agent-session-resume is a reusable skill for continuing work from a prior AI coding-agent session without losing context, duplicating completed work, or overwriting unrelated changes.

It is designed for handoffs between tools such as Claude Code, Codex, Cursor, Antigravity, and OpenCode.

Instead of asking the next agent to guess what happened, the skill makes it produce a handoff checkpoint first: the prior goal, what is already done, what is still open, and the next action to take before editing.

The skill gives an agent a disciplined resume workflow:

• locate the most relevant prior transcript, export, artifact, or session summary
• read the full available context before taking action
• reconstruct the original goal, completed work, decisions, and stopping point
• extract explicit and implicit tasks
• classify each task as DONE, PARTIALLY DONE, or NOT DONE
• continue from the first unfinished step without repeating completed work

.claude-plugin/
  marketplace.json
  plugin.json
skills/
  agent-session-resume/
    SKILL.md
    agents/
      openai.yaml
    references/
      antigravity.md
      claude-code.md
      codex.md
      cursor.md
      opencode.md

The quickest way to install is the skills CLI (npx skills). It reads the canonical skills/agent-session-resume folder from this repo and installs it for whichever agent you target — no manual cloning or copying.

Install (interactive — choose which agents to install into):

npx skills add hacktivist123/agent-session-resume

Install for specific agents without prompts:

npx skills add hacktivist123/agent-session-resume -a claude-code -a codex -a cursor -a opencode -y

Install globally (user-level instead of the current project) with -g:

npx skills add hacktivist123/agent-session-resume -g

Update to the latest version:

npx skills update agent-session-resume

npx skills update with no name updates every installed skill. List or remove the skill with npx skills list and npx skills remove agent-session-resume.

After installing or updating, restart the agent (or start a new session) so it loads the current instructions.

If you prefer a Claude Code plugin with a namespaced command instead of the npx skills flow, add the marketplace and install the plugin:

/plugin marketplace add hacktivist123/agent-session-resume
/plugin install agent-session-resume@hacktivist123
/reload-plugins

CLI equivalent:

claude plugin marketplace add hacktivist123/agent-session-resume
claude plugin install agent-session-resume@hacktivist123

This gives the namespaced command /agent-session-resume:agent-session-resume. The marketplace id is hacktivist123 (defined in .claude-plugin/marketplace.json), so the install reference is agent-session-resume@hacktivist123. Restart Claude Code or run /reload-plugins after installing.

npx skills supports 70+ agents; pass -a <agent> to target one (for example -a github-copilot, -a windsurf, or -a cline). For an agent the CLI does not cover, load skills/agent-session-resume/SKILL.md as the main instruction document and use the relevant platform file from skills/agent-session-resume/references/.

Short prompts should be enough; the skill carries the platform-specific discovery rules.

For more examples, see the cookbook.

For benchmark areas, fixture expectations, and issue/PR evaluation fields, see Benchmarking.

Continue the most recent Codex session for the current repository:

/agent-session-resume:agent-session-resume

Continue the most recent Codex session for this repository.

Continue from a specific handoff file:

/agent-session-resume:agent-session-resume

Continue from ./handoff.md.

Expected first response shape:

Brief context summary
Loaded skill: path=<loaded SKILL.md path or unknown>; source/version=<marker or unknown>
Task status breakdown
User deferrals
Clear next action

After that checkpoint, the agent should continue from the first unfinished step without redoing completed work.

Resume reports should identify the loaded skill path and source/version marker when available, and should say unknown when the runtime does not expose them. Useful markers include the Claude plugin manifest version, marketplace package version, git commit, tag, package source, or a checksum of the loaded SKILL.md.

When comparing Codex and Claude Code behavior, compare the known install paths before concluding that the same skill version ran:

${CODEX_HOME:-$HOME/.codex}/skills/agent-session-resume/SKILL.md
$HOME/.claude/skills/agent-session-resume/SKILL.md

Explicit user deferrals such as "skip", "park", "leave out", or "not now" should be preserved in resume context. A vague prompt such as "Proceed" should not unpark that scope without confirmation.

Recommended plugin install gives the namespaced command:

/agent-session-resume:agent-session-resume

Alternative standalone install gives the shorter skill command:

/agent-session-resume

If the plugin command does not appear after installation, run /reload-plugins and check the marketplace/plugin manifests with:

claude plugin validate .
claude plugin validate .claude-plugin/plugin.json
claude plugin validate .claude-plugin/marketplace.json

Run the package and fixture validators:

python3 scripts/validate-skill-package.py
python3 scripts/validate-fixtures.py
python3 scripts/validate-trigger-matrix.py
claude plugin validate .
claude plugin validate .claude-plugin/plugin.json
claude plugin validate .claude-plugin/marketplace.json

The standalone skill under skills/agent-session-resume is the source of truth. The optional Claude plugin wrapper uses the repo root as its source, so it shares that canonical skill folder instead of maintaining a second copy. The fixtures in tests/fixtures/ cover Claude Code, Codex, Cursor, Antigravity, and OpenCode handoff shapes. Each scenario pairs sample session material with the expected context summary, task status breakdown, and next action. tests/trigger-matrix.json tracks prompt coverage for manual or automated trigger testing.

Use docs/Benchmarking.md when proposing improvements so PRs explain what behavior changed, how it was measured, and what a good result looks like.

MIT