thrift-copilot

/thrift-copilot

Bootstraps cost-conscious patterns in a Copilot-CLI project. Reads .thrift.json (or seeds it), patches .github/hooks/thrift-*.json with hook registrations, mirrors summariser + audit state into Copilot's store_memory (file-fallback if MCP unreachable), and surfaces end-of-session audit via Copilot's agentStop hook.

Usage

/thrift-copilot                       # one-time setup; idempotent
/thrift-copilot summarise             # manual summariser trigger
/thrift-copilot audit                 # write audit report now
/thrift-copilot --force               # re-seed .thrift.json
/thrift-copilot --no-instrument       # skip hook installation
/thrift-copilot --dry-run             # preview without writing

Flags

• --force — overwrite existing .thrift.json.
• --no-instrument — skip the .github/hooks/*.json patch (just seed config).
• --dry-run — print what would be patched; don't write.
• --no-store-memory — disable Copilot store_memory mirroring; use file-only state. Useful for sandbox/offline runs.

Pipeline

Phase	File	Purpose
0	phases/0-preflight.md	detect context-mode-copilot + Copilot version + store_memory availability
1	phases/1-config.md	seed/load .thrift.json + compute thresholds
2	phases/2-instrument.md	patch .github/hooks/thrift-*.json (append-only)
3	phases/3-summariser.md	summarise current window; mirror to store_memory
4	phases/4-cache-prime.md	disabled by default — Copilot intermediates the model layer; document opt-in
5	phases/5-audit.md	write audit report + mirror to store_memory

Rules

1. Append-only hook patches. Never modify or remove existing entries in .github/hooks/*.json. Use thrift- command-path sentinel for safe revert via unpatchHooks.
2. Cache prime is disabled by default and warns on opt-in. Copilot sits between the user and the underlying model, so direct prime calls are not observably effective. Enable only if a future Copilot release exposes cache-hit telemetry.
3. Summariser is advisory. Writes summary to file + mirrors to store_memory(scope: "repository", key: "thrift/summary/<ts>") + notifies via stderr (Copilot surfaces stderr in the TUI). No /compact equivalent exists in Copilot — advisory is "consider starting a fresh session or running gh copilot reset".
4. Audit always runs on agentStop. Phase 5 reads from .thrift-state.json (and from store_memory if file is wiped).
5. store_memory is best-effort. If the MCP tool is unreachable or the request fails, the bridge falls back to file-only mode silently and records a storeMemoryDegraded: true flag in state.

Lib modules

• lib/config-loader.mjs — loadConfig(path) → {ok, config | errors, warning?}. Independent copy with a Copilot-flavoured storeMemory section in DEFAULTS.
• lib/cost-estimator.mjs — estimate({tokensInUncached, tokensInCached, tokensOut, model}) → {actualUSD, baselineUSD, savedRatio, breakdown}. OpenAI rate table (gpt-5, gpt-5-nano, etc.). All rates marked assumed; verify against current OpenAI pricing.
• lib/settings-patcher.mjs — patchHooks({hooksDir, hooksToAdd, dryRun}) / unpatchHooks({hooksDir, sentinel}). Writes one JSON file per event under .github/hooks/. Append-only.
• lib/store-memory-bridge.mjs — storeMemoryWrite({key, value, scope, invoker}) and storeMemoryRead({key, scope, invoker}) with a file fallback at .thrift/store-memory-fallback/<key>.json. Invoker is the host-supplied wrapper around Copilot's store_memory MCP tool; pass a mock in tests.

On error

• .thrift.json invalid → abort with field-level errors (Phase 1).
• Existing hook conflict (same command already registered) → skip that specific entry; continue with the others.
• Cache prime never runs unless cache.enabled = true AND cache.intermediationWarning = false (force opt-in).
• Summariser model call fails → log to .thrift-state.json; user can retry via /thrift-copilot summarise.
• store_memory invoker throws → fall back to file at .thrift/store-memory-fallback/<key>.json; record degradation.

When done (Phase 5)

Print:

Thrift audit: <duration> min session, <turns> turns,
  $<actual> actual vs $<baseline> baseline (saved <%>).
  Report: <output-path>
  Memory mirror: <ok|degraded>

References

• references/porting-notes.md — Copilot-vs-CC primitive differences, known unknowns, future spike list.
• docs/superpowers/specs/2026-05-18-harness-thrift-per-platform-decomposition.md — decomposition spec (Copilot section ~1.5w).
• plugins/harness-thrift/skills/thrift/SKILL.md — Claude Code source-of-truth.