agent-session-resume

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, 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.

What It Does

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

Repository Layout

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

Install

This repo is distributed primarily as a skill. The canonical installable package is:

skills/agent-session-resume

Codex

Ask Codex to install it:

Install the skill from hacktivist123/agent-session-resume at skills/agent-session-resume

Manual install:

tmp_dir="$(mktemp -d)"
git clone --depth 1 https://github.com/hacktivist123/agent-session-resume "$tmp_dir/agent-session-resume"
mkdir -p "${CODEX_HOME:-$HOME/.codex}/skills"
cp -R "$tmp_dir/agent-session-resume/skills/agent-session-resume" "${CODEX_HOME:-$HOME/.codex}/skills/"

Restart Codex after installing.

Claude Code

Recommended plugin install:

/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

After CLI install, restart Claude Code or run /reload-plugins in Claude Code.

This installs the skill as a Claude Code plugin command:

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

The plugin points at the same canonical skills/agent-session-resume folder used by the standalone skill package.

Alternative standalone skill install:

Install the standalone Claude Code skill from https://github.com/hacktivist123/agent-session-resume.
Copy the repository folder skills/agent-session-resume into ~/.claude/skills/agent-session-resume.
Do not use the Claude Code plugin marketplace for this standalone flow.

Manual standalone install:

tmp_dir="$(mktemp -d)"
git clone --depth 1 https://github.com/hacktivist123/agent-session-resume "$tmp_dir/agent-session-resume"
mkdir -p "$HOME/.claude/skills"
cp -R "$tmp_dir/agent-session-resume/skills/agent-session-resume" "$HOME/.claude/skills/"

Restart Claude Code after installing.

Use the standalone install if you prefer the shorter /agent-session-resume command or do not want to use Claude Code plugins.

Choose one Claude Code install path. Installing both the plugin and standalone skill can show duplicate short command suggestions; the namespaced plugin command avoids ambiguity.

Other Agents

For agents that do not support skill folders directly, load skills/agent-session-resume/SKILL.md as the main instruction document and use the relevant platform file from skills/agent-session-resume/references/.

Usage

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

For more examples, see the cookbook.

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
Task status breakdown
Clear next action

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

Claude Code Notes

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

Checks

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, 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.

License

MIT