobs = ctx.get('jobs')

        if (wantsBackground && jobs !== undefined) {
          const jobId = jobs.start({
            kind: 'slopo',
            label: `slopo ${args.action}`,
            // Ownership is fenced by SESSION ID, not by the agent object: the
            // registry cancels and awaits the job when that session's agent is
            // disposed, and it looks the id up itself. Passing `exec.agent`
            // here registered a job no session could collect or stop.
            ...(exec.agent === undefined ? {} : { owner: exec.agent.id }),
            run: () => {
              const controller = new AbortController()
              // `done` resolves to a JobOutcome: `{ status, detail, result }`.
              // The report rides `result`, which the registry hands to the
              // model on its first read after settlement — read it back with
              // job_output. (The field is `result`, not `output`: the ring
              // carries a job's stream, and `result` carries the return value
              // of one whose product is a value rather than a stream.)
              const done = (async () => {
                const { refused, counted, outcome } = await runScoped(controller.signal)
                const logDetail = await readLogTail(paths.logFile)
                if (refused !== undefined) {
                  return {
                    status: 'failed',
                    detail: 'SCOPE_TOO_LARGE',
                    result: `${refused}\n\n${budgetRemedy(Number(settings.maxIndexUnits), excludes)}`,
                  }
                }
                if (outcome.exitCode === 0) {
                  return { status: 'completed', detail: 'exit code: 0', result: outcome.stdout.trim() || 'No duplicates found' }
                }
                const explained = explainFailure({ stderr: outcome.stderr, stdout: outcome.stdout, logDetail })
                return {
                  status: 'failed',
                  detail: explained.code,
                  result: [explained.message, explained.remedy, logDetail.trim()].filter((line) => line !== '').join('\n\n'),
                }
              })()
              return { cancel: () => controller.abort(), done }
            },
          })
          return toJsonValue({ kind: 'background', action: args.action, jobId, logPath: paths.logFile, configPath: paths.configPath })
        }

        const { refused, counted, outcome } = await runScoped(exec.signal)
        const logDetail = await readLogTail(paths.logFile)
        if (refused !== undefined) return scopeRefusal(refused, counted)
        if (outcome.exitCode === 0) {
          return foreground({ ok: true, exitCode: 0, report: outcome.stdout.trim() || 'No duplicates found' })
        }
        const explained = explainFailure({ stderr: outcome.stderr, stdout: outcome.stdout, logDetail })
        return foreground({
          ok: false,
          exitCode: outcome.exitCode,
          errorCode: explained.code,
          message: explained.message,
          remedy: explained.remedy,
          logError: lastLogError(logDetail),
        })
      },
    }),
  )
}

/** Read the tail of slopo's agent log, tolerating a missing file. */
async function readLogTail(path) {
  try {
    const contents = await readFile(path, 'utf8')
    return contents.length > 16_000 ? contents.slice(-16_000) : contents
  } catch {
    return ''
  }
}

/** True when `path` is `root` itself or sits underneath it. */
function isInside(root, path) {
  const prefix = root.endsWith(sep) ? root : root + sep
  return path === root || path.startsWith(prefix)
}