feat(agent): add DeepSeek Harness runtime

[BobbyZhouZijian]

Motivation

CORAL supports several coding-agent CLIs but cannot currently run DeepSeek's official Harness. This adds first-class support for the official dsh --profile headless surface while preserving CORAL's runtime, model, gateway, sandbox, and shared-state contracts.

Changes

• Add a dsh runtime with deepseek, deepseek-harness, and deepseek_harness aliases.
• Run the official headless profile with .dsh shared state, AGENTS.md instructions, subprocess logging, sandbox and OS-user isolation support.
• Map CORAL gateway credentials to DEEPSEEK_BASE_URL and DEEPSEEK_API_KEY.
• Generate a final Cordis overlay so agents.model and the optional provider override the DSH profile defaults.
• Cover registry lookup, argv construction, model overlays, environment mapping, runtime options, and the current no-resume limitation.
• Document DSH across the English and Chinese READMEs, runtime/setup/config/gateway guides, and keep the README agent tables aligned (including existing Pi support).

DeepSeek Harness's current headless profile does not expose a session id or resume argument. CORAL restarts therefore create a fresh DSH session with a continuation prompt; existing configurations need no migration, and the compatibility aliases remain accepted.

Test plan

• uv run ruff check . — passed
• uv run ruff format --check . — passed (137 files already formatted)
• uv run pytest tests/ -q — 694 passed, 1 skipped
• cd docs && npm run build — passed; 41 static pages generated
• git diff --check — passed

The first full pytest run exposed stale local editable-install version metadata. Reinstalling the checkout into .venv corrected the environment; the subsequent full run passed as reported above.

Affected areas

• coral/agent/ (runtime, manager, heartbeat, warmstart)
• coral/grader/ (daemon, TaskGrader, subprocess grader, loader)
• coral/hub/ (attempts, notes, skills, checkpoint)
• coral/workspace/ (project setup, worktrees, grader env)
• coral/cli/ (commands, helpers)
• coral/hooks/ (post_commit / submit_eval)
• coral/template/ (CORAL.md, bundled skills/agents)
• coral/gateway/ (LiteLLM gateway)
• coral/web/ (dashboard)
• examples/ (new or modified task)
• docs/ (docs site)
• CI / tooling / packaging
• Other: root English and Chinese READMEs

Checklist

• PR targets the dev branch (not main).
• Title follows Conventional Commits (feat:, fix:, docs:, refactor:, ...).
• uv run pytest tests/ -v passes locally.
• uv run ruff check . and uv run ruff format --check . pass.
• Added or updated tests under tests/ for any behavior change.
• Updated docs (docs/content/, README, or relevant skill under .claude/skills/) for any user-visible or contract change.
• If this changes a config field, CLI flag, hook, or runtime contract — noted the migration path in the PR description.
• New examples/<task>/: coral validate <task> succeeds and a smoke run produces at least one finalized score. No hidden answer keys committed under seed/.
• AI-assisted PR: a human author has read every changed line and can defend the design. See AGENTS.md.

Authored with assistance from Codex. I read every changed line, ran the tests above locally, and verified the behavior described in the test plan.

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Project	Deployment	Actions	Updated (UTC)
coral-docs	Building	Preview	Aug 21, 2026 12:06pm
coral-web	Building	Preview	Aug 21, 2026 12:06pm

[BobbyZhouZijian]

Superseded by #248 after renaming the head branch to feat/dsh-runtime.