fix(harness): hide host offload path from sandbox agents

[jaideeppyne]

Summary

• keep compaction offloading enabled for sandbox-backed filesystems
• omit the host-side session archive path from the agent-facing summary because that path is not resolvable inside the sandbox
• preserve the existing archive-path guidance for local filesystems
• add regression coverage for both sandbox and local behavior

Fixes #2566.

Validation

• mvn -pl agentscope-harness -am -Dtest=MemoryFlushManagerOffloadTest -Dsurefire.failIfNoSpecifiedTests=false test — 5 tests run, 0 failures, 0 errors, 0 skipped; reactor build succeeded
• mvn -q -pl agentscope-harness spotless:check — passed
• git diff --check — passed

Impact evidence

MemoryFlushManager.resolveOffloadPath currently resolves the archive through the host-side WorkspaceManager path, while sandbox filesystem operations use a separate namespace. Returning an empty path activates the compactor’s existing path-less summary branch, so the archive is still persisted but the agent is no longer told it can read a host-only path.

Risk and rollback

The behavior change is limited to AbstractSandboxFilesystem implementations. Local filesystem summaries retain their current archive reference. Reverting this commit restores the previous behavior; no persisted data format or public API changes.

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[jaideeppyne]

Rebase complete (conflict resolved)

Rebased onto latest main after upstream refactored resolveOffloadPath to delegate to SessionTranscriptWriter#resolveContextPath.

Resolution

• Keep sandbox guard: if filesystem is AbstractSandboxFilesystem, return "" (do not advertise host path).
• Otherwise delegate to SessionTranscriptWriter (matches current main).
• Local-path test now expects the workspace-relative path returned by SessionTranscriptWriter (agents/agent-a/sessions/session-1.jsonl).

Evidence

• mvn -pl agentscope-harness -am -Dtest=MemoryFlushManagerOffloadTest -Dsurefire.failIfNoSpecifiedTests=false test → 5 tests, 0 failures
• mvn -q -pl agentscope-harness spotless:check → passed

[jaideeppyne]

Conflict resolution status

Conflict with main is real: resolveOffloadPath was refactored on main to delegate to SessionTranscriptWriter#resolveContextPath.

A rebased fix is ready locally and validated:

mvn -pl agentscope-harness -am -Dtest=MemoryFlushManagerOffloadTest \
  -Dsurefire.failIfNoSpecifiedTests=false test
# Tests run: 5, Failures: 0
mvn -q -pl agentscope-harness spotless:check  # passed

Resolution shape (on top of current main):

public String resolveOffloadPath(RuntimeContext rc, String agentId, String sessionId) {
    if (workspaceManager.getFilesystem() instanceof AbstractSandboxFilesystem) {
        return "";
    }
    return new SessionTranscriptWriter(workspaceManager)
            .resolveContextPath(rc, agentId, sessionId);
}

Local-path test expects workspace-relative path agents/agent-a/sessions/session-1.jsonl.

Push blocked: OAuth token lacks workflow scope, and rebasing onto main updates .github/workflows/*, which GitHub rejects without that scope. Branch tip remains the last green commit until a token with workflow can force-push the rebase (or conflict is resolved in the GitHub UI).

[jaideeppyne]

Rebased and force-pushed

Conflict with main resolved and branch updated.

Resolution

• Sandbox filesystems: resolveOffloadPath returns "" (do not advertise host path)
• Local filesystems: delegate to SessionTranscriptWriter#resolveContextPath (workspace-relative path)

Local validation

• mvn -pl agentscope-harness -am -Dtest=MemoryFlushManagerOffloadTest -Dsurefire.failIfNoSpecifiedTests=false test → 5 tests, 0 failures
• mvn -q -pl agentscope-harness spotless:check → passed