refactor: split .index file into multiple

[dkharms]

Description

This is first pull request of series #336. Changes in this pull request will allow us to efficiently merge several fractions into one when performing compaction.

So .index gets split into several:

• .info -- contains one info block;
• .offsets -- contains one block with offsets of DocBlock inside .docs file;
• .ids -- contains triplets of seq.MID, seq.RID and seq.DocPos blocks;
• .tokens -- contains tokens and token table;
• .lids -- contains chunks of seq.LID;

It's easy to notice that we expect increase in file descriptors usage by 3x

Several things I need to polish:

• Reintroduce statistics reporting on sealing;
• Backwards compatibility for sealed fractions which were offloaded to remote storage;
• Delete all sealed fractions files if at least one file has tmp suffix;
• Handle tmp .index files;

---

• I have read and followed all requirements in CONTRIBUTING.md;
• I used LLM/AI assistance to make this pull request;

If you have used LLM/AI assistance please provide model name and full prompt:

Model: Claude Sonnet 4.6
Context: I've used LLM to fix issues with index analyzer binary

[github-actions]

❌ PR Title Validation Failed
Please refer to CONTRIBUTING.md

[dkharms]

@seqbenchbot up main bulk

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

Your request was successfully served.
Identificator for your ongoing benchmark - f70e7779.

Here is a list of helpful links:

• Take a look at Grafana dashboard;
• Live-tailing logs are also available;

Have a great time!

[codecov-commenter]

Codecov Report

❌ Patch coverage is 62.85047% with 318 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.02%. Comparing base (fd721bd) to head (28053bf).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
frac/sealed_loader.go	41.86%	67 Missing and 8 partials ⚠️
frac/sealed.go	61.65%	33 Missing and 18 partials ⚠️
cmd/index_analyzer/main.go	0.00%	50 Missing ⚠️
frac/sealed/sealing/index.go	61.90%	12 Missing and 20 partials ⚠️
fracmanager/frac_manifest.go	58.10%	30 Missing and 1 partial ⚠️
frac/sealed/sealing/sealer.go	67.16%	14 Missing and 8 partials ⚠️
frac/remote.go	73.84%	8 Missing and 9 partials ⚠️
frac/sealed/sealing/writer.go	70.37%	8 Missing and 8 partials ⚠️
frac/sealed/sealing/blocks_builder.go	88.07%	7 Missing and 6 partials ⚠️
frac/active_sealing_source.go	84.05%	4 Missing and 7 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #389      +/-   ##
==========================================
- Coverage   71.41%   71.02%   -0.39%     
==========================================
  Files         210      210              
  Lines       15579    15849     +270     
==========================================
+ Hits        11125    11257     +132     
- Misses       3656     3779     +123     
- Partials      798      813      +15     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[dkharms]

@seqbenchbot down f70e7779

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

The benchmark with identificator f70e7779 was finished.
I've prepared a summary for you. Click on Show summary button to see it:

Show summary

Query	Type	mean (ms)			stddev (ms)			p(50) (ms)			p(95) (ms)			p(99) (ms)			iterations
		base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff
bulk	warm	75.47	75.95	+0.64%	31.14	32.51	+4.41%	67.00	66.00	-1.49%	140.00	144.00	+2.86%	191.00	196.00	+2.62%	56767.00	56645.00	-0.21%

Have a great time!

[dkharms]

@seqbenchbot up main mixed

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

Your request was successfully served.
Identificator for your ongoing benchmark - e47604c9.

Here is a list of helpful links:

• Take a look at Grafana dashboard;
• Live-tailing logs are also available;

Have a great time!

[dkharms]

@seqbenchbot down e47604c9

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

The benchmark with identificator e47604c9 was finished.
I've prepared a summary for you. Click on Show summary button to see it:

Show summary

Query	Type	mean (ms)			stddev (ms)			p(50) (ms)			p(95) (ms)			p(99) (ms)			iterations
		base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff
bulk	warm	75.44	75.74	+0.40%	30.28	30.81	+1.74%	67.00	68.00	+1.49%	136.50	140.00	+2.56%	188.00	191.00	+1.60%	21032.00	21063.00	+0.15%
service:payment-backend-eu AND k8s_namespace:prod AND level:[0 to 3] AND ( message:'failed' OR message:'timeout' )	warm	71.49	71.26	-0.32%	25.23	24.94	-1.14%	65.00	65.00	0.00%	124.00	121.00	-2.42%	173.50	171.00	-1.44%	3459.00	3466.00	+0.20%

Have a great time!

[dkharms]

@seqbenchbot up main bulk

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

Your request was successfully served.
Identificator for your ongoing benchmark - 3a13f7af.

Here is a list of helpful links:

• Take a look at Grafana dashboard;
• Live-tailing logs are also available;

Have a great time!

[dkharms]

@seqbenchbot down 3a13f7af

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

The benchmark with identificator 3a13f7af was finished.
I've prepared a summary for you. Click on Show summary button to see it:

Show summary

Query	Type	mean (ms)			stddev (ms)			p(50) (ms)			p(95) (ms)			p(99) (ms)			iterations
		base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff
bulk	warm	70.93	70.93	-0.00%	26.40	27.66	+4.80%	64.00	63.00	-1.56%	124.50	127.00	+2.01%	165.00	170.00	+3.03%	13088.00	13154.00	+0.50%

Have a great time!

[dkharms]

@seqbenchbot up main bulk

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

Your request was successfully served.
Identificator for your ongoing benchmark - 29e733d8.

Here is a list of helpful links:

• Take a look at Grafana dashboard;
• Live-tailing logs are also available;

Have a great time!

[dkharms]

@seqbenchbot down 29e733d8

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

The benchmark with identificator 29e733d8 was finished.
I've prepared a summary for you. Click on Show summary button to see it:

Show summary

Query	Type	mean (ms)			stddev (ms)			p(50) (ms)			p(95) (ms)			p(99) (ms)			iterations
		base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff
bulk	warm	69.95	69.78	-0.25%	26.18	26.57	+1.50%	63.00	63.00	0.00%	122.00	123.00	+0.82%	162.00	166.00	+2.47%	13679.00	13623.00	-0.41%

Have a great time!

[dkharms]

@seqbenchbot up main bulk

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

Your request was successfully served.
Identificator for your ongoing benchmark - b1727103.

Here is a list of helpful links:

• Take a look at Grafana dashboard;
• Live-tailing logs are also available;

Have a great time!

[dkharms]

@seqbenchbot down b1727103

[seqbenchbot]

Nice, @dkharms <(-^,^-)=b!

The benchmark with identificator b1727103 was finished.
I've prepared a summary for you. Click on Show summary button to see it:

Show summary

Query	Type	mean (ms)			stddev (ms)			p(50) (ms)			p(95) (ms)			p(99) (ms)			iterations
		base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff	base	comp	diff
bulk	warm	72.81	72.37	-0.60%	29.14	28.83	-1.06%	65.00	64.00	-1.54%	132.00	130.00	-1.52%	175.00	179.00	+2.29%	40040.00	39925.00	-0.29%

Have a great time!

[github-actions]

🔴 Performance Degradation

Some benchmarks have degraded compared to the previous run.
Click on Show table button to see full list of degraded benchmarks.

Show table

Name	Previous	Current	Ratio	Verdict
MutexListAppend-4	5115f7	674dbc
	196.07 MB/s	168.78 MB/s	0.86	🔴
	83287562.00 ns/op	94799666.00 ns/op	1.14	🔴