feat(analytics): analytics subcommand group (digest shim, quiet, trends)

[mvanhorn]

Summary

Introduces discrawl analytics as a namespace for activity-style queries. Three subcommands ship:

• analytics digest - delegates to the existing digest implementation, so discrawl digest is unchanged
• analytics quiet - channels with no activity in the lookback window (archive candidates), default --since 30d
• analytics trends - week-bucketed message counts per channel, zero-filled across the window, default --weeks 8

Ports vincentkoc/slacrawl#13 (merged 2026-04-23). Same SQL recipes adapted to discrawl's Discord schema.

Stacking

This PR is stacked on top of #46 (feat(cli): digest command). Until #46 merges, the diff here includes both sets of changes. Once #46 lands, this PR narrows to just the analytics work. Happy to wait for #46 review before this one moves; happy to combine into a single PR if that is preferred.

Why this matters

• Issue Using discrawl as memory augmentation for AI agents #15 (@codexGW's writeup) describes building three Discord bots on top of discrawl with custom Python that asks two questions discrawl currently has no built-in answer for: which channels are silent, and how is volume changing week over week. quiet and trends answer them.
• discrawl already has the schema, indexes (idx_messages_guild_created_id), and the internal/report/ package needed. The SQL is one query each; no schema changes.
• Discord's own UI does not show silent-channel discovery or week-over-week volume per channel. The local archive is in a strictly better position to answer both.

Output

$ discrawl analytics quiet --since 30d

Quiet channels (no activity in the last 30d)

  bot-test       (text)        last: never       silent: -
  releases       (text)        last: 2026-03-10  silent: 46d
  off-topic      (text)        last: 2026-03-22  silent: 34d

Totals: 3 channels

$ discrawl analytics trends --weeks 4

Channel       Wk1   Wk2   Wk3   Wk4
general        12    18    24    31
incidents       3     1     -     7
releases        -     -     -     2
off-topic       8     5     2     -

Window: 2026-03-28 to 2026-04-25

$ discrawl analytics
Usage: discrawl analytics <subcommand> [flags]

Subcommands:
  digest  Per-channel activity summary for a window.
  quiet   Channels with no activity in the lookback window.
  trends  Week-over-week message counts per channel.

Flags

• analytics quiet: --since (default 30d), --guild. Inherits --json and --plain from the root CLI.
• analytics trends: --weeks (default 8), --guild, --channel. Same root-CLI inheritance.
• analytics digest: same flags as digest (delegates to runDigest, identical behavior).

Scope

• No schema changes. Uses existing messages / channels tables.
• No new dependencies.
• Both quiet and trends filter to message-bearing channel kinds (text, announcement, thread_public, thread_private, thread_announcement) so category and voice channels do not appear as never-active or all-zero rows. Mirrors the syncer's messageChannelKinds() predicate.
• New: internal/report/quiet.go, internal/report/quiet_test.go, internal/report/trends.go, internal/report/trends_test.go, internal/cli/analytics.go, internal/cli/analytics_test.go.
• Touched: internal/cli/cli.go (one switch case), internal/cli/output.go (printPlain + printHuman cases for Quiet and Trends, plus analytics in usage), README.md, SPEC.md.

Test plan

• gofmt -l . clean
• go vet ./... clean
• go build ./cmd/discrawl
• go test ./... passes (11 packages, all green)

Self-reviewed via codex review before pushing. The first review pass flagged that quiet and trends would surface category and voice channels as never-active, which would be misleading. Fixed in a follow-up commit on this branch by adding the kind filter described in Scope.

Open questions

1. Namespace name: analytics vs insights vs stats. Slacrawl went with analytics; happy to rename.
2. internal/report/ vs new internal/analytics/ package: kept everything in internal/report/ alongside report.go and digest.go to match the current organization. If you would prefer to carve out an internal/analytics/ package, easy follow-up PR.
3. Default --since for quiet: went with 30d (slacrawl's default). For Discord's larger guilds with many low-activity channels, 60d or 90d may be more useful. Happy to change.
4. quiet order: zero-activity (silent: -) first, then by name alphabetically. The slacrawl version sorts by last-message ascending which puts oldest first; this implementation puts never-active first since they are the strongest archive candidates. Happy to flip if you prefer slacrawl's ordering.

Subsequent phases (not in this PR)

Slacrawl's plan doc had health and response-times as phase 3, then threads-stale and activity as phase 4. Same idea here; happy to follow up if these land well.

This contribution was developed with AI assistance.

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