{"answer":"I've reviewed the diff against the checked-out code. Findings:\n\n🔴 `bug` services/proxy/src/config.rs:83: `Duration::from_hours` (and `from_mins` at line 84, plus the test uses at 350-351) do not exist on stable `std::time::Duration` — they are unstable `duration_constructors` methods, and `rust-toolchain.toml` pins `channel = \"stable\"` with no feature gate. The proxy does not compile; the whole sweep feature is dead on arrival.\n\n🟠 `bug` services/proxy/src/metrics.rs:94: `values()` returns `sweep_bytes_reclaimed` before `sweep_blobs_removed`, but `COUNTERS` (lines 51-57) lists `sweep_blobs_removed_total` before `sweep_bytes_reclaimed_total`, and `render` zips them positionally. Each sweep counter is published under the other's name — `cairn_proxy_sweep_bytes_reclaimed_total`, the one docs/operations.md tells operators to alert on, actually carries the blob count. This is exactly the fifth-under-fourth's-name failure the adjacent comment (line 30-32) claims the pairing prevents.\n\n🟠 `bug` services/proxy/src/sweep.rs:232: `clear_partials` unlinks every file in `incoming` with no age check, but `BlobWriter` (store.rs:171-180, 242-259) keeps an open temp file there for the whole of a download — minutes for a 200 MiB artifact. A sweep concurrent with an in-flight fetch deletes that fetch's temp file, so `commit`'s rename fails and the download errors. `CAIRN_CACHE_MIN_AGE` is applied only to blobs, not partials, so even a temp file created seconds before is destroyed.\n\n🟠 `bug` services/proxy/src/sweep.rs:140: `forget(&index, &gone)` runs unconditionally, but `gone` is populated on dry runs too (line 137). A dry run — documented in docs/operations.md and on the route as reporting \"without removing anything\" — deletes the index entries of every blob it would have removed, degrading those coordinates to a miss-and-refetch the next time they are requested.\n\n🟠 `bug` services/proxy/src/routes/admin.rs:76: the on-demand handler calls `app.sweeper.sweep(dry_run)` directly instead of `run()`, so it never takes the `running` mutex (sweep.rs:83) and can run concurrently with the 15-minute background sweep in main.rs:116 — the exact two-sweeps-over-one-directory hazard the module doc (sweep.rs:10-12, 65-67) claims the type prevents. Both compute `held` from the same starting total and remove independently, driving the store far below the ceiling and double-counting reclaimed bytes.\n\n🟡 `bug` services/proxy/src/routes/admin.rs:76: `Sweeper::sweep` is a synchronous recursive walk plus per-blob unlinks, executed directly on a tokio worker thread — both here and via `run()` awaited in the spawned task (main.rs:116). On a store of the size the module's own doc contemplates (65k leaf directories, sweep.rs:15), one sweep stalls a runtime worker for the duration, delaying every request multiplexed onto it. The sync-walk choice is defensible; running it outside `spawn_blocking` is the defect.\n\n🔵 `bug` services/proxy/src/sweep.rs:130: when `fs::remove_file` fails, the candidate is still counted into `removed`, `bytes`, and `gone`, and its index entries are then deleted by `forget`. A persistent failure (permissions, read-only mount) inflates `sweep_bytes_reclaimed_total` on every sweep with bytes never reclaimed, and drops index entries for blobs that still exist, forcing a refetch of bytes that were present.\n\n🔵 `bug` services/proxy/src/sweep.rs:205: an index entry that fails to read or parse is skipped, which leaves its digest absent from the `index` map — so the blob it points at satisfies `!index.contains_key(hex)` (line 119) and is deleted. This is the opposite of the comment's stated intent (\"deciding here that it references no blob would delete the bytes that refetch is about to find\"); the consequence is one refetch per occurrence, tolerable but not what the code says it does.","auth":{"mode":"api_key"},"effort":"high","elapsed_secs":325.311,"error":null,"error_kind":null,"instructions":[],"model":"z-ai/glm-5.3-flash","ok":true,"sandbox":{"backend":"macOS Seatbelt","denied_read_roots":[],"environment":["HOME","LANG","LC_ALL","PATH","TERM","TMPDIR"],"mode":"read-only","network":"denied","protected_write_roots":["/Users/bart.smykla@konghq.com/Projects/github.com/smykla-skalski/benchee/.git","/Users/bart.smykla@konghq.com/Projects/github.com/smykla-skalski/benchee/.afi","/Users/bart.smykla@konghq.com/Projects/github.com/smykla-skalski/benchee/.agents","/Users/bart.smykla@konghq.com/Projects/github.com/smykla-skalski/benchee/.codex","/Users/bart.smykla@konghq.com/Projects/github.com/smykla-skalski/benchee/AGENTS.md","/Users/bart.smykla@konghq.com/Projects/github.com/smykla-skalski/benchee/CLAUDE.md"],"readable_paths":["/"],"readable_roots":["/Users/bart.smykla@konghq.com/Projects/github.com/smykla-skalski/benchee","/Users/bart.smykla@konghq.com/Projects/github.com/smykla-skalski/benchee/.git","/bin","/sbin","/usr/bin","/usr/sbin","/usr/lib","/usr/libexec","/usr/share","/System/Library","/Library/Apple","/Library/Filesystems/NetFSPlugins","/Library/Preferences","/private/etc","/private/var/db/timezone","/private/var/db/DarwinDirectory/local/recordStore.data","/private/var/select/developer_dir","/private/var/select/sh","/opt/homebrew/bin","/opt/homebrew/Cellar","/opt/homebrew/etc/gitconfig","/opt/homebrew/lib","/opt/homebrew/opt","/usr/local/bin","/Applications/Xcode.app/Contents/Developer","/Applications/Xcode.app/Contents","/Users/bart.smykla@konghq.com/.local/bin/afi"],"writable_roots":["/private/var/folders/d1/tvmyp5cs1gz38rltf390ddpw0000gn/T/afi-sandbox-JVZHtY"]},"schema_version":1,"source":"openrouter","sources":[{"auth":{"mode":"api_key"},"source":"openrouter","usage":{"cache_read_tokens":75776,"cache_write_tokens":0,"cost_usd":0.023679,"estimated_tokens":0,"input_tokens":73367,"output_tokens":733,"reasoning_tokens":20633,"requests":6,"total_tokens":170509}}],"system_prompt":{"file":null,"mode":"builtin"},"tools":["read_file","write_file","edit_file","list_dir","search_files","glob_files","run_bash","wait_background"],"usage":{"cache_read_tokens":75776,"cache_write_tokens":0,"cost_usd":0.023679,"estimated_tokens":0,"input_tokens":73367,"output_tokens":733,"reasoning_tokens":20633,"refused_by_approval":0,"refused_by_policy":0,"refused_tool_calls":0,"requests":6,"total_tokens":170509}}