Fix: FLEXMEASURES_*_TTL config handling: support ISO-8601, int days, and proper defaults

[BelhsanHmida]

Description

Currently, FLEXMEASURES_JOB_TTL and FLEXMEASURES_PLANNING_TTL have several issues:

1. Type conflicts with defaults

   • Existing docs and code use timedelta(days=1) / timedelta(days=7) as defaults.
   • If a user sets an ISO-8601 string (e.g., "P2D") or an integer in the config, passing a timedelta as the .get() default causes a runtime error when calling .total_seconds().

2. Unclear “persist forever” behavior

   • Previously, None and negative TTLs were not consistently handled.
   • Defaults could accidentally result in “persist forever” instead of TTLs defaults set in flexmeasures docs.

3. Limited input formats

   • Only timedelta was accepted.
   • Intuitive formats like 2 (days) or ISO-8601 strings were unsupported.

• Fix FLEXMEASURES_JOB_TTL and FLEXMEASURES_PLANNING_TTL configuration handling.
• Introduced normalize_ttl(value, default_days) helper to convert config values to timedelta internally.
• Supported input formats:
  • ISO-8601 duration strings (recommended), e.g., "P1D" / "P7D"
  • Integers → number of days
  • Integer -1 → persist forever
  • None → use sensible default (1 day for job TTL, 7 days for planning TTL)
• Updated Job.create calls to use normalized TTLs safely.
• Updated configuration documentation to add supported types while preserving original defaults.
• Added changelog entry in documentation/changelog.rst.

How to test

• Set FLEXMEASURES_JOB_TTL and FLEXMEASURES_PLANNING_TTL in flexmeasures.cfg with:
  • ISO-8601 strings, e.g., "P2D" or "PT12H"
  • Integers, e.g., 2
  • -1 for persist forever
• Run scheduling and forecasting jobs, check that ttl and result_ttl are correctly applied.
• Verify defaults are applied correctly when no value is set in config.

Sign-off

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on code under GPL or other license that is incompatible with FlexMeasures

[read-the-docs-community]

Documentation build overview

📚 flexmeasures | 🛠️ Build #30782189 | 📁 Comparing e720f7b against latest (75e05d4)

🔍 Preview build

Show files changed (5 files in total): 📝 5 modified | ➕ 0 added | ➖ 0 deleted

File	Status
changelog.html	📝 modified
configuration.html	📝 modified
genindex.html	📝 modified
_autosummary/flexmeasures.utils.time_utils.html	📝 modified
api/v3_0.html	📝 modified

[Flix6x]

I'm not sure issue 2 is correct. Did you see the default TTLs were coming from utils.config_defaults? Or what was the actual case that was inconsistently handled?