sandbox:read-only (macOS Seatbelt) -- reasoning -- I'm spotting a couple bugs in the repo: metrics.rs has a values() ordering mismatch where the counters list and returned values are swapped, and sweep.rs uses a `>=` comparison against max_bytes that likely causes it to remove one extra item when the remaining size exactly equals the max. More critically, the admin route calls `app.sweeper.sweep(dry_run)` directly instead of going through `run()`, bypassing the mutex that's supposed to enforce one sweep at a time — and this also blocks the async runtime thread. Even worse, `forget(&index, &gone)` is called unconditionally, meaning a dry run still deletes index entries from the store, which defeats the whole purpose of dry_run. Finally, the candidate sort by age is ascending, so despite the "oldest first" comment, it actually evicts the newest blobs first — a serious logic inversion. I'm now questioning whether unreferenced blob removal could race with concurrent writes: if the store writes the blob before the index entry, a sweep running concurrently could delete a blob that was just written but not yet indexed, so I need to check store.rs for that ordering. I'm also second-guessing whether `Duration::from_hours`/`from_mins` are actually stable in the Rust version being targeted, since I recall these constructors landed in a fairly recent stabilization. Beyond that, I'm noting some minor validation gaps around cache_max_bytes and cache_min_age, and flagging that `spawn_sweeps` calls into a fully synchronous sweep routine from an async context without wrapping it in spawn_blocking, which could stall the runtime's worker thread during a long sweep despite the module's justification for staying synchronous. router still looks fine there. But I'm now spotting a real concurrency issue: `clear_partials` deletes all files in the incoming directory indiscriminately, which could hit a temp file belonging to an in-flight fetch that's still being written—on Unix the unlink would succeed while the writer's fd stays open, but the eventual rename would then fail with ENOENT, breaking that fetch. That's worth flagging as a genuine bug since it should be gated by an age threshold instead. Now I want to actually go read the source files—store.rs, config.rs, routes/admin.rs, metrics.rs, sweep.rs, and main—to verify these suspicions against the real code. I'll start by finding the proxy sources the diff touches. └ 2031 tok · 71.8 tok/s · 19K ctx · 4869ms ttft · 28.3s wall ↳ glob_files: glob services/proxy/**/*.rs in pr └ glob_files: glob complete ↳ read_file: read pr/services/proxy/src/sweep.rs └ read_file: read complete ↳ read_file: read pr/services/proxy/src/metrics.rs └ read_file: read complete ↳ read_file: read pr/services/proxy/src/routes/admin.rs └ read_file: read complete auto-compress is on at 85% but the context window of "anthropic/claude-opus-5" on openrouter is unknown, so this run will not compress - set AFI_SOURCE_OPENROUTER_CONTEXT_WINDOW (or pass --context-window) to enable it -- reasoning -- I'm finding that metrics.rs has the two counters swapped in the exposition since COUNTERS order doesn't match the values() order—a definite bug. I'm also noticing sweep.rs sorts by age ascending, which actually removes the newest blobs first despite the comment claiming "oldest first," meaning eviction targets the wrong entries. Additionally, I'm spotting a minor off-by-one where `remaining >= max_bytes` should be `>`, and a more serious issue: the admin route calls `sweeper.sweep()` directly and synchronously, bypassing the mutex that's supposed to prevent concurrent sweeps, while also blocking the async runtime thread with sync fs I/O. But the real critical bug is that `forget` runs unconditionally even during dry runs — so `?dry_run=true` actually deletes index entries for real, causing cache misses in production. And `clear_partials` doesn't check age at all, meaning a sweep can delete the temp file of a download that's actively in progress since it does no min_age check on partial files. There's also a concurrency issue: `spawn_sweeps` calls a blocking synchronous filesystem walk directly inside a tokio task instead of using `spawn_blocking`, which stalls a runtime worker thread. And I'm noticing the config uses unstable Duration constructor APIs that wouldn't even compile on stable Rust. I still need to check how the store lays out blob paths to confirm the hex/filename handling is correct. Also the `dry_run` query bool likely only parses "true"/"false" strings, so a bare `?dry_run` param would 400 — minor issue but rejection happens pre-auth, which seems acceptable. Let me actually dig into store.rs, config.rs, routes/cache.rs, and main.rs now. Now the store layout and config, to check the digest/index assumptions and the duration constructors. └ 1845 tok · 73.7 tok/s · 28K ctx · 3872ms ttft · 25.0s wall ↳ read_file: read pr/services/proxy/src/store.rs └ read_file: read complete ↳ read_file: read pr/services/proxy/src/config.rs └ read_file: read complete ↳ read_file: read pr/services/proxy/src/main.rs └ read_file: read complete ↳ read_file: read pr/services/proxy/src/routes/cache.rs └ read_file: read complete -- reasoning -- I'm finding two real bugs: in metrics.rs, the values() order swaps blobs_removed and bytes_reclaimed against COUNTERS, so metrics get rendered under the wrong names. In sweep.rs, sort_by_key(age) sorts ascending, meaning youngest blobs get evicted first even though the comment claims "oldest first" — the sort should be reversed. There's also an off-by-one where remaining >= self.max_bytes evicts one blob too many at the exact ceiling, though that's minor. More seriously, dry_run mode still calls forget() unconditionally, so a dry-run sweep actually deletes index entries and causes cache misses — that's a genuine correctness bug. I'm also noticing that routes/admin.rs calls sweeper.sweep() directly without going through the mutex guarding concurrent sweeps, breaking the "one sweep at a time" guarantee, and the synchronous filesystem walk runs blocking on the async runtime's worker thread. The synchronous sweep runs directly on an async task without spawn_blocking, blocking the tokio worker thread for the whole sweep duration — main.rs's spawn_sweeps calls run().await inside a task, which stalls the runtime. That admin route bypass also means the admin-triggered sweep can run concurrently with the background one, violating the module's own documented invariant. There's also a race where clear_partials wipes everything in the incoming directory, including partial writes from in-flight downloads, so an active fetch's temp file gets unlinked mid-write and the subsequent rename to the final path fails with ENOENT, breaking that fetch. Actually, checking further, `Duration::from_mins`/`from_hours` are already used elsewhere in the config tests in this repo, so they clearly compile here—not a new defect, just something to note rather than flag as an issue. Moving on: held counts only blobs, not index/incoming, which seems fine, and the sweeper's handling of shortened leaf names looks fine too. The bigger issue is that unreferenced blob removal ignores min_age, and combined with the fetch path ordering—where the blob gets committed to blobs/ before the index entry is linked—there's a window where a blob could be swept before it's properly referenced. Tracing through fetch: commit happens first, then register_version does a network round trip, then link writes the index entry last. Since open_blob happens after fetch returns, a sweep running in that window could delete the just-committed blob, causing the request to fail with a "blob missing from store" error. This is a genuine race worth flagging, pointing at sweep.rs around lines 119-120 and cache.rs line 151—the unreferenced removal ignoring min_age is what makes this dangerous. The metrics counter name/help pairing for bytes looks fine. Now I'm checking where the sweep route gets registered in the router. Checking a few more things: the admin purge route has a timeout, invalid query params on dry_run just return a 400 before authorization (minor, not really an info leak), the sweep route does authorize despite being a POST, unauthenticated timing looks fine, error response conversion is fine, and the untimed router doesn't need a body-limit here. The Reclaimed serialization looks fine, and spawning sweeps before axum::serve in main.rs is the correct order. Now I'm looking at how sweep.rs collects candidates. I notice it uses fs::metadata, which follows symlinks rather than symlink_metadata, which doesn't -- the comment about "a link is counted at the size of the link" suggests the author meant something like a hard link scenario where metadata gives real size. But this raises a real concern: if a symlink to a directory exists inside the blob dir, following it during recursive collection could cause infinite recursion or even let deletion escape outside the store directory. I'm now wondering who could actually place a symlink there in practice. I check the dry-run behavior for clear_partials -- it counts files without removing them, which looks fine, and held/etc behave correctly in dry-run mode too. The record_sweep call passes matching arguments for blobs and bytes count, so that's fine. Now I'm noticing a bigger issue: sweep() runs synchronously but gets called from an async handler in admin.rs, meaning a full filesystem walk over potentially millions of files could block the async worker thread entirely. I look for justification of sync-vs-tokio::fs elsewhere in the code, but nothing addresses using spawn_blocking to avoid this, so I flag it as a performance concern. There's also a tokio Mutex held across this blocking call in run(), which compounds the blocking issue even though it's technically correct. Checking the removal loop logic -- the condition rechecks `remaining >= self.max_bytes` each iteration, so it correctly stops removing once under the threshold. The forget-on-store-over-ceiling behavior also looks correct, properly removing index entries for blobs that get removed. But I notice forget gets called even when removals fail. The error path is problematic: bytes/removed counts get incremented even when fs::remove_file fails, inflating the reclaimed metric. For ENOENT that's harmless, but for EACCES/EBUSY it falsely reports bytes as reclaimed and drops the index entry for a blob that's still actually present, causing an unnecessary refetch later. That's a yellow-level issue worth flagging, and it also affects the metric documented in operations.md. Double-checking the sort ordering claim -- sort_by_key ascending means smallest age comes first, meaning most recently modified files are sorted to the front. Then the removal loop removes those front-of-list entries first while over the ceiling, which means it evicts the newest blobs rather than the oldest -- this inverts LRU and actively evicts things that were just fetched. Since freshly-fetched blobs fall under min_age, the `age >= min_age` check skips anything under an hour old, so it ends up removing the just-over-an-hour blobs first instead, but the eviction order is still inverted overall -- this is a real bug, red or orange severity. I'm also confirming CAIRN_CACHE_MIN_AGE=1h in .env.example is fine, and noting the docs claim about sweeps clearing partial writes from dead fetches ties into a separate item. There's also no validation that cache_max_bytes is at least max_artifact_bytes, but that's minor and I'll skip flagging it. Now I want to check whether there's a test file covering sweep behavior, and verify the proxy's Cargo.toml enables the derive feature for serde since sweep code uses Serialize. Let me check the proxy's Cargo.toml deps and any tests covering the sweep. └ 3707 tok · 70.9 tok/s · 47K ctx · 4717ms ttft · 52.3s wall ↳ read_file: read pr/services/proxy/Cargo.toml └ read_file: read complete ↳ glob_files: glob services/proxy/**/* in pr └ glob_files: glob complete -- reasoning -- I'm cataloging the bugs I've found. First, there's a mismatch in metrics.rs where the COUNTERS list order doesn't match the values() return order, so counts get rendered under the wrong labels. Second, I'm checking sweep.rs's sort_by_key on age, which sorts ascending—meaning it orders newest-first rather than oldest-first as intended. Given the ascending sort, the eviction loop actually removes the newest blobs first instead of respecting LRU order, and the fix should be sorting descending by age. I'm also noting the `remaining >= max_bytes` comparison is an off-by-one that evicts one extra blob at the exact ceiling, and that admin::sweep calls the blocking sweep directly on the async runtime thread while also bypassing the running Mutex, breaking the documented one-at-a-time guarantee since the on-demand route can run concurrently with the background sweep. Both the background task and the route handler block a worker thread synchronously instead of using spawn_blocking, which is a real performance concern for route handlers. More seriously, I'm seeing that `sweep(dry_run)` calls forget unconditionally even in dry-run mode, meaning a dry run actually deletes index entries and loses cache data — that's a critical bug. I'm now looking at whether clear_partials removes incoming files unconditionally too. Since BlobWriter writes into incoming while a fetch is in progress, a sweep could delete an in-flight file mid-download — unlinking doesn't stop the write on Unix, but the later rename during commit fails with NotFound, causing the fetch to error out even though nothing was actually wrong. This contradicts the module's own claim that files in incoming are abandoned fetches; concurrent large downloads can be killed by a sweep, which I'd rate high severity, especially with two proxies sharing a directory. I'm now looking at how `referenced()` uses collect() to compute something related to age. I'm also checking whether `Duration::from_hours`/`from_mins` are stable in the current Rust toolchain, since they're behind the unstable `duration_constructors` feature — but I notice the existing test code already uses these methods, so the crate must already assume a toolchain where they're stabilized, meaning this isn't a new issue introduced by the diff. I'm also confirming that dry-run logic in `clear_partials` reports removals accurately, and that main.rs runs sweeps through the mutex-holding `sweeper.run()` — though I want to check whether the admin route bypasses this locking and whether the sweep route sits outside the timeout layer given the merged router setup. Now I'm digging into a real bug: when `fs::remove_file` fails, the code only logs the error but still counts the file as reclaimed bytes/removed and deletes its index entry — so a permission-denied blob falsely reduces the "remaining" total, causing the sweep to stop early while disk usage stays high, and triggering unnecessary refetches since the index thinks the blob is gone. I'm noting this contrasts with `clear_partials`, which correctly skips counting on error, making the inconsistency clear evidence of a real defect. Checking other smaller things: the metrics recording signature looks fine, `held` correctly excludes partials, and the dry_run query parsing via `Query` with serde defaults works as documented, though malformed values just get axum's generic 400 rather than a custom error — minor, not worth flagging. I'm also glancing at extractor ordering in the sweep handler to make sure everything but the last argument implements `FromRequestParts` per axum 0.8 rules. I'm also checking that authorization happens before the sweep logic runs, that the removal loop correctly stops once remaining drops below max_bytes, that indexed candidates properly include nested files, and that a race where a blob gets removed between resolve and open is safely treated as a miss. There's a more serious race though: the sweep deletes any blob not in the index unconditionally, but a blob just committed by an in-flight fetch won't be indexed until link() runs later — and that link happens after a network round-trip to register_version. If a sweep runs during that window, it deletes the blob before linking completes, and when the handler later calls open_blob it finds the blob missing and returns a 500 storage error, even though the request itself just committed that blob. This is the same underlying defect as the partials issue: sweep.rs:119's unreferenced-blob deletion ignores min_age entirely — the comment even states age doesn't matter there — while min_age is only respected in the over-ceiling branch. That's the real bug to flag, pointing at sweep.rs:119 alongside cache.rs:151-163, and I'd call it a high-severity finding. I'm also skimming through the rest for smaller issues: docs corroborating the same sweep behavior, config defaults, metrics counts, serialization/logging traits, spawn ordering in main.rs, and the routes doc's claim about route counts — nothing else jumps out as significant so far. └ 3534 tok · 74.1 tok/s · 49K ctx · 3914ms ttft · 47.7s wall ↳ read_file: read pr/services/proxy/src/routes/mod.rs └ read_file: read complete ↳ read_file: read pr/services/proxy/src/digest.rs └ read_file: read complete -- reasoning -- I'm spotting a metrics ordering bug: the COUNTERS list has sweep_blobs_removed_total and sweep_bytes_reclaimed_total swapped relative to the order values() returns them, so they'd get reported under the wrong names. Next I notice the admin sweep route calls sweeper.sweep(dry_run) directly instead of run(), bypassing the mutex that's supposed to guarantee only one sweep runs at a time — so a concurrent HTTP-triggered sweep and background sweep could interleave. I'm also realizing both run() and the admin route perform the filesystem walk synchronously inside an async context without spawn_blocking, which would stall a tokio worker thread during a large store walk and block other requests like downloads — a real performance defect in both main.rs and admin.rs. Now I'm looking at how candidates get sorted and filtered against min_age before removal. But then I catch a serious inverted-logic bug: sorting by ascending age actually puts the newest blobs first, contradicting the "oldest first" comment — so the sweep evicts the youngest blobs above the min_age threshold while preserving the truly old ones, which is the opposite of proper LRU eviction. That needs to be reversed to sort by descending age, and I'd call this a high-severity issue. There's also a minor off-by-one where the eviction condition uses >= instead of > against max_bytes, causing it to remove one extra blob when storage sits exactly at the ceiling — low severity but worth flagging. Now the biggest finding: `clear_partials` unconditionally deletes everything in `incoming/`, but that directory holds temp files for fetches actively in progress, not abandoned ones as the doc claims. Since there's no age check at all here (unlike the min_age guard for blobs), a concurrent download's temp file can get unlinked mid-write, causing the later rename-to-commit to fail with ENOENT and the client's fetch to error out — this is a real race condition bug, not just a stylistic issue. I'm also noting a second issue in `forget`: it pushes to `gone` and tallies removed bytes/count regardless of whether `fs::remove_file` actually succeeded, so failures are silently swallowed and the sweep can misreport how much space was reclaimed and stop early. But the bigger finding is that `forget(&index, &gone)` at line 140 isn't gated behind `dry_run` at all — meaning a dry run still deletes index entries for blobs it would have removed, contradicting the documented "without removing anything" guarantee and causing real cache misses afterward. That's a clear red/orange bug at sweep.rs:140, distinct from the missing-guard issue found earlier. I'm also checking whether `Duration::from_hours`/`from_mins` are stable in the Rust version being used, since these constructors were unstable for a while under the `duration_constructors` feature. Actually, this seems already used in the existing test suite, so the toolchain must support it — not a real issue. I'm now noting that the `collect` function's use of `fs::metadata` actually follows symlinks rather than reporting the link itself, contradicting the comment that claims links are counted at their own size — this looks like a genuine bug, since a symlinked directory would get recursed into and a symlinked file removed incorrectly. But thinking more, the comment probably means "hard link" rather than symlink, since blobs are linked into place rather than copied. With hard links, `fs::metadata` reports the actual file size, so it's counted fully rather than at "the size of the link" — either way, the comment doesn't match reality. This leads to overestimating held space for hard-linked files, and a genuine symlink loop could cause infinite recursion, though that requires an actual symlink in the blob store. I'll flag this as a low-severity comment/behavior mismatch around sweep.rs:160-166 regarding symlink-following metadata. Looking at another case, when the store is over its ceiling but everything is younger than min_age, nothing gets removed — that's documented and not a bug. Now I'm looking at a potential race: a blob committed via `BlobWriter::commit` but not yet linked in the index (between the commit call, registry registration, and the actual link write) is technically unreferenced. If a sweep runs during that window, it could delete the blob before linking finishes, causing a later `open_blob` call to fail with a 500 error claiming the blob is already missing — this looks like a genuine race condition worth flagging. I notice the min_age guard that protects blobs on the ceiling-sweep path is deliberately absent on the unreferenced-blob path, which is exactly the kind of inconsistent check-on-one-path-but-not-another pattern that's worth flagging as orange or red severity. The remaining metrics and logging look consistent, and the operations doc's description of sweeps clearing partial fetch writes lines up with the bug I found. The sweep task setup before serving also looks fine on its own. Query extractor rejection returns a plain 400 rather than following the problem-document error format, which is a minor consistency issue, and I'm also noting that the rejection happens before authorisation—so unauthenticated callers just get a 400, not particularly impactful. There's also a small quirk where dry_run as a boolean query param only accepts "true"/"false" and rejects "1", which is a minor annoyance rather than a real bug. Checking the routing between the purge route (DELETE on a digest path) and sweep route (POST on a static path)—different HTTP methods mean no actual conflict, but I want to verify how matchit handles a static segment and a dynamic parameter occupying the same position when both routers get merged together. I'm confirming that matchit does support this sibling case. Checking a few more items: dry_run byte counts look correct and excluded from metrics, no duplicate metric recording in spawn_sweeps, and the tracing log order in admin.rs is fine since `reclaimed` is logged before being moved into the Json response. One minor note: the `sweep()` comparison against `max_bytes` only counts blob bytes, ignoring partials and index overhead. Now I'm re-verifying the sort direction bug — `sort_by_key` on age gives ascending order, so the most recently modified item comes first, contradicting the "oldest first" comment. That confirms the bug. I'm pinpointing the exact lines: the dry-run forget call needs a guard to skip execution when dry_run is set, and there's a related line that still pushes to the `gone` list even in dry-run mode, which is fine since that's just for reporting. For the partials race condition, I'm tracing it to two spots — one where the temp path is written to and linked, and another where the sweep unconditionally removes everything in the incoming directory. I'm confirming that BlobWriter's Drop implementation already cleans up partials for failed fetches, so the remaining files in incoming are either active writes or crash leftovers — this strengthens the case for a race there. I trace `link`'s temp path back to the same incoming directory, so if sweep deletes it mid-write between the write and rename steps, the link fails and the fetch returns an error despite the data being stored successfully. I'm now looking at a similar unreferenced-blob race involving the commit, registry call, and link steps in sequence, and how the referenced-check might read stale index state during that window. I trace this specific race to sweep's key check against the index, which removes entries with no consideration for age — a minimum-age threshold would have caught it, so I'll flag both the sweep and cache linking lines as an orange-severity issue. I also spot that the main sweep loop holds a mutex while the admin-triggered sweep doesn't, opening the door to concurrent sweeps running simultaneously, so I'll cite both locations. Separately, I notice the admin reclaim function runs a long synchronous filesystem walk directly inside an async handler rather than spawning it as a blocking task, which could stall a runtime worker thread — the same issue shows up in the background task, and it's worth flagging as a performance concern even though its severity depends on the runtime's thread pool size. I check that the module doc justifies its blocking calls but never actually offloads them, so I'll report this once pointing at the two call sites. Metrics recording in the background loop happening outside the lock looks fine, and the docs' claim about shared bearer tokens between the sweep and purge routes checks out. The example config's cache age and interval settings don't cross-validate against each other, which seems okay, but I do notice there's no check that the cache's max byte ceiling is at least as large as the maximum artifact size — if it's smaller, every sweep pass would wipe the whole cache, causing constant thrashing. It's a low-severity, somewhat speculative issue, so I'm debating whether it's worth including at all. I decide to skip that config-guard gap to keep the signal focused, and I confirm the missing zero-validation on the minimum cache age is actually fine since zero is a meaningful value there. The `must_use` attribute on the sweep function checks out too. Now I'm assigning severities: the partial-write deletion racing against in-flight fetches goes red since it can cause failed downloads, while the dry-run mode deleting index entries despite its promise not to is data-destructive in effect but only causes cache misses rather than actual data loss, so I'm leaning orange for that one. I'm continuing to work through severity ratings: the inverted sort that evicts newest entries and the unreferenced removal racing the commit-link step both get orange, as does the swapped counter values in metrics since an operator monitoring bytes reclaimed would actually see blob counts instead. The mutex bypass and blocking runtime issues get yellow, while the off-by-one comparison, miscounted bytes for failed unlinks, and the symlink-following metadata call with its wrong comment and potential infinite recursion on directory cycles all get blue. Now parse error: provider error: Network connection lost.