# 2026-05-28

## Broker dead-code cleanup — session cache removed, issuer-machinery claim corrected

Started the follow-up cleanup slice the 2026-05-27 journal flagged under "Still dormant (follow-up cleanup)." Before deleting anything, mapped the full reference graph for every candidate. The mapping surfaced a material error in yesterday's dormant list.

### Correction to the 2026-05-27 "dormant" list

Yesterday's entry said of the issuer/issuance/`/tokens`/Sweeper machinery: "All of this is now unreachable from the live code paths." That is **wrong** for most of it. Verified live references:

- `Issuer.List` ← `GET /tokens` (server.go:464, route at server.go:265)
- `Issuer.Revoke` ← `DELETE /tokens/{label}` (server.go:484, route 266)
- `Issuer.RotateLabel` ← `POST /tokens/{label}/rotate` (server.go:511, route 267)
- `mintForWorld` / `appendIssuance` ← reachable via `RotateLabel`
- `readIssuances` / `revokeIssuance` / `lookupWorld` ← reachable via the three routes AND the Sweeper (`main.go:189` → `sweeper.go:155,212`)

So the per-user issuance subsystem is registered, reachable, and user-facing. What is actually true: nothing **populates** the issuances Secret anymore — the only writer was `Issuer.Mint`, which now has zero callers — so the `/tokens` API operates on a permanently-empty dataset. Vestigial, not dead. Retiring it is a product decision (removing a live HTTP surface + a Sweeper refactor to drop its `*Issuer` dependency), not a dead-code sweep. Left for an explicit go/no-go.

### What WAS genuinely dead, and got removed

`sessionCache` / `mcp_session.go`. The open-reads + per-world-write-token rework left it constructed-but-never-read: the only production reference was `newSessionCache(...)` assigned to the `mcpGateway.sessionCache` field at `mcp_gateway.go:74`, and nothing ever dereferenced the field. Dispatch goes through `worldWriteTokens.Provision`, never `GetOrMint`/`Invalidate`.

Removed:
- `mcp_session.go` (whole file: `sessionCache`, `session`, `cachedWorldToken`, `mintFunc`, `mintOutcome`, `errInvalidEmail`, LRU/idle eviction, singleflight).
- `mcp_session_test.go` (whole file).
- `mcpGateway.sessionCache` field + the `newSessionCache(...)` wiring in `newMCPGateway`.
- `golang.org/x/sync` dependency (singleflight was its only consumer) — dropped by `go mod tidy` from `tools/go.mod` + `go.sum`.

`canonicalEmail` is NOT in this file (it lives in `mcp_auth.go`, used by live write paths) — left untouched. Fixed three stale comments that described the old singleflight+sessionCache token-reuse behavior (one in `mcp_tools_write.go` handleMarkAppend doc, two in `mcp_tools_write_test.go`'s merge-dispatch test) to describe the per-world write-token reuse that actually happens now.

### Still orphaned by this change (noted, not yet removed)

`cfg.Server.MCP.SessionMaxIdle` + `MaxSessions` (config.go) — validated and defaulted but no longer consumed by any code after the session cache is gone. They no-op now. Folding them into the larger `/tokens`-retirement decision rather than touching the chart/config surface in this minimal diff. `FirstMint*` knobs stay live (the write dispatch retry loop still uses them).

### Verification

`go build ./...`, `go test -race ./...` (broker module), and `pre-commit.sh` (fmt + vet + lint across all four modules) all green. Pure dead-code removal — no behavior change on any live path.