feat(amplifier): resume with full conversation history by default

[danshapiro]

What changed

Every Freshell-managed Amplifier resume now launches amplifier session resume --full-history <sessionId> instead of amplifier resume <sessionId>. The session resume subcommand form is required because plain amplifier resume rejects --full-history.

• extensions/amplifier/freshell.json — manifest resumeArgs
• server/coding-cli/providers/amplifier.ts — getResumeArgs
• crates/freshell-platform/src/cli_launch_goldens.rs — amplifier spec, goldens G-A2/G-A4b, manifest-parity golden
• crates/freshell-freshagent/src/terminal_tabs.rs — recording spec + argv assertion (+1 comment)
• JS tests — updated assertions in amplifier-provider.test.ts, amplifier-session-association.test.ts, amplifier-stub-adoption-contract.test.ts
• e2e fixtures — fake-amplifier-cli.mjs / fake-amplifier-activity-cli.mjs recognize the new argv shape (session id = last element)
• e2e specs — amplifier argv assertions updated in amplifier-restore-rust, remote-tab-linkage-rust, mcp-qa-smoke-rust, sidebar-click-resume, terminal-activity-rust (codex assertions untouched)
• Comment-only sweep of stale amplifier resume <id> wording: freshell-ws/src/terminal.rs, freshell-sessions/src/amplifier_stub.rs, freshell-server/src/existence_by_id.rs, freshell-terminal/src/registry.rs, freshell-ws/tests/amplifier_launcher_identity.rs

Why

Resumed Amplifier sessions previously showed Amplifier's truncated "…N earlier messages" tail. With --full-history, resumed sessions show the full conversation history.

How to verify

• Full coordinated JS suite (npm test): green — client 4793, server 4825, electron 350 passed. Two first-run flakes (monaco-mock render race, remote-proxy timeout race) passed in isolation and on rerun — pre-existing.
• cargo test --workspace: green — 100 suites, 0 failures.
• Opt-in real-CLI contract test passed against real amplifier v2026.08.01-0cad320 (FRESHELL_RUN_REAL_PROVIDER_CONTRACTS=1), directly exercising session resume --full-history.
• Affected e2e-browser specs (--project=rust-chromium): all amplifier argv assertions green. 4 tests fail, but a baseline run at origin/main @ 2d4fefb shows the IDENTICAL 4 failures at identical lines — pre-existing main debt, not this branch:
  1. amplifier-restore-rust ensure-after-GC expectation superseded by resume-validation AD-5 (PR Resume validation: disk-existence gate before resuming coding-CLI sessions #591)
  2. – 4. codex legs broken by FRESHELL_CODEX_MANAGED_LAUNCH default-ON vs plain fake CLI fixtures

Compatibility / breaking changes

No version guard added — requires an Amplifier CLI that supports session resume --full-history (verified on v2026.08.01). Older Amplifier builds would fail resume; deemed acceptable, but flagging for reviewers in case you disagree.

Suggested follow-ups (separate issues, not this PR)

• Reconcile amplifier-restore-rust.spec.ts with AD-5 resume-validation behavior
• Revisit the three codex specs vs the S5.e managed-launch default

Generated with Amplifier

Co-Authored-By: Amplifier [email protected]