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feat(chapel): --scheduler flag with dual-direction startup banner
Adds the first-class scheduler choice to mass-panic ahead of the queue-scheduler implementation landing. The flag + dual-direction banner goes in now so that: * Operators running static mode see the tradeoff they're accepting at run time — crash/Ctrl+C loses progress — rather than discovering it the hard way after an interrupted sweep. * Operators asking for resumable runs with --scheduler=queue get a clean actionable bail-out, not a silent fall-back to static (which would violate their stated intent). * Any tooling that pins --scheduler=queue can be written against today's CLI and stay valid once the queue path lands. Implementation: * `config const scheduler: string = "static"` — "static" | "queue" * `config const resume: bool = false` — only valid with queue * `selectAndAnnounceScheduler(): bool` — validates flag value, prints the banner appropriate for the chosen mode (or prints an error + returns false for queue/unknown). Called before repo discovery so bail-out is cheap. * Static banner explains the default, calls out no-resume, and points at --scheduler=queue as the alternative. * Queue bail-out names the design (atomic work-pull + JSONL journal shards per locale, --resume skips "done" repos), points at chapel/README.md §Scheduling modes and ROADMAP.adoc v3.0.0, and lists two workarounds (retry under static, or use the Rust assemblyline path single-machine). * `--quiet` suppresses the static banner as it already suppresses other startup chatter. * --resume under static mode gets a WARNING rather than a silent no-op. Docs: * chapel/README.md — new §Scheduling modes with static vs queue comparison, "why not default to queue", current-status note ("queue is v3.0.0; flag accepted today for CLI stability"), and the exact banner strings operators will see. * chapel/README.md options table — new rows for --scheduler and --resume. * ROADMAP.adoc v3.0.0 — queue scheduler bullet with full design sketch and the note that the flag + banner are already wired. No existing behaviour changes. --scheduler omitted is equivalent to --scheduler=static which is the current round-robin + coforall path; only a new banner fires. `--scheduler=queue` returns non-zero from main() instead of scanning. Not build-tested — no chpl compiler on this machine. The change is syntactically conservative (config const + bool-returning proc + writeln) and models existing file style; any syntax slip will surface immediately on the next Chapel build. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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‎ROADMAP.adoc‎

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@@ -185,6 +185,7 @@ but panic-attack flags these as generic UnsafeCode findings.
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* [ ] Per-node temporal diff: load full SystemImage JSON for per-repo health breakdown
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* [ ] Multi-machine orchestration: gasnet/ofi multi-locale Chapel run across cluster nodes
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* [ ] VeriSimDB HTTP push from Chapel metalayer (currently file-only)
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* [ ] `--scheduler=queue` — resumable dynamic work-pull scheduler for mass-panic. Atomic fetch-add work index shared across locales; per-locale JSONL journal shards recording `{claim, done}` state per repo; `--resume` skips any repo already marked `done`. ~5–15% slower than static on clean runs, survives mid-sweep crashes and Ctrl+C. Flag and both-directions banner already wired (2026-04-17); queue path targeted for v3.0.0. See `chapel/README.md` §Scheduling modes for the full spec.
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== v3.1.0 -- Ecosystem Integration
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‎chapel/README.md‎

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@@ -69,6 +69,8 @@ chpl src/MassPanic.chpl src/Protocol.chpl src/Imaging.chpl src/Temporal.chpl -o
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| `--repoDirectory` | | Directory to scan for .git repos |
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| `--panicAttackBin` | `panic-attack` | Path to panic-attack binary |
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| `--mode` | `assail` | Operation mode (see above) |
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| `--scheduler` | `static` | `static` (fast, not resumable) or `queue` (resumable, ~5–15% slower — v3.0.0) |
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| `--resume` | `false` | Only with `--scheduler=queue`: skip repos already marked "done" in the journal |
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| `--incremental` | `true` | Skip unchanged repos via BLAKE3 |
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| `--cacheFile` | | Fingerprint cache file path |
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| `--outputDir` | `mass-panic-results` | Output directory |
@@ -79,7 +81,100 @@ chpl src/MassPanic.chpl src/Protocol.chpl src/Imaging.chpl src/Temporal.chpl -o
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| `--intensity` | `medium` | Attack intensity |
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| `--notify` | `false` | Generate notification summary |
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| `--panllExport` | `false` | Generate PanLL export files |
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| `--quiet` | `false` | Suppress progress output |
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| `--quiet` | `false` | Suppress progress output (also suppresses the scheduler banner) |
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## Scheduling modes
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The `--scheduler` flag is the first decision every `mass-panic` run
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implicitly makes. It controls **how work is distributed across
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locales**, and the tradeoff matters enough that the tool prints a
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banner in both directions at startup (unless `--quiet`) so operators
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don't lose overnight sweeps to a Ctrl+C they could have survived.
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### `--scheduler=static` — default
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Round-robin partition up-front, then `coforall` over Locales. Each
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locale gets its fixed list of repos and scans them in-order. This is
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the existing implementation and what every previous mass-panic
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release has done.
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- **Fast.** No per-repo overhead beyond the existing BLAKE3
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fingerprint cache. Chapel's `coforall` amortises scheduling cost
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across the whole range.
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- **Not resumable.** A locale crash, a Ctrl+C, or a single failed
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repo halfway through — all force restarting the whole run. The
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completed repos are in `mass-panic-results/assemblyline-*.json`
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but the coordinator hasn't yet merged them into the SystemImage.
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- **Right for:** scheduled nightly sweeps over a stable corpus,
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where the run finishes before anyone touches the terminal.
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### `--scheduler=queue` — planned, v3.0.0
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Dynamic work-pull via a shared atomic counter plus a per-locale
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JSONL journal shard. Each locale claims the next unclaimed repo
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from a shared counter, writes a `{"state":"claim", …}` entry to
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its shard, runs the scan, writes `{"state":"done", …}`.
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`--resume` reads every shard, builds the set of fingerprints
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already marked `done`, and skips them — so an interrupted run
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picks up where it left off.
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- **Resumable.** Ctrl+C at t=3h drops ~1 repo of work; the next
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invocation with `--resume` reuses everything completed so far.
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A locale crash during a multi-day sweep loses only the
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currently-in-flight repo on that locale.
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- **~5–15% slower** on clean runs. The dispatch overhead per task
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(atomic fetch-add + one journal write) is per-repo instead of
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being amortised across a `coforall` range. On a clean 10k-repo
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sweep, expect queue mode to finish in ~1.10× the time of static.
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- **Right for:** long interactive sweeps (GitHub-account scale or
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larger), sweeps where at least one locale is on spot/preemptible
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infrastructure, or any run where you expect to want to pause
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and come back.
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#### Why not make queue mode the default?
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Static mode is measurably faster on clean runs and doesn't require
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any durable state. If your run always finishes cleanly, the journal
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writes are wasted I/O. Making the default explicit ("you are in
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static mode; here is what you're giving up") lets operators make
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that call consciously instead of paying for resilience they don't
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need.
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#### Current status
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`--scheduler=static` is implemented and is the existing behaviour.
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`--scheduler=queue` exits with an actionable error message pointing
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at this section and `ROADMAP.adoc` (targeted v3.0.0). The flag is
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already accepted today so that (a) any tooling that pins `--scheduler=queue`
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has a stable CLI contract to write against, and (b) the bail-out is
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noisy rather than silent — an operator who asked for resumable
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runs must not get a non-resumable one without consent.
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### Startup banner
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When you run `./mass-panic …`, the scheduler banner appears before
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repo discovery:
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```
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mass-panic: scheduler=static (default)
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fastest on clean runs; no --resume support.
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A crash or Ctrl+C loses all progress.
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Use --scheduler=queue for resumable runs (when available, ~5-15% slower).
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```
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Or, if you attempt queue mode today:
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```
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mass-panic: ERROR: --scheduler=queue is not yet implemented.
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Design: atomic work-pull + JSONL journal shards per locale, --resume skips any repo already
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marked "done". See chapel/README.md §Scheduling modes for the full spec and ROADMAP.adoc for
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the targeted landing (v3.0.0).
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Options while you wait: rerun after a crash with --scheduler=static (no incremental state), or use
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the Rust `panic-attack assemblyline` path on a single machine where Ctrl+C is rarer.
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```
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The banner is suppressed under `--quiet`.
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## Output
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‎chapel/src/MassPanic.chpl‎

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@@ -94,6 +94,34 @@ module MassPanic {
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// PanLL export alongside raw output
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config const panllExport: bool = false;
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// Scheduler — controls how work is distributed across locales.
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//
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// "static" (default)
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// Round-robin partition + `coforall` over Locales. Fast, clean,
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// but a mid-scan crash loses progress — the whole run must be
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// restarted because no per-repo state is durably recorded.
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// Best for scheduled nightly sweeps over stable corpora.
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//
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// "queue" (planned, v3.0.0 — see chapel/README.md §Scheduling modes)
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// Dynamic work-pull via a shared atomic counter + JSONL journal.
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// Each locale claims the next unclaimed repo, writes a "claim"
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// entry to a per-locale journal shard, scans, writes "done".
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// `--resume` reads all shards and skips completed repos.
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// ~5–15% slower than static on clean runs; survives mid-scan
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// crashes and Ctrl+C without losing completed work. Best for
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// long interactive sweeps where you might hit a locale timeout
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// or want to pause and resume.
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//
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// When the queue implementation lands, selecting it will NOT make
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// the static mode slower — the existing static path stays exactly
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// as it is. The flag is additive.
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config const scheduler: string = "static";
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// Resume from a previous --scheduler=queue run by skipping any repo
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// already marked "done" in the journal. Only meaningful with
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// --scheduler=queue; ignored (with a warning) in static mode.
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config const resume: bool = false;
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// ---------------------------------------------------------------------------
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// Entry point
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// ---------------------------------------------------------------------------
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return;
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}
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// Validate --scheduler and print the running-mode banner. Both
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// modes get an explicit banner (not only the non-default one)
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// because the tradeoff is real in both directions — static is
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// fast but not resumable; queue is resumable but slower. See
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// chapel/README.md §Scheduling modes for the full discussion.
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if !selectAndAnnounceScheduler() then return;
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const startTime = timeSinceEpoch().totalSeconds();
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// Discover repositories
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printSummary(report, image);
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}
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// ---------------------------------------------------------------------------
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// Scheduler selection — validate --scheduler and print the
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// running-mode banner in both directions. See chapel/README.md
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// §Scheduling modes for the full tradeoff discussion.
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//
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// Why both modes get a banner (not only the non-default one):
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//
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// The static default is fast and ergonomically invisible, but
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// its non-resumability is a real correctness property of the run
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// — operators need to *know* that a Ctrl+C at t=3h is wasted
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// work. Silently accepting the default is how people lose
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// overnight sweeps and don't realise until morning.
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//
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// The queue mode pays a ~5–15% throughput tax for resilience,
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// so we tell operators running that path that they are trading
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// clean-run speed for crash recovery. If their run completes
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// cleanly they might prefer static next time.
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//
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// The banner is suppressed under --quiet, along with everything
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// else.
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// ---------------------------------------------------------------------------
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// Returns true if mass-panic should proceed with scanning, false
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// if it should bail cleanly. Writing the banner/error messages is
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// the side effect.
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proc selectAndAnnounceScheduler(): bool {
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if scheduler == "static" {
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if !quiet {
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writeln("mass-panic: scheduler=static (default)");
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writeln(" fastest on clean runs; no --resume support.");
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writeln(" A crash or Ctrl+C loses all progress.");
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writeln(" Use --scheduler=queue for resumable runs ",
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"(when available, ~5-15% slower).");
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}
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if resume {
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writeln("mass-panic: WARNING: --resume ignored — ",
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"requires --scheduler=queue");
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}
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return true;
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} else if scheduler == "queue" {
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// The queue scheduler is a planned v3.0.0 feature — the
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// flag is already accepted here so the UX is stable when
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// the implementation lands, and so any tooling pinning
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// --scheduler=queue can be written against today's CLI.
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//
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// Bailing out with a clear actionable message is strictly
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// better than silently falling back to static — an
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// operator who asked for resumable runs must not get a
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// non-resumable one without consent.
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writeln("mass-panic: ERROR: --scheduler=queue is not yet implemented.");
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writeln(" Design: atomic work-pull + JSONL journal ",
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"shards per locale, --resume skips any repo already");
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writeln(" marked \"done\". See ",
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"chapel/README.md §Scheduling modes for the full spec ",
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"and ROADMAP.adoc for the targeted landing (v3.0.0).");
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writeln(" Options while you wait: rerun after a crash ",
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"with --scheduler=static (no incremental state), or use");
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writeln(" the Rust `panic-attack assemblyline` path ",
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"on a single machine where Ctrl+C is rarer.");
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return false;
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} else {
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writeln("mass-panic: ERROR: unknown --scheduler=", scheduler,
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" — expected 'static' or 'queue'");
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return false;
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}
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}
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// ---------------------------------------------------------------------------
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// Diff subcommand — compare two temporal snapshots
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// ---------------------------------------------------------------------------

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